Add support for tiled images and the UDIM naming scheme

This patch contains the work that I did during my week at the Code Quest - adding support for tiled images to Blender.

With this patch, images now contain a list of tiles. By default, this just contains one tile, but if the source type is set to Tiled, the user can add additional tiles. When acquiring an ImBuf, the tile to be loaded is specified in the ImageUser.
Therefore, code that is not yet aware of tiles will just access the default tile as usual.

The filenames of the additional tiles are derived from the original filename according to the UDIM naming scheme - the filename contains an index that is calculated as (1001 + 10*<y coordinate of the tile> + <x coordinate of the tile>), where the x coordinate never goes above 9.
Internally, the various tiles are stored in a cache just like sequences. When acquired for the first time, the code will try to load the corresponding file from disk. Alternatively, a new operator can be used to initialize the tile similar to the New Image operator.

The following features are supported so far:
- Automatic detection and loading of all tiles when opening the first tile (1001)
- Saving all tiles
- Adding and removing tiles
- Filling tiles with generated images
- Drawing all tiles in the Image Editor
- Viewing a tiled grid even if no image is selected
- Rendering tiled images in Eevee
- Rendering tiled images in Cycles (in SVM mode)
- Automatically skipping loading of unused tiles in Cycles
- 2D texture painting (also across tiles)
- 3D texture painting (also across tiles, only limitation: individual faces can not cross tile borders)
- Assigning custom labels to individual tiles (drawn in the Image Editor instead of the ID)
- Different resolutions between tiles

There still are some missing features that will be added later (see T72390):
- Workbench engine support
- Packing/Unpacking support
- Baking support
- Cycles OSL support
- many other Blender features that rely on images

Thanks to Brecht for the review and to all who tested the intermediate versions!

Differential Revision: https://developer.blender.org/D3509

18 files changed, 1244 insertions, 405 deletions

diff --git a/source/blender/editors/include/ED_image.h b/source/blender/editors/include/ED_image.h
index 69742af9f50..e6d8684a8b2 100644
--- a/source/blender/editors/include/ED_image.h
+++ b/source/blender/editors/include/ED_image.h
@@ -50,7 +50,7 @@ bool ED_space_image_color_sample(struct SpaceImage *sima,
                                  struct ARegion *ar,
                                  int mval[2],
                                  float r_col[3]);
-struct ImBuf *ED_space_image_acquire_buffer(struct SpaceImage *sima, void **r_lock);
+struct ImBuf *ED_space_image_acquire_buffer(struct SpaceImage *sima, void **r_lock, int tile);
 void ED_space_image_release_buffer(struct SpaceImage *sima, struct ImBuf *ibuf, void *lock);
 bool ED_space_image_has_buffer(struct SpaceImage *sima);
 
diff --git a/source/blender/editors/include/ED_paint.h b/source/blender/editors/include/ED_paint.h
index fec4beea809..e15e4c45c4a 100644
--- a/source/blender/editors/include/ED_paint.h
+++ b/source/blender/editors/include/ED_paint.h
@@ -36,15 +36,25 @@ void ED_keymap_paint(struct wmKeyConfig *keyconf);
 
 /* paint_image.c */
 void ED_imapaint_clear_partial_redraw(void);
-void ED_imapaint_dirty_region(
-    struct Image *ima, struct ImBuf *ibuf, int x, int y, int w, int h, bool find_old);
-void ED_imapaint_bucket_fill(struct bContext *C, float color[3], struct wmOperator *op);
+void ED_imapaint_dirty_region(struct Image *ima,
+                              struct ImBuf *ibuf,
+                              int tile_number,
+                              int x,
+                              int y,
+                              int w,
+                              int h,
+                              bool find_old);
+void ED_imapaint_bucket_fill(struct bContext *C,
+                             float color[3],
+                             struct wmOperator *op,
+                             const int mouse[2]);
 
 /* image_undo.c */
 void ED_image_undo_push_begin(const char *name, int paint_mode);
 void ED_image_undo_push_begin_with_image(const char *name,
                                          struct Image *image,
-                                         struct ImBuf *ibuf);
+                                         struct ImBuf *ibuf,
+                                         int tile_number);
 
 void ED_image_undo_push_end(void);
 void ED_image_undo_restore(struct UndoStep *us);
@@ -54,6 +64,7 @@ void ED_image_undosys_type(struct UndoType *ut);
 void *ED_image_paint_tile_find(struct ListBase *undo_tiles,
                                struct Image *ima,
                                struct ImBuf *ibuf,
+                               int tile_number,
                                int x_tile,
                                int y_tile,
                                unsigned short **r_mask,
@@ -62,6 +73,7 @@ void *ED_image_paint_tile_push(struct ListBase *undo_tiles,
                                struct Image *ima,
                                struct ImBuf *ibuf,
                                struct ImBuf **tmpibuf,
+                               int tile_number,
                                int x_tile,
                                int y_tile,
                                unsigned short **r_mask,
diff --git a/source/blender/editors/include/ED_screen.h b/source/blender/editors/include/ED_screen.h
index 4ca7c8f96ad..6a801fc9928 100644
--- a/source/blender/editors/include/ED_screen.h
+++ b/source/blender/editors/include/ED_screen.h
@@ -120,7 +120,7 @@ void ED_region_info_draw_multiline(ARegion *ar,
 void ED_region_image_metadata_draw(
     int x, int y, struct ImBuf *ibuf, const rctf *frame, float zoomx, float zoomy);
 void ED_region_image_metadata_panel_draw(struct ImBuf *ibuf, struct uiLayout *layout);
-void ED_region_grid_draw(struct ARegion *ar, float zoomx, float zoomy);
+void ED_region_grid_draw(struct ARegion *ar, float zoomx, float zoomy, float x0, float y0);
 float ED_region_blend_alpha(struct ARegion *ar);
 void ED_region_visible_rect_calc(struct ARegion *ar, struct rcti *rect);
 const rcti *ED_region_visible_rect(ARegion *ar);
diff --git a/source/blender/editors/interface/interface_ops.c b/source/blender/editors/interface/interface_ops.c
index 2a9ebdfaea9..cc677f8f7cb 100644
--- a/source/blender/editors/interface/interface_ops.c
+++ b/source/blender/editors/interface/interface_ops.c
@@ -1708,7 +1708,7 @@ void UI_drop_color_copy(wmDrag *drag, wmDropBox *drop)
   RNA_boolean_set(drop->ptr, "gamma", drag_info->gamma_corrected);
 }
 
-static int drop_color_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(event))
+static int drop_color_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
   ARegion *ar = CTX_wm_region(C);
   uiBut *but = NULL;
@@ -1751,7 +1751,7 @@ static int drop_color_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(
       srgb_to_linearrgb_v3_v3(color, color);
     }
 
-    ED_imapaint_bucket_fill(C, color, op);
+    ED_imapaint_bucket_fill(C, color, op, event->mval);
   }
 
   ED_region_tag_redraw(ar);
diff --git a/source/blender/editors/object/object_bake_api.c b/source/blender/editors/object/object_bake_api.c
index 9e9cfe1beed..acecbc47c28 100644
--- a/source/blender/editors/object/object_bake_api.c
+++ b/source/blender/editors/object/object_bake_api.c
@@ -305,9 +305,12 @@ static void refresh_images(BakeImages *bake_images)
   int i;
   for (i = 0; i < bake_images->size; i++) {
     Image *ima = bake_images->data[i].image;
-    if (ima->ok == IMA_OK_LOADED) {
-      GPU_free_image(ima);
-      DEG_id_tag_update(&ima->id, 0);
+    LISTBASE_FOREACH (ImageTile *, tile, &ima->tiles) {
+      if (tile->ok == IMA_OK_LOADED) {
+        GPU_free_image(ima);
+        DEG_id_tag_update(&ima->id, 0);
+        break;
+      }
     }
   }
 }
diff --git a/source/blender/editors/render/render_preview.c b/source/blender/editors/render/render_preview.c
index 1fe299e58a9..0ed37bbc5af 100644
--- a/source/blender/editors/render/render_preview.c
+++ b/source/blender/editors/render/render_preview.c
@@ -1118,10 +1118,16 @@ static void icon_preview_startjob(void *customdata, short *stop, short *do_updat
     if (idtype == ID_IM) {
       Image *ima = (Image *)id;
       ImBuf *ibuf = NULL;
-      ImageUser iuser = {NULL};
+      ImageUser iuser;
+      BKE_imageuser_default(&iuser);
 
-      /* ima->ok is zero when Image cannot load */
-      if (ima == NULL || ima->ok == 0) {
+      if (ima == NULL) {
+        return;
+      }
+
+      ImageTile *tile = BKE_image_get_tile(ima, 0);
+      /* tile->ok is zero when Image cannot load */
+      if (tile->ok == 0) {
         return;
       }
 
diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 36a2b4c2893..e3070903ccc 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -3212,15 +3212,15 @@ void ED_region_image_metadata_panel_draw(ImBuf *ibuf, uiLayout *layout)
   IMB_metadata_foreach(ibuf, metadata_panel_draw_field, &ctx);
 }
 
-void ED_region_grid_draw(ARegion *ar, float zoomx, float zoomy)
+void ED_region_grid_draw(ARegion *ar, float zoomx, float zoomy, float x0, float y0)
 {
   float gridsize, gridstep = 1.0f / 32.0f;
   float fac, blendfac;
   int x1, y1, x2, y2;
 
-  /* the image is located inside (0, 0), (1, 1) as set by view2d */
-  UI_view2d_view_to_region(&ar->v2d, 0.0f, 0.0f, &x1, &y1);
-  UI_view2d_view_to_region(&ar->v2d, 1.0f, 1.0f, &x2, &y2);
+  /* the image is located inside (x0, y0), (x0+1, y0+1) as set by view2d */
+  UI_view2d_view_to_region(&ar->v2d, x0, y0, &x1, &y1);
+  UI_view2d_view_to_region(&ar->v2d, x0 + 1.0f, y0 + 1.0f, &x2, &y2);
 
   GPUVertFormat *format = immVertexFormat();
   uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
diff --git a/source/blender/editors/sculpt_paint/paint_image.c b/source/blender/editors/sculpt_paint/paint_image.c
index 0b770f17314..de09a52258f 100644
--- a/source/blender/editors/sculpt_paint/paint_image.c
+++ b/source/blender/editors/sculpt_paint/paint_image.c
@@ -119,7 +119,8 @@ void imapaint_region_tiles(
   *ty = (y >> ED_IMAGE_UNDO_TILE_BITS);
 }
 
-void ED_imapaint_dirty_region(Image *ima, ImBuf *ibuf, int x, int y, int w, int h, bool find_old)
+void ED_imapaint_dirty_region(
+    Image *ima, ImBuf *ibuf, int tile_number, int x, int y, int w, int h, bool find_old)
 {
   ImBuf *tmpibuf = NULL;
   int tilex, tiley, tilew, tileh, tx, ty;
@@ -152,7 +153,7 @@ void ED_imapaint_dirty_region(Image *ima, ImBuf *ibuf, int x, int y, int w, int
   for (ty = tiley; ty <= tileh; ty++) {
     for (tx = tilex; tx <= tilew; tx++) {
       ED_image_paint_tile_push(
-          undo_tiles, ima, ibuf, &tmpibuf, tx, ty, NULL, NULL, false, find_old);
+          undo_tiles, ima, ibuf, &tmpibuf, tile_number, tx, ty, NULL, NULL, false, find_old);
     }
   }
 
@@ -163,7 +164,8 @@ void ED_imapaint_dirty_region(Image *ima, ImBuf *ibuf, int x, int y, int w, int
   }
 }
 
-void imapaint_image_update(SpaceImage *sima, Image *image, ImBuf *ibuf, short texpaint)
+void imapaint_image_update(
+    SpaceImage *sima, Image *image, ImBuf *ibuf, ImageUser *iuser, short texpaint)
 {
   if (imapaintpartial.x1 != imapaintpartial.x2 && imapaintpartial.y1 != imapaintpartial.y2) {
     IMB_partial_display_buffer_update_delayed(
@@ -180,8 +182,7 @@ void imapaint_image_update(SpaceImage *sima, Image *image, ImBuf *ibuf, short te
     int h = imapaintpartial.y2 - imapaintpartial.y1;
     if (w && h) {
       /* Testing with partial update in uv editor too */
-      GPU_paint_update_image(
-          image, (sima ? &sima->iuser : NULL), imapaintpartial.x1, imapaintpartial.y1, w, h);
+      GPU_paint_update_image(image, iuser, imapaintpartial.x1, imapaintpartial.y1, w, h);
     }
   }
 }
@@ -623,7 +624,7 @@ static void paint_stroke_done(const bContext *C, struct PaintStroke *stroke)
         else {
           srgb_to_linearrgb_v3_v3(color, BKE_brush_color_get(scene, brush));
         }
-        paint_2d_bucket_fill(C, color, brush, pop->prevmouse, pop->custom_paint);
+        paint_2d_bucket_fill(C, color, brush, pop->startmouse, pop->prevmouse, pop->custom_paint);
       }
       else {
         paint_proj_stroke(C,
@@ -1297,7 +1298,10 @@ void PAINT_OT_brush_colors_flip(wmOperatorType *ot)
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-void ED_imapaint_bucket_fill(struct bContext *C, float color[3], wmOperator *op)
+void ED_imapaint_bucket_fill(struct bContext *C,
+                             float color[3],
+                             wmOperator *op,
+                             const int mouse[2])
 {
   wmWindowManager *wm = CTX_wm_manager(C);
   SpaceImage *sima = CTX_wm_space_image(C);
@@ -1307,7 +1311,8 @@ void ED_imapaint_bucket_fill(struct bContext *C, float color[3], wmOperator *op)
 
   ED_image_undo_push_begin(op->type->name, PAINT_MODE_TEXTURE_2D);
 
-  paint_2d_bucket_fill(C, color, NULL, NULL, NULL);
+  float mouse_init[2] = {mouse[0], mouse[1]};
+  paint_2d_bucket_fill(C, color, NULL, mouse_init, NULL, NULL);
 
   BKE_undosys_step_push(wm->undo_stack, C, op->type->name);
 
diff --git a/source/blender/editors/sculpt_paint/paint_image_2d.c b/source/blender/editors/sculpt_paint/paint_image_2d.c
index 004caae8a00..06d79b8a49d 100644
--- a/source/blender/editors/sculpt_paint/paint_image_2d.c
+++ b/source/blender/editors/sculpt_paint/paint_image_2d.c
@@ -30,6 +30,7 @@
 #include "DNA_space_types.h"
 #include "DNA_object_types.h"
 
+#include "BLI_listbase.h"
 #include "BLI_math_color_blend.h"
 #include "BLI_stack.h"
 #include "BLI_bitmap.h"
@@ -84,22 +85,21 @@ typedef struct BrushPainterCache {
   unsigned short *tex_mask_old;
   unsigned int tex_mask_old_w;
   unsigned int tex_mask_old_h;
+
+  int image_size[2];
 } BrushPainterCache;
 
 typedef struct BrushPainter {
   Scene *scene;
   Brush *brush;
 
-  float lastpaintpos[2];  /* position of last paint op */
-  float startpaintpos[2]; /* position of first paint */
-
   short firsttouch; /* first paint op */
 
   struct ImagePool *pool; /* image pool */
   rctf tex_mapping;       /* texture coordinate mapping */
   rctf mask_mapping;      /* mask texture coordinate mapping */
 
-  BrushPainterCache cache;
+  bool cache_invert;
 } BrushPainter;
 
 typedef struct ImagePaintRegion {
@@ -108,6 +108,27 @@ typedef struct ImagePaintRegion {
   int width, height;
 } ImagePaintRegion;
 
+typedef enum ImagePaintTileState {
+  PAINT2D_TILE_UNINITIALIZED = 0,
+  PAINT2D_TILE_MISSING,
+  PAINT2D_TILE_READY,
+} ImagePaintTileState;
+
+typedef struct ImagePaintTile {
+  ImageUser iuser;
+  ImBuf *canvas;
+  float radius_fac;
+  int size[2];
+  float uv_origin[2]; /* Stores the position of this tile in UV space. */
+  bool need_redraw;
+  BrushPainterCache cache;
+
+  ImagePaintTileState state;
+
+  float last_paintpos[2];  /* position of last paint op */
+  float start_paintpos[2]; /* position of first paint */
+} ImagePaintTile;
+
 typedef struct ImagePaintState {
   BrushPainter *painter;
   SpaceImage *sima;
@@ -119,10 +140,7 @@ typedef struct ImagePaintState {
   Brush *brush;
   short tool, blend;
   Image *image;
-  ImBuf *canvas;
   ImBuf *clonecanvas;
-  const char *warnpackedfile;
-  const char *warnmultifile;
 
   bool do_masking;
 
@@ -133,7 +151,8 @@ typedef struct ImagePaintState {
   int do_facesel;
   int symmetry;
 
-  bool need_redraw;
+  ImagePaintTile *tiles;
+  int num_tiles;
 
   BlurKernel *blurkernel;
 } ImagePaintState;
@@ -145,63 +164,60 @@ static BrushPainter *brush_painter_2d_new(Scene *scene, Brush *brush, bool inver
   painter->brush = brush;
   painter->scene = scene;
   painter->firsttouch = 1;
-  painter->cache.lastdiameter = -1; /* force ibuf create in refresh */
-  painter->cache.invert = invert;
+  painter->cache_invert = invert;
 
   return painter;
 }
 
-static void brush_painter_2d_require_imbuf(BrushPainter *painter,
-                                           bool use_float,
-                                           bool use_color_correction)
+static void brush_painter_2d_require_imbuf(
+    Brush *brush, ImagePaintTile *tile, bool use_float, bool use_color_correction, bool invert)
 {
-  Brush *brush = painter->brush;
+  BrushPainterCache *cache = &tile->cache;
 
-  if ((painter->cache.use_float != use_float)) {
-    if (painter->cache.ibuf) {
-      IMB_freeImBuf(painter->cache.ibuf);
+  if ((cache->use_float != use_float)) {
+    if (cache->ibuf) {
+      IMB_freeImBuf(cache->ibuf);
     }
-    if (painter->cache.curve_mask) {
-      MEM_freeN(painter->cache.curve_mask);
+    if (cache->curve_mask) {
+      MEM_freeN(cache->curve_mask);
     }
-    if (painter->cache.tex_mask) {
-      MEM_freeN(painter->cache.tex_mask);
+    if (cache->tex_mask) {
+      MEM_freeN(cache->tex_mask);
     }
-    if (painter->cache.tex_mask_old) {
-      MEM_freeN(painter->cache.tex_mask_old);
+    if (cache->tex_mask_old) {
+      MEM_freeN(cache->tex_mask_old);
     }
-    painter->cache.ibuf = NULL;
-    painter->cache.curve_mask = NULL;
-    painter->cache.tex_mask = NULL;
-    painter->cache.lastdiameter = -1; /* force ibuf create in refresh */
-  }
-
-  painter->cache.use_float = use_float;
-  painter->cache.use_color_correction = use_float && use_color_correction;
-  painter->cache.is_texbrush = (brush->mtex.tex && brush->imagepaint_tool == PAINT_TOOL_DRAW) ?
-                                   true :
-                                   false;
-  painter->cache.is_maskbrush = (brush->mask_mtex.tex) ? true : false;
+    cache->ibuf = NULL;
+    cache->curve_mask = NULL;
+    cache->tex_mask = NULL;
+    cache->lastdiameter = -1; /* force ibuf create in refresh */
+    cache->invert = invert;
+  }
+
+  cache->use_float = use_float;
+  cache->use_color_correction = use_float && use_color_correction;
+  cache->is_texbrush = (brush->mtex.tex && brush->imagepaint_tool == PAINT_TOOL_DRAW) ? true :
+                                                                                        false;
+  cache->is_maskbrush = (brush->mask_mtex.tex) ? true : false;
 }
 
-static void brush_painter_2d_free(BrushPainter *painter)
+static void brush_painter_cache_2d_free(BrushPainterCache *cache)
 {
-  if (painter->cache.ibuf) {
-    IMB_freeImBuf(painter->cache.ibuf);
+  if (cache->ibuf) {
+    IMB_freeImBuf(cache->ibuf);
   }
-  if (painter->cache.texibuf) {
-    IMB_freeImBuf(painter->cache.texibuf);
+  if (cache->texibuf) {
+    IMB_freeImBuf(cache->texibuf);
   }
-  if (painter->cache.curve_mask) {
-    MEM_freeN(painter->cache.curve_mask);
+  if (cache->curve_mask) {
+    MEM_freeN(cache->curve_mask);
   }
-  if (painter->cache.tex_mask) {
-    MEM_freeN(painter->cache.tex_mask);
+  if (cache->tex_mask) {
+    MEM_freeN(cache->tex_mask);
   }
-  if (painter->cache.tex_mask_old) {
-    MEM_freeN(painter->cache.tex_mask_old);
+  if (cache->tex_mask_old) {
+    MEM_freeN(cache->tex_mask_old);
   }
-  MEM_freeN(painter);
 }
 
 static void brush_imbuf_tex_co(rctf *mapping, int x, int y, float texco[3])
@@ -212,7 +228,7 @@ static void brush_imbuf_tex_co(rctf *mapping, int x, int y, float texco[3])
 }
 
 /* create a mask with the mask texture */
-static unsigned short *brush_painter_mask_ibuf_new(BrushPainter *painter, int size)
+static unsigned short *brush_painter_mask_ibuf_new(BrushPainter *painter, const int size)
 {
   Scene *scene = painter->scene;
   Brush *brush = painter->brush;
@@ -240,6 +256,7 @@ static unsigned short *brush_painter_mask_ibuf_new(BrushPainter *painter, int si
 
 /* update rectangular section of the brush image */
 static void brush_painter_mask_imbuf_update(BrushPainter *painter,
+                                            ImagePaintTile *tile,
                                             unsigned short *tex_mask_old,
                                             int origx,
                                             int origy,
@@ -247,10 +264,11 @@ static void brush_painter_mask_imbuf_update(BrushPainter *painter,
                                             int h,
                                             int xt,
                                             int yt,
-                                            int diameter)
+                                            const int diameter)
 {
   Scene *scene = painter->scene;
   Brush *brush = painter->brush;
+  BrushPainterCache *cache = &tile->cache;
   rctf tex_mapping = painter->mask_mapping;
   struct ImagePool *pool = painter->pool;
   unsigned short res;
@@ -259,8 +277,8 @@ static void brush_painter_mask_imbuf_update(BrushPainter *painter,
 
   int x, y, thread = 0;
 
-  unsigned short *tex_mask = painter->cache.tex_mask;
-  unsigned short *tex_mask_cur = painter->cache.tex_mask_old;
+  unsigned short *tex_mask = cache->tex_mask;
+  unsigned short *tex_mask_cur = cache->tex_mask_old;
 
   /* fill pixels */
   for (y = origy; y < h; y++) {
@@ -280,8 +298,7 @@ static void brush_painter_mask_imbuf_update(BrushPainter *painter,
 
       /* read from old texture buffer */
       if (use_texture_old) {
-        res = *(tex_mask_old +
-                ((y - origy + yt) * painter->cache.tex_mask_old_w + (x - origx + xt)));
+        res = *(tex_mask_old + ((y - origy + yt) * cache->tex_mask_old_w + (x - origx + xt)));
       }
 
       /* write to new texture mask */
@@ -298,10 +315,11 @@ static void brush_painter_mask_imbuf_update(BrushPainter *painter,
  * textures that stick to the surface where only part of the pixels are new
  */
 static void brush_painter_mask_imbuf_partial_update(BrushPainter *painter,
+                                                    ImagePaintTile *tile,
                                                     const float pos[2],
-                                                    int diameter)
+                                                    const int diameter)
 {
-  BrushPainterCache *cache = &painter->cache;
+  BrushPainterCache *cache = &tile->cache;
   unsigned short *tex_mask_old;
   int destx, desty, srcx, srcy, w, h, x1, y1, x2, y2;
 
@@ -319,15 +337,16 @@ static void brush_painter_mask_imbuf_partial_update(BrushPainter *painter,
   if (tex_mask_old) {
     ImBuf maskibuf;
     ImBuf maskibuf_old;
-    maskibuf.x = maskibuf.y = diameter;
+    maskibuf.x = diameter;
+    maskibuf.y = diameter;
     maskibuf_old.x = cache->tex_mask_old_w;
     maskibuf_old.y = cache->tex_mask_old_h;
 
     srcx = srcy = 0;
     w = cache->tex_mask_old_w;
     h = cache->tex_mask_old_h;
-    destx = (int)floorf(painter->lastpaintpos[0]) - (int)floorf(pos[0]) + (diameter / 2 - w / 2);
-    desty = (int)floorf(painter->lastpaintpos[1]) - (int)floorf(pos[1]) + (diameter / 2 - h / 2);
+    destx = (int)floorf(tile->last_paintpos[0]) - (int)floorf(pos[0]) + (diameter / 2 - w / 2);
+    desty = (int)floorf(tile->last_paintpos[1]) - (int)floorf(pos[1]) + (diameter / 2 - h / 2);
 
     /* hack, use temporary rects so that clipping works */
     IMB_rectclip(&maskibuf, &maskibuf_old, &destx, &desty, &srcx, &srcy, &w, &h);
@@ -345,7 +364,8 @@ static void brush_painter_mask_imbuf_partial_update(BrushPainter *painter,
 
   /* blend existing texture in new position */
   if ((x1 < x2) && (y1 < y2)) {
-    brush_painter_mask_imbuf_update(painter, tex_mask_old, x1, y1, x2, y2, srcx, srcy, diameter);
+    brush_painter_mask_imbuf_update(
+        painter, tile, tex_mask_old, x1, y1, x2, y2, srcx, srcy, diameter);
   }
 
   if (tex_mask_old) {
@@ -354,16 +374,17 @@ static void brush_painter_mask_imbuf_partial_update(BrushPainter *painter,
 
   /* sample texture in new areas */
   if ((0 < x1) && (0 < diameter)) {
-    brush_painter_mask_imbuf_update(painter, NULL, 0, 0, x1, diameter, 0, 0, diameter);
+    brush_painter_mask_imbuf_update(painter, tile, NULL, 0, 0, x1, diameter, 0, 0, diameter);
   }
   if ((x2 < diameter) && (0 < diameter)) {
-    brush_painter_mask_imbuf_update(painter, NULL, x2, 0, diameter, diameter, 0, 0, diameter);
+    brush_painter_mask_imbuf_update(
+        painter, tile, NULL, x2, 0, diameter, diameter, 0, 0, diameter);
   }
   if ((x1 < x2) && (0 < y1)) {
-    brush_painter_mask_imbuf_update(painter, NULL, x1, 0, x2, y1, 0, 0, diameter);
+    brush_painter_mask_imbuf_update(painter, tile, NULL, x1, 0, x2, y1, 0, 0, diameter);
   }
   if ((x1 < x2) && (y2 < diameter)) {
-    brush_painter_mask_imbuf_update(painter, NULL, x1, y2, x2, diameter, 0, 0, diameter);
+    brush_painter_mask_imbuf_update(painter, tile, NULL, x1, y2, x2, diameter, 0, 0, diameter);
   }
 
   /* through with sampling, now update sizes */
@@ -445,13 +466,12 @@ static unsigned short *brush_painter_curve_mask_new(BrushPainter *painter,
 }
 
 /* create imbuf with brush color */
-static ImBuf *brush_painter_imbuf_new(BrushPainter *painter,
-                                      int size,
-                                      float pressure,
-                                      float distance)
+static ImBuf *brush_painter_imbuf_new(
+    BrushPainter *painter, ImagePaintTile *tile, const int size, float pressure, float distance)
 {
   Scene *scene = painter->scene;
   Brush *brush = painter->brush;
+  BrushPainterCache *cache = &tile->cache;
 
   const char *display_device = scene->display_settings.display_device;
   struct ColorManagedDisplay *display = IMB_colormanagement_display_get_named(display_device);
@@ -459,9 +479,9 @@ static ImBuf *brush_painter_imbuf_new(BrushPainter *painter,
   rctf tex_mapping = painter->tex_mapping;
   struct ImagePool *pool = painter->pool;
 
-  bool use_color_correction = painter->cache.use_color_correction;
-  bool use_float = painter->cache.use_float;
-  bool is_texbrush = painter->cache.is_texbrush;
+  bool use_color_correction = cache->use_color_correction;
+  bool use_float = cache->use_float;
+  bool is_texbrush = cache->is_texbrush;
 
   int x, y, thread = 0;
   float brush_rgb[3];
@@ -471,14 +491,8 @@ static ImBuf *brush_painter_imbuf_new(BrushPainter *painter,
 
   /* get brush color */
   if (brush->imagepaint_tool == PAINT_TOOL_DRAW) {
-    paint_brush_color_get(scene,
-                          brush,
-                          use_color_correction,
-                          painter->cache.invert,
-                          distance,
-                          pressure,
-                          brush_rgb,
-                          display);
+    paint_brush_color_get(
+        scene, brush, use_color_correction, cache->invert, distance, pressure, brush_rgb, display);
   }
   else {
     brush_rgb[0] = 1.0f;
@@ -526,11 +540,19 @@ static ImBuf *brush_painter_imbuf_new(BrushPainter *painter,
 }
 
 /* update rectangular section of the brush image */
-static void brush_painter_imbuf_update(
-    BrushPainter *painter, ImBuf *oldtexibuf, int origx, int origy, int w, int h, int xt, int yt)
+static void brush_painter_imbuf_update(BrushPainter *painter,
+                                       ImagePaintTile *tile,
+                                       ImBuf *oldtexibuf,
+                                       int origx,
+                                       int origy,
+                                       int w,
+                                       int h,
+                                       int xt,
+                                       int yt)
 {
   Scene *scene = painter->scene;
   Brush *brush = painter->brush;
+  BrushPainterCache *cache = &tile->cache;
 
   const char *display_device = scene->display_settings.display_device;
   struct ColorManagedDisplay *display = IMB_colormanagement_display_get_named(display_device);
@@ -538,21 +560,21 @@ static void brush_painter_imbuf_update(
   rctf tex_mapping = painter->tex_mapping;
   struct ImagePool *pool = painter->pool;
 
-  bool use_color_correction = painter->cache.use_color_correction;
-  bool use_float = painter->cache.use_float;
-  bool is_texbrush = painter->cache.is_texbrush;
+  bool use_color_correction = cache->use_color_correction;
+  bool use_float = cache->use_float;
+  bool is_texbrush = cache->is_texbrush;
   bool use_texture_old = (oldtexibuf != NULL);
 
   int x, y, thread = 0;
   float brush_rgb[3];
 
-  ImBuf *ibuf = painter->cache.ibuf;
-  ImBuf *texibuf = painter->cache.texibuf;
+  ImBuf *ibuf = cache->ibuf;
+  ImBuf *texibuf = cache->texibuf;
 
   /* get brush color */
   if (brush->imagepaint_tool == PAINT_TOOL_DRAW) {
     paint_brush_color_get(
-        scene, brush, use_color_correction, painter->cache.invert, 0.0, 1.0, brush_rgb, display);
+        scene, brush, use_color_correction, cache->invert, 0.0, 1.0, brush_rgb, display);
   }
   else {
     brush_rgb[0] = 1.0f;
@@ -641,10 +663,11 @@ static void brush_painter_imbuf_update(
  * can be considerably faster for brushes that change size due to pressure or
  * textures that stick to the surface where only part of the pixels are new */
 static void brush_painter_imbuf_partial_update(BrushPainter *painter,
+                                               ImagePaintTile *tile,
                                                const float pos[2],
-                                               int diameter)
+                                               const int diameter)
 {
-  BrushPainterCache *cache = &painter->cache;
+  BrushPainterCache *cache = &tile->cache;
   ImBuf *oldtexibuf, *ibuf;
   int imbflag, destx, desty, srcx, srcy, w, h, x1, y1, x2, y2;
 
@@ -663,8 +686,8 @@ static void brush_painter_imbuf_partial_update(BrushPainter *painter,
     srcx = srcy = 0;
     w = oldtexibuf->x;
     h = oldtexibuf->y;
-    destx = (int)floorf(painter->lastpaintpos[0]) - (int)floorf(pos[0]) + (diameter / 2 - w / 2);
-    desty = (int)floorf(painter->lastpaintpos[1]) - (int)floorf(pos[1]) + (diameter / 2 - h / 2);
+    destx = (int)floorf(tile->last_paintpos[0]) - (int)floorf(pos[0]) + (diameter / 2 - w / 2);
+    desty = (int)floorf(tile->last_paintpos[1]) - (int)floorf(pos[1]) + (diameter / 2 - h / 2);
 
     IMB_rectclip(cache->texibuf, oldtexibuf, &destx, &desty, &srcx, &srcy, &w, &h);
   }
@@ -681,7 +704,7 @@ static void brush_painter_imbuf_partial_update(BrushPainter *painter,
 
   /* blend existing texture in new position */
   if ((x1 < x2) && (y1 < y2)) {
-    brush_painter_imbuf_update(painter, oldtexibuf, x1, y1, x2, y2, srcx, srcy);
+    brush_painter_imbuf_update(painter, tile, oldtexibuf, x1, y1, x2, y2, srcx, srcy);
   }
 
   if (oldtexibuf) {
@@ -690,29 +713,30 @@ static void brush_painter_imbuf_partial_update(BrushPainter *painter,
 
   /* sample texture in new areas */
   if ((0 < x1) && (0 < ibuf->y)) {
-    brush_painter_imbuf_update(painter, NULL, 0, 0, x1, ibuf->y, 0, 0);
+    brush_painter_imbuf_update(painter, tile, NULL, 0, 0, x1, ibuf->y, 0, 0);
   }
   if ((x2 < ibuf->x) && (0 < ibuf->y)) {
-    brush_painter_imbuf_update(painter, NULL, x2, 0, ibuf->x, ibuf->y, 0, 0);
+    brush_painter_imbuf_update(painter, tile, NULL, x2, 0, ibuf->x, ibuf->y, 0, 0);
   }
   if ((x1 < x2) && (0 < y1)) {
-    brush_painter_imbuf_update(painter, NULL, x1, 0, x2, y1, 0, 0);
+    brush_painter_imbuf_update(painter, tile, NULL, x1, 0, x2, y1, 0, 0);
   }
   if ((x1 < x2) && (y2 < ibuf->y)) {
-    brush_painter_imbuf_update(painter, NULL, x1, y2, x2, ibuf->y, 0, 0);
+    brush_painter_imbuf_update(painter, tile, NULL, x1, y2, x2, ibuf->y, 0, 0);
   }
 }
 
 static void brush_painter_2d_tex_mapping(ImagePaintState *s,
-                                         int diameter,
+                                         ImBuf *canvas,
+                                         const int diameter,
                                          const float startpos[2],
                                          const float pos[2],
                                          const float mouse[2],
                                          int mapmode,
                                          rctf *mapping)
 {
-  float invw = 1.0f / (float)s->canvas->x;
-  float invh = 1.0f / (float)s->canvas->y;
+  float invw = 1.0f / (float)canvas->x;
+  float invh = 1.0f / (float)canvas->y;
   int xmin, ymin, xmax, ymax;
   int ipos[2];
 
@@ -756,6 +780,7 @@ static void brush_painter_2d_tex_mapping(ImagePaintState *s,
 
 static void brush_painter_2d_refresh_cache(ImagePaintState *s,
                                            BrushPainter *painter,
+                                           ImagePaintTile *tile,
                                            const float pos[2],
                                            const float mouse[2],
                                            float pressure,
@@ -765,7 +790,7 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
   const Scene *scene = painter->scene;
   UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
   Brush *brush = painter->brush;
-  BrushPainterCache *cache = &painter->cache;
+  BrushPainterCache *cache = &tile->cache;
   /* Adding 4 pixels of padding for brush antialiasing */
   const int diameter = MAX2(1, size * 2) + 4;
 
@@ -782,7 +807,7 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
   painter->pool = BKE_image_pool_new();
 
   /* determine how can update based on textures used */
-  if (painter->cache.is_texbrush) {
+  if (cache->is_texbrush) {
     if (brush->mtex.brush_map_mode == MTEX_MAP_MODE_VIEW) {
       tex_rotation += ups->brush_rotation;
     }
@@ -794,15 +819,16 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
     }
 
     brush_painter_2d_tex_mapping(s,
+                                 tile->canvas,
                                  diameter,
-                                 painter->startpaintpos,
+                                 tile->start_paintpos,
                                  pos,
                                  mouse,
                                  brush->mtex.brush_map_mode,
                                  &painter->tex_mapping);
   }
 
-  if (painter->cache.is_maskbrush) {
+  if (cache->is_maskbrush) {
     bool renew_maxmask = false;
     bool do_partial_update_mask = false;
     /* invalidate case for all mapping modes */
@@ -822,7 +848,7 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
       renew_maxmask = true;
     }
 
-    if ((diameter != cache->lastdiameter) || (mask_rotation != cache->last_mask_rotation) ||
+    if (diameter != cache->lastdiameter || (mask_rotation != cache->last_mask_rotation) ||
         renew_maxmask) {
       if (cache->tex_mask) {
         MEM_freeN(cache->tex_mask);
@@ -830,15 +856,16 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
       }
 
       brush_painter_2d_tex_mapping(s,
+                                   tile->canvas,
                                    diameter,
-                                   painter->startpaintpos,
+                                   tile->start_paintpos,
                                    pos,
                                    mouse,
                                    brush->mask_mtex.brush_map_mode,
                                    &painter->mask_mapping);
 
       if (do_partial_update_mask) {
-        brush_painter_mask_imbuf_partial_update(painter, pos, diameter);
+        brush_painter_mask_imbuf_partial_update(painter, tile, pos, diameter);
       }
       else {
         cache->tex_mask = brush_painter_mask_ibuf_new(painter, diameter);
@@ -856,8 +883,8 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
   cache->curve_mask = brush_painter_curve_mask_new(painter, diameter, size, pos);
 
   /* detect if we need to recreate image brush buffer */
-  if ((diameter != cache->lastdiameter) || (tex_rotation != cache->last_tex_rotation) ||
-      do_random || update_color) {
+  if (diameter != cache->lastdiameter || (tex_rotation != cache->last_tex_rotation) || do_random ||
+      update_color) {
     if (cache->ibuf) {
       IMB_freeImBuf(cache->ibuf);
       cache->ibuf = NULL;
@@ -865,11 +892,11 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
 
     if (do_partial_update) {
       /* do partial update of texture */
-      brush_painter_imbuf_partial_update(painter, pos, diameter);
+      brush_painter_imbuf_partial_update(painter, tile, pos, diameter);
     }
     else {
       /* create brush from scratch */
-      cache->ibuf = brush_painter_imbuf_new(painter, diameter, pressure, distance);
+      cache->ibuf = brush_painter_imbuf_new(painter, tile, diameter, pressure, distance);
     }
 
     cache->lastdiameter = diameter;
@@ -878,11 +905,11 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
   }
   else if (do_partial_update) {
     /* do only partial update of texture */
-    int dx = (int)floorf(painter->lastpaintpos[0]) - (int)floorf(pos[0]);
-    int dy = (int)floorf(painter->lastpaintpos[1]) - (int)floorf(pos[1]);
+    int dx = (int)floorf(tile->last_paintpos[0]) - (int)floorf(pos[0]);
+    int dy = (int)floorf(tile->last_paintpos[1]) - (int)floorf(pos[1]);
 
     if ((dx != 0) || (dy != 0)) {
-      brush_painter_imbuf_partial_update(painter, pos, diameter);
+      brush_painter_imbuf_partial_update(painter, tile, pos, diameter);
     }
   }
 
@@ -890,6 +917,56 @@ static void brush_painter_2d_refresh_cache(ImagePaintState *s,
   painter->pool = NULL;
 }
 
+static bool paint_2d_ensure_tile_canvas(ImagePaintState *s, int i)
+{
+  if (i == 0) {
+    return true;
+  }
+  if (i >= s->num_tiles) {
+    return false;
+  }
+
+  if (s->tiles[i].state == PAINT2D_TILE_READY) {
+    return true;
+  }
+  if (s->tiles[i].state == PAINT2D_TILE_MISSING) {
+    return false;
+  }
+
+  s->tiles[i].cache.lastdiameter = -1;
+
+  s->tiles[i].iuser.ok = true;
+
+  ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, &s->tiles[i].iuser, NULL);
+  if (ibuf != NULL) {
+    if (ibuf->channels != 4) {
+      s->tiles[i].state = PAINT2D_TILE_MISSING;
+    }
+    else if ((s->tiles[0].canvas->rect && !ibuf->rect) ||
+             (s->tiles[0].canvas->rect_float && !ibuf->rect_float)) {
+      s->tiles[i].state = PAINT2D_TILE_MISSING;
+    }
+    else {
+      s->tiles[i].size[0] = ibuf->x;
+      s->tiles[i].size[1] = ibuf->y;
+      s->tiles[i].radius_fac = sqrtf(((float)ibuf->x * (float)ibuf->y) /
+                                     (s->tiles[0].size[0] * s->tiles[0].size[1]));
+      s->tiles[i].state = PAINT2D_TILE_READY;
+    }
+  }
+  else {
+    s->tiles[i].state = PAINT2D_TILE_MISSING;
+  }
+
+  if (s->tiles[i].state == PAINT2D_TILE_MISSING) {
+    BKE_image_release_ibuf(s->image, ibuf, NULL);
+    return false;
+  }
+
+  s->tiles[i].canvas = ibuf;
+  return true;
+}
+
 /* keep these functions in sync */
 static void paint_2d_ibuf_rgb_get(ImBuf *ibuf, int x, int y, float r_rgb[4])
 {
@@ -935,15 +1012,15 @@ static void paint_2d_ibuf_rgb_set(
   }
 }
 
-static void paint_2d_ibuf_tile_convert(ImBuf *ibuf, int *x, int *y, short tile)
+static void paint_2d_ibuf_tile_convert(ImBuf *ibuf, int *x, int *y, short paint_tile)
 {
-  if (tile & PAINT_TILE_X) {
+  if (paint_tile & PAINT_TILE_X) {
     *x %= ibuf->x;
     if (*x < 0) {
       *x += ibuf->x;
     }
   }
-  if (tile & PAINT_TILE_Y) {
+  if (paint_tile & PAINT_TILE_Y) {
     *y %= ibuf->y;
     if (*y < 0) {
       *y += ibuf->y;
@@ -951,12 +1028,13 @@ static void paint_2d_ibuf_tile_convert(ImBuf *ibuf, int *x, int *y, short tile)
   }
 }
 
-static float paint_2d_ibuf_add_if(ImBuf *ibuf, int x, int y, float *outrgb, short tile, float w)
+static float paint_2d_ibuf_add_if(
+    ImBuf *ibuf, int x, int y, float *outrgb, short paint_tile, float w)
 {
   float inrgb[4];
 
-  if (tile) {
-    paint_2d_ibuf_tile_convert(ibuf, &x, &y, tile);
+  if (paint_tile) {
+    paint_2d_ibuf_tile_convert(ibuf, &x, &y, paint_tile);
   }
   /* need to also do clipping here always since tiled coordinates
    * are not always within bounds */
@@ -973,10 +1051,14 @@ static float paint_2d_ibuf_add_if(ImBuf *ibuf, int x, int y, float *outrgb, shor
   return w;
 }
 
-static void paint_2d_lift_soften(
-    ImagePaintState *s, ImBuf *ibuf, ImBuf *ibufb, int *pos, const short tile)
+static void paint_2d_lift_soften(ImagePaintState *s,
+                                 ImagePaintTile *tile,
+                                 ImBuf *ibuf,
+                                 ImBuf *ibufb,
+                                 int *pos,
+                                 const short paint_tile)
 {
-  bool sharpen = (s->painter->cache.invert ^ ((s->brush->flag & BRUSH_DIR_IN) != 0));
+  bool sharpen = (tile->cache.invert ^ ((s->brush->flag & BRUSH_DIR_IN) != 0));
   float threshold = s->brush->sharp_threshold;
   int x, y, xi, yi, xo, yo, xk, yk;
   float count;
@@ -992,7 +1074,7 @@ static void paint_2d_lift_soften(
   in_off[1] = pos[1];
   out_off[0] = out_off[1] = 0;
 
-  if (!tile) {
+  if (!paint_tile) {
     IMB_rectclip(ibuf, ibufb, &in_off[0], &in_off[1], &out_off[0], &out_off[1], &dim[0], &dim[1]);
 
     if ((dim[0] == 0) || (dim[1] == 0)) {
@@ -1010,8 +1092,8 @@ static void paint_2d_lift_soften(
       yi = in_off[1] + y;
 
       count = 0.0;
-      if (tile) {
-        paint_2d_ibuf_tile_convert(ibuf, &xi, &yi, tile);
+      if (paint_tile) {
+        paint_2d_ibuf_tile_convert(ibuf, &xi, &yi, paint_tile);
         if (xi < ibuf->x && xi >= 0 && yi < ibuf->y && yi >= 0) {
           paint_2d_ibuf_rgb_get(ibuf, xi, yi, rgba);
         }
@@ -1031,7 +1113,7 @@ static void paint_2d_lift_soften(
                                         xi + xk - kernel->pixel_len,
                                         yi + yk - kernel->pixel_len,
                                         outrgb,
-                                        tile,
+                                        paint_tile,
                                         kernel->wdata[xk + yk * kernel->side]);
         }
       }
@@ -1085,7 +1167,7 @@ static void paint_2d_set_region(
 static int paint_2d_torus_split_region(ImagePaintRegion region[4],
                                        ImBuf *dbuf,
                                        ImBuf *sbuf,
-                                       short tile)
+                                       short paint_tile)
 {
   int destx = region->destx;
   int desty = region->desty;
@@ -1096,7 +1178,7 @@ static int paint_2d_torus_split_region(ImagePaintRegion region[4],
   int origw, origh, w, h, tot = 0;
 
   /* convert destination and source coordinates to be within image */
-  if (tile & PAINT_TILE_X) {
+  if (paint_tile & PAINT_TILE_X) {
     destx = destx % dbuf->x;
     if (destx < 0) {
       destx += dbuf->x;
@@ -1106,7 +1188,7 @@ static int paint_2d_torus_split_region(ImagePaintRegion region[4],
       srcx += sbuf->x;
     }
   }
-  if (tile & PAINT_TILE_Y) {
+  if (paint_tile & PAINT_TILE_Y) {
     desty = desty % dbuf->y;
     if (desty < 0) {
       desty += dbuf->y;
@@ -1126,15 +1208,15 @@ static int paint_2d_torus_split_region(ImagePaintRegion region[4],
   paint_2d_set_region(&region[tot++], destx, desty, srcx, srcy, w, h);
 
   /* do 3 other rects if needed */
-  if ((tile & PAINT_TILE_X) && w < origw) {
+  if ((paint_tile & PAINT_TILE_X) && w < origw) {
     paint_2d_set_region(
         &region[tot++], (destx + w) % dbuf->x, desty, (srcx + w) % sbuf->x, srcy, origw - w, h);
   }
-  if ((tile & PAINT_TILE_Y) && h < origh) {
+  if ((paint_tile & PAINT_TILE_Y) && h < origh) {
     paint_2d_set_region(
         &region[tot++], destx, (desty + h) % dbuf->y, srcx, (srcy + h) % sbuf->y, w, origh - h);
   }
-  if ((tile & PAINT_TILE_X) && (tile & PAINT_TILE_Y) && (w < origw) && (h < origh)) {
+  if ((paint_tile & PAINT_TILE_X) && (paint_tile & PAINT_TILE_Y) && (w < origw) && (h < origh)) {
     paint_2d_set_region(&region[tot++],
                         (destx + w) % dbuf->x,
                         (desty + h) % dbuf->y,
@@ -1147,13 +1229,13 @@ static int paint_2d_torus_split_region(ImagePaintRegion region[4],
   return tot;
 }
 
-static void paint_2d_lift_smear(ImBuf *ibuf, ImBuf *ibufb, int *pos, short tile)
+static void paint_2d_lift_smear(ImBuf *ibuf, ImBuf *ibufb, int *pos, short paint_tile)
 {
   ImagePaintRegion region[4];
   int a, tot;
 
   paint_2d_set_region(region, 0, 0, pos[0], pos[1], ibufb->x, ibufb->y);
-  tot = paint_2d_torus_split_region(region, ibufb, ibuf, tile);
+  tot = paint_2d_torus_split_region(region, ibufb, ibuf, paint_tile);
 
   for (a = 0; a < tot; a++) {
     IMB_rectblend(ibufb,
@@ -1229,9 +1311,8 @@ static void paint_2d_convert_brushco(ImBuf *ibufb, const float pos[2], int ipos[
 }
 
 static void paint_2d_do_making_brush(ImagePaintState *s,
+                                     ImagePaintTile *tile,
                                      ImagePaintRegion *region,
-                                     unsigned short *curveb,
-                                     unsigned short *texmaskb,
                                      ImBuf *frombuf,
                                      float mask_max,
                                      short blend,
@@ -1252,21 +1333,21 @@ static void paint_2d_do_making_brush(ImagePaintState *s,
       int origx = region->destx - tx * ED_IMAGE_UNDO_TILE_SIZE;
       int origy = region->desty - ty * ED_IMAGE_UNDO_TILE_SIZE;
 
-      if (s->canvas->rect_float) {
+      if (tile->canvas->rect_float) {
         tmpbuf.rect_float = ED_image_paint_tile_find(
-            undo_tiles, s->image, s->canvas, tx, ty, &mask, false);
+            undo_tiles, s->image, tile->canvas, tile->iuser.tile, tx, ty, &mask, false);
       }
       else {
         tmpbuf.rect = ED_image_paint_tile_find(
-            undo_tiles, s->image, s->canvas, tx, ty, &mask, false);
+            undo_tiles, s->image, tile->canvas, tile->iuser.tile, tx, ty, &mask, false);
       }
 
-      IMB_rectblend(s->canvas,
+      IMB_rectblend(tile->canvas,
                     &tmpbuf,
                     frombuf,
                     mask,
-                    curveb,
-                    texmaskb,
+                    tile->cache.curve_mask,
+                    tile->cache.tex_mask,
                     mask_max,
                     region->destx,
                     region->desty,
@@ -1284,9 +1365,8 @@ static void paint_2d_do_making_brush(ImagePaintState *s,
 
 typedef struct Paint2DForeachData {
   ImagePaintState *s;
+  ImagePaintTile *tile;
   ImagePaintRegion *region;
-  unsigned short *curveb;
-  unsigned short *texmaskb;
   ImBuf *frombuf;
   float mask_max;
   short blend;
@@ -1300,9 +1380,8 @@ static void paint_2d_op_foreach_do(void *__restrict data_v,
 {
   Paint2DForeachData *data = (Paint2DForeachData *)data_v;
   paint_2d_do_making_brush(data->s,
+                           data->tile,
                            data->region,
-                           data->curveb,
-                           data->texmaskb,
                            data->frombuf,
                            data->mask_max,
                            data->blend,
@@ -1313,16 +1392,16 @@ static void paint_2d_op_foreach_do(void *__restrict data_v,
 }
 
 static int paint_2d_op(void *state,
-                       ImBuf *ibufb,
-                       unsigned short *curveb,
-                       unsigned short *texmaskb,
+                       ImagePaintTile *tile,
                        const float lastpos[2],
                        const float pos[2])
 {
   ImagePaintState *s = ((ImagePaintState *)state);
   ImBuf *clonebuf = NULL, *frombuf;
+  ImBuf *canvas = tile->canvas;
+  ImBuf *ibufb = tile->cache.ibuf;
   ImagePaintRegion region[4];
-  short tile = s->symmetry & (PAINT_TILE_X | PAINT_TILE_Y);
+  short paint_tile = s->symmetry & (PAINT_TILE_X | PAINT_TILE_Y);
   short blend = s->blend;
   const float *offset = s->brush->clone.offset;
   float liftpos[2];
@@ -1334,7 +1413,7 @@ static int paint_2d_op(void *state,
 
   /* lift from canvas */
   if (s->tool == PAINT_TOOL_SOFTEN) {
-    paint_2d_lift_soften(s, s->canvas, ibufb, bpos, tile);
+    paint_2d_lift_soften(s, tile, canvas, ibufb, bpos, paint_tile);
     blend = IMB_BLEND_INTERPOLATE;
   }
   else if (s->tool == PAINT_TOOL_SMEAR) {
@@ -1343,12 +1422,12 @@ static int paint_2d_op(void *state,
     }
 
     paint_2d_convert_brushco(ibufb, lastpos, blastpos);
-    paint_2d_lift_smear(s->canvas, ibufb, blastpos, tile);
+    paint_2d_lift_smear(canvas, ibufb, blastpos, paint_tile);
     blend = IMB_BLEND_INTERPOLATE;
   }
   else if (s->tool == PAINT_TOOL_CLONE && s->clonecanvas) {
-    liftpos[0] = pos[0] - offset[0] * s->canvas->x;
-    liftpos[1] = pos[1] - offset[1] * s->canvas->y;
+    liftpos[0] = pos[0] - offset[0] * canvas->x;
+    liftpos[1] = pos[1] - offset[1] * canvas->y;
 
     paint_2d_convert_brushco(ibufb, liftpos, bliftpos);
     clonebuf = paint_2d_lift_clone(s->clonecanvas, ibufb, bliftpos);
@@ -1356,9 +1435,9 @@ static int paint_2d_op(void *state,
 
   frombuf = (clonebuf) ? clonebuf : ibufb;
 
-  if (tile) {
+  if (paint_tile) {
     paint_2d_set_region(region, bpos[0], bpos[1], 0, 0, frombuf->x, frombuf->y);
-    tot = paint_2d_torus_split_region(region, s->canvas, frombuf, tile);
+    tot = paint_2d_torus_split_region(region, canvas, frombuf, paint_tile);
   }
   else {
     paint_2d_set_region(region, bpos[0], bpos[1], 0, 0, frombuf->x, frombuf->y);
@@ -1368,7 +1447,8 @@ static int paint_2d_op(void *state,
   /* blend into canvas */
   for (a = 0; a < tot; a++) {
     ED_imapaint_dirty_region(s->image,
-                             s->canvas,
+                             canvas,
+                             tile->iuser.tile,
                              region[a].destx,
                              region[a].desty,
                              region[a].width,
@@ -1379,7 +1459,7 @@ static int paint_2d_op(void *state,
       /* masking, find original pixels tiles from undo buffer to composite over */
       int tilex, tiley, tilew, tileh;
 
-      imapaint_region_tiles(s->canvas,
+      imapaint_region_tiles(canvas,
                             region[a].destx,
                             region[a].desty,
                             region[a].width,
@@ -1391,14 +1471,13 @@ static int paint_2d_op(void *state,
 
       if (tiley == tileh) {
         paint_2d_do_making_brush(
-            s, &region[a], curveb, texmaskb, frombuf, mask_max, blend, tilex, tiley, tilew, tileh);
+            s, tile, &region[a], frombuf, mask_max, blend, tilex, tiley, tilew, tileh);
       }
       else {
         Paint2DForeachData data;
         data.s = s;
+        data.tile = tile;
         data.region = &region[a];
-        data.curveb = curveb;
-        data.texmaskb = texmaskb;
         data.frombuf = frombuf;
         data.mask_max = mask_max;
         data.blend = blend;
@@ -1412,12 +1491,12 @@ static int paint_2d_op(void *state,
     }
     else {
       /* no masking, composite brush directly onto canvas */
-      IMB_rectblend_threaded(s->canvas,
-                             s->canvas,
+      IMB_rectblend_threaded(canvas,
+                             canvas,
                              frombuf,
                              NULL,
-                             curveb,
-                             texmaskb,
+                             tile->cache.curve_mask,
+                             tile->cache.tex_mask,
                              mask_max,
                              region[a].destx,
                              region[a].desty,
@@ -1439,47 +1518,25 @@ static int paint_2d_op(void *state,
   return 1;
 }
 
-static int paint_2d_canvas_set(ImagePaintState *s, Image *ima)
+static int paint_2d_canvas_set(ImagePaintState *s)
 {
-  ImBuf *ibuf = BKE_image_acquire_ibuf(ima, s->sima ? &s->sima->iuser : NULL, NULL);
-
-  /* verify that we can paint and set canvas */
-  if (ima == NULL) {
-    return 0;
-  }
-  else if (BKE_image_has_packedfile(ima) && ima->rr) {
-    s->warnpackedfile = ima->id.name + 2;
-    return 0;
-  }
-  else if (ibuf && ibuf->channels != 4) {
-    s->warnmultifile = ima->id.name + 2;
-    return 0;
-  }
-  else if (!ibuf || !(ibuf->rect || ibuf->rect_float)) {
-    return 0;
-  }
-
-  s->image = ima;
-  s->canvas = ibuf;
-
   /* set clone canvas */
   if (s->tool == PAINT_TOOL_CLONE) {
-    ima = s->brush->clone.image;
-    ibuf = BKE_image_acquire_ibuf(ima, s->sima ? &s->sima->iuser : NULL, NULL);
+    Image *ima = s->brush->clone.image;
+    ImBuf *ibuf = BKE_image_acquire_ibuf(ima, NULL, NULL);
 
     if (!ima || !ibuf || !(ibuf->rect || ibuf->rect_float)) {
       BKE_image_release_ibuf(ima, ibuf, NULL);
-      BKE_image_release_ibuf(s->image, s->canvas, NULL);
       return 0;
     }
 
     s->clonecanvas = ibuf;
 
     /* temporarily add float rect for cloning */
-    if (s->canvas->rect_float && !s->clonecanvas->rect_float) {
+    if (s->tiles[0].canvas->rect_float && !s->clonecanvas->rect_float) {
       IMB_float_from_rect(s->clonecanvas);
     }
-    else if (!s->canvas->rect_float && !s->clonecanvas->rect) {
+    else if (!s->tiles[0].canvas->rect_float && !s->clonecanvas->rect) {
       IMB_rect_from_float(s->clonecanvas);
     }
   }
@@ -1492,7 +1549,9 @@ static int paint_2d_canvas_set(ImagePaintState *s, Image *ima)
 
 static void paint_2d_canvas_free(ImagePaintState *s)
 {
-  BKE_image_release_ibuf(s->image, s->canvas, NULL);
+  for (int i = 0; i < s->num_tiles; i++) {
+    BKE_image_release_ibuf(s->image, s->tiles[i].canvas, NULL);
+  }
   BKE_image_release_ibuf(s->brush->clone.image, s->clonecanvas, NULL);
 
   if (s->blurkernel) {
@@ -1501,71 +1560,107 @@ static void paint_2d_canvas_free(ImagePaintState *s)
   }
 }
 
+static void paint_2d_transform_mouse(ImagePaintState *s, const float in[2], float out[2])
+{
+  UI_view2d_region_to_view(s->v2d, in[0], in[1], &out[0], &out[1]);
+}
+
+static bool is_inside_tile(const int size[2], const float pos[2], const float brush[2])
+{
+  return (pos[0] >= -brush[0]) && (pos[0] < size[0] + brush[0]) && (pos[1] >= -brush[1]) &&
+         (pos[1] < size[1] + brush[1]);
+}
+
+static void paint_2d_uv_to_coord(ImagePaintTile *tile, const float uv[2], float coord[2])
+{
+  coord[0] = (uv[0] - tile->uv_origin[0]) * tile->size[0];
+  coord[1] = (uv[1] - tile->uv_origin[1]) * tile->size[1];
+}
+
 void paint_2d_stroke(void *ps,
                      const float prev_mval[2],
                      const float mval[2],
                      const bool eraser,
                      float pressure,
                      float distance,
-                     float size)
+                     float base_size)
 {
-  float newuv[2], olduv[2];
+  float new_uv[2], old_uv[2];
   ImagePaintState *s = ps;
   BrushPainter *painter = s->painter;
-  ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, s->sima ? &s->sima->iuser : NULL, NULL);
-  const bool is_data = (ibuf && ibuf->colormanage_flag & IMB_COLORMANAGE_IS_DATA);
 
-  if (!ibuf) {
-    return;
-  }
+  const bool is_data = s->tiles[0].canvas->colormanage_flag & IMB_COLORMANAGE_IS_DATA;
 
   s->blend = s->brush->blend;
   if (eraser) {
     s->blend = IMB_BLEND_ERASE_ALPHA;
   }
 
-  UI_view2d_region_to_view(s->v2d, mval[0], mval[1], &newuv[0], &newuv[1]);
-  UI_view2d_region_to_view(s->v2d, prev_mval[0], prev_mval[1], &olduv[0], &olduv[1]);
-
-  newuv[0] *= ibuf->x;
-  newuv[1] *= ibuf->y;
-
-  olduv[0] *= ibuf->x;
-  olduv[1] *= ibuf->y;
+  UI_view2d_region_to_view(s->v2d, mval[0], mval[1], &new_uv[0], &new_uv[1]);
+  UI_view2d_region_to_view(s->v2d, prev_mval[0], prev_mval[1], &old_uv[0], &old_uv[1]);
 
+  float last_uv[2], start_uv[2];
+  UI_view2d_region_to_view(s->v2d, 0.0f, 0.0f, &start_uv[0], &start_uv[1]);
   if (painter->firsttouch) {
-    float startuv[2];
-
-    UI_view2d_region_to_view(s->v2d, 0, 0, &startuv[0], &startuv[1]);
-
     /* paint exactly once on first touch */
-    painter->startpaintpos[0] = startuv[0] * ibuf->x;
-    painter->startpaintpos[1] = startuv[1] * ibuf->y;
-
-    painter->firsttouch = 0;
-    copy_v2_v2(painter->lastpaintpos, newuv);
+    copy_v2_v2(last_uv, new_uv);
   }
   else {
-    copy_v2_v2(painter->lastpaintpos, olduv);
+    copy_v2_v2(last_uv, old_uv);
   }
 
-  /* OCIO_TODO: float buffers are now always linear, so always use color correction
-   *            this should probably be changed when texture painting color space is supported
-   */
-  brush_painter_2d_require_imbuf(painter, (ibuf->rect_float != NULL), !is_data);
+  float uv_brush_size[2] = {base_size / s->tiles[0].size[0], base_size / s->tiles[0].size[1]};
+
+  for (int i = 0; i < s->num_tiles; i++) {
+    ImagePaintTile *tile = &s->tiles[i];
+
+    /* First test: Project brush into UV space, clip against tile. */
+    const int uv_size[2] = {1, 1};
+    float local_new_uv[2], local_old_uv[2];
+    sub_v2_v2v2(local_new_uv, new_uv, tile->uv_origin);
+    sub_v2_v2v2(local_old_uv, old_uv, tile->uv_origin);
+    if (!(is_inside_tile(uv_size, local_new_uv, uv_brush_size) ||
+          is_inside_tile(uv_size, local_old_uv, uv_brush_size))) {
+      continue;
+    }
+
+    /* Lazy tile loading to get size in pixels. */
+    if (!paint_2d_ensure_tile_canvas(s, i)) {
+      continue;
+    }
+
+    float size = base_size * tile->radius_fac;
+
+    float new_coord[2], old_coord[2];
+    paint_2d_uv_to_coord(tile, new_uv, new_coord);
+    paint_2d_uv_to_coord(tile, old_uv, old_coord);
+    if (painter->firsttouch) {
+      paint_2d_uv_to_coord(tile, start_uv, tile->start_paintpos);
+    }
+    paint_2d_uv_to_coord(tile, last_uv, tile->last_paintpos);
+
+    /* Second check in pixel coordinates. */
+    const float pixel_brush_size[] = {size, size};
+    if (!(is_inside_tile(tile->size, new_coord, pixel_brush_size) ||
+          is_inside_tile(tile->size, old_coord, pixel_brush_size))) {
+      continue;
+    }
+
+    ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, &tile->iuser, NULL);
 
-  brush_painter_2d_refresh_cache(s, painter, newuv, mval, pressure, distance, size);
+    /* OCIO_TODO: float buffers are now always linear, so always use color correction
+     *            this should probably be changed when texture painting color space is supported
+     */
+    brush_painter_2d_require_imbuf(
+        painter->brush, tile, (ibuf->rect_float != NULL), !is_data, painter->cache_invert);
 
-  if (paint_2d_op(s,
-                  painter->cache.ibuf,
-                  painter->cache.curve_mask,
-                  painter->cache.tex_mask,
-                  olduv,
-                  newuv)) {
-    s->need_redraw = true;
+    brush_painter_2d_refresh_cache(s, painter, tile, new_coord, mval, pressure, distance, size);
+
+    if (paint_2d_op(s, tile, old_coord, new_coord))
+      tile->need_redraw = true;
   }
 
-  BKE_image_release_ibuf(s->image, ibuf, NULL);
+  painter->firsttouch = 0;
 }
 
 void *paint_2d_new_stroke(bContext *C, wmOperator *op, int mode)
@@ -1588,13 +1683,57 @@ void *paint_2d_new_stroke(bContext *C, wmOperator *op, int mode)
   s->image = s->sima->image;
   s->symmetry = settings->imapaint.paint.symmetry_flags;
 
-  if (!paint_2d_canvas_set(s, s->image)) {
-    if (s->warnmultifile) {
-      BKE_report(op->reports, RPT_WARNING, "Image requires 4 color channels to paint");
-    }
-    if (s->warnpackedfile) {
-      BKE_report(op->reports, RPT_WARNING, "Packed MultiLayer files cannot be painted");
-    }
+  if (s->image == NULL) {
+    MEM_freeN(s);
+    return NULL;
+  }
+  if (BKE_image_has_packedfile(s->image) && s->image->rr != NULL) {
+    BKE_report(op->reports, RPT_WARNING, "Packed MultiLayer files cannot be painted");
+    MEM_freeN(s);
+    return 0;
+  }
+
+  s->num_tiles = BLI_listbase_count(&s->image->tiles);
+  s->tiles = MEM_callocN(sizeof(ImagePaintTile) * s->num_tiles, "ImagePaintTile");
+  for (int i = 0; i < s->num_tiles; i++) {
+    BKE_imageuser_default(&s->tiles[i].iuser);
+  }
+  s->tiles[0].iuser.ok = true;
+
+  zero_v2(s->tiles[0].uv_origin);
+
+  ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, &s->tiles[0].iuser, NULL);
+  if (ibuf == NULL) {
+    MEM_freeN(s->tiles);
+    MEM_freeN(s);
+    return NULL;
+  }
+
+  if (ibuf->channels != 4) {
+    BKE_report(op->reports, RPT_WARNING, "Image requires 4 color channels to paint");
+    MEM_freeN(s->tiles);
+    MEM_freeN(s);
+    return NULL;
+  }
+
+  s->tiles[0].size[0] = ibuf->x;
+  s->tiles[0].size[1] = ibuf->y;
+  s->tiles[0].radius_fac = 1.0f;
+
+  s->tiles[0].canvas = ibuf;
+  s->tiles[0].state = PAINT2D_TILE_READY;
+
+  /* Initialize offsets here, they're needed for the uv space clip test before lazy-loading the
+   * tile properly. */
+  int tile_idx = 0;
+  for (ImageTile *tile = s->image->tiles.first; tile; tile = tile->next, tile_idx++) {
+    s->tiles[tile_idx].iuser.tile = tile->tile_number;
+    s->tiles[tile_idx].uv_origin[0] = ((tile->tile_number - 1001) % 10);
+    s->tiles[tile_idx].uv_origin[1] = ((tile->tile_number - 1001) / 10);
+  }
+
+  if (!paint_2d_canvas_set(s)) {
+    MEM_freeN(s->tiles);
 
     MEM_freeN(s);
     return NULL;
@@ -1616,18 +1755,28 @@ void paint_2d_redraw(const bContext *C, void *ps, bool final)
 {
   ImagePaintState *s = ps;
 
-  if (s->need_redraw) {
-    ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, s->sima ? &s->sima->iuser : NULL, NULL);
+  bool had_redraw = false;
+  for (int i = 0; i < s->num_tiles; i++) {
+    if (s->tiles[i].need_redraw) {
+      ImBuf *ibuf = BKE_image_acquire_ibuf(s->image, &s->tiles[i].iuser, NULL);
 
-    imapaint_image_update(s->sima, s->image, ibuf, false);
-    ED_imapaint_clear_partial_redraw();
+      imapaint_image_update(s->sima, s->image, ibuf, &s->tiles[i].iuser, false);
 
-    BKE_image_release_ibuf(s->image, ibuf, NULL);
+      BKE_image_release_ibuf(s->image, ibuf, NULL);
 
-    s->need_redraw = false;
+      s->tiles[i].need_redraw = false;
+      had_redraw = true;
+    }
   }
-  else if (!final) {
-    return;
+
+  if (had_redraw) {
+    ED_imapaint_clear_partial_redraw();
+    if (s->sima == NULL || !s->sima->lock) {
+      ED_region_tag_redraw(CTX_wm_region(C));
+    }
+    else {
+      WM_event_add_notifier(C, NC_IMAGE | NA_PAINTING, s->image);
+    }
   }
 
   if (final) {
@@ -1639,14 +1788,6 @@ void paint_2d_redraw(const bContext *C, void *ps, bool final)
     WM_event_add_notifier(C, NC_IMAGE | NA_EDITED, s->image);
     DEG_id_tag_update(&s->image->id, 0);
   }
-  else {
-    if (!s->sima || !s->sima->lock) {
-      ED_region_tag_redraw(CTX_wm_region(C));
-    }
-    else {
-      WM_event_add_notifier(C, NC_IMAGE | NA_PAINTING, s->image);
-    }
-  }
 }
 
 void paint_2d_stroke_done(void *ps)
@@ -1654,7 +1795,11 @@ void paint_2d_stroke_done(void *ps)
   ImagePaintState *s = ps;
 
   paint_2d_canvas_free(s);
-  brush_painter_2d_free(s->painter);
+  for (int i = 0; i < s->num_tiles; i++) {
+    brush_painter_cache_2d_free(&s->tiles[i].cache);
+  }
+  MEM_freeN(s->painter);
+  MEM_freeN(s->tiles);
   paint_brush_exit_tex(s->brush);
 
   MEM_freeN(s);
@@ -1713,9 +1858,29 @@ static void paint_2d_fill_add_pixel_float(const int x_px,
   }
 }
 
+static ImageUser *paint_2d_get_tile_iuser(ImagePaintState *s, int tile_number)
+{
+  ImageUser *iuser = &s->tiles[0].iuser;
+  for (int i = 0; i < s->num_tiles; i++) {
+    if (s->tiles[i].iuser.tile == tile_number) {
+      if (!paint_2d_ensure_tile_canvas(s, i)) {
+        return NULL;
+      }
+      iuser = &s->tiles[i].iuser;
+      break;
+    }
+  }
+
+  return iuser;
+}
+
 /* this function expects linear space color values */
-void paint_2d_bucket_fill(
-    const bContext *C, const float color[3], Brush *br, const float mouse_init[2], void *ps)
+void paint_2d_bucket_fill(const bContext *C,
+                          const float color[3],
+                          Brush *br,
+                          const float mouse_init[2],
+                          const float mouse_final[2],
+                          void *ps)
 {
   SpaceImage *sima = CTX_wm_space_image(C);
   Image *ima = sima->image;
@@ -1734,8 +1899,17 @@ void paint_2d_bucket_fill(
     return;
   }
 
-  ibuf = BKE_image_acquire_ibuf(ima, &sima->iuser, NULL);
+  float uv_origin[2];
+  float image_init[2];
+  paint_2d_transform_mouse(s, mouse_init, image_init);
 
+  int tile_number = BKE_image_get_tile_from_pos(ima, image_init, image_init, uv_origin);
+  ImageUser *iuser = paint_2d_get_tile_iuser(s, tile_number);
+  if (!iuser) {
+    return;
+  }
+
+  ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
   if (!ibuf) {
     return;
   }
@@ -1753,9 +1927,9 @@ void paint_2d_bucket_fill(
     color_f[3] = strength;
   }
 
-  if (!mouse_init || !br) {
+  if (!mouse_final || !br) {
     /* first case, no image UV, fill the whole image */
-    ED_imapaint_dirty_region(ima, ibuf, 0, 0, ibuf->x, ibuf->y, false);
+    ED_imapaint_dirty_region(ima, ibuf, tile_number, 0, 0, ibuf->x, ibuf->y, false);
 
     if (do_float) {
       for (x_px = 0; x_px < ibuf->x; x_px++) {
@@ -1783,15 +1957,12 @@ void paint_2d_bucket_fill(
     BLI_bitmap *touched;
     size_t coordinate;
     int width = ibuf->x;
-    float image_init[2];
     int minx = ibuf->x, miny = ibuf->y, maxx = 0, maxy = 0;
     float pixel_color[4];
     /* We are comparing to sum of three squared values
      * (assumed in range [0,1]), so need to multiply... */
     float threshold_sq = br->fill_threshold * br->fill_threshold * 3;
 
-    UI_view2d_region_to_view(s->v2d, mouse_init[0], mouse_init[1], &image_init[0], &image_init[1]);
-
     x_px = image_init[0] * ibuf->x;
     y_px = image_init[1] * ibuf->y;
 
@@ -1801,7 +1972,7 @@ void paint_2d_bucket_fill(
     }
 
     /* change image invalidation method later */
-    ED_imapaint_dirty_region(ima, ibuf, 0, 0, ibuf->x, ibuf->y, false);
+    ED_imapaint_dirty_region(ima, ibuf, tile_number, 0, 0, ibuf->x, ibuf->y, false);
 
     stack = BLI_stack_new(sizeof(size_t), __func__);
     touched = BLI_BITMAP_NEW(((size_t)ibuf->x) * ibuf->y, "bucket_fill_bitmap");
@@ -1913,7 +2084,7 @@ void paint_2d_bucket_fill(
     BLI_stack_free(stack);
   }
 
-  imapaint_image_update(sima, ima, ibuf, false);
+  imapaint_image_update(sima, ima, ibuf, iuser, false);
   ED_imapaint_clear_partial_redraw();
 
   BKE_image_release_ibuf(ima, ibuf, NULL);
@@ -1938,19 +2109,26 @@ void paint_2d_gradient_fill(
 
   bool do_float;
 
-  if (!ima) {
+  if (ima == NULL) {
     return;
   }
 
-  ibuf = BKE_image_acquire_ibuf(ima, &sima->iuser, NULL);
+  float uv_origin[2];
+  int tile_number = BKE_image_get_tile_from_pos(ima, image_init, image_init, uv_origin);
+  ImageUser *iuser = paint_2d_get_tile_iuser(s, tile_number);
+  if (!iuser) {
+    return;
+  }
 
-  if (!ibuf) {
+  ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
+  if (ibuf == NULL) {
     return;
   }
 
-  UI_view2d_region_to_view(
-      s->v2d, mouse_final[0], mouse_final[1], &image_final[0], &image_final[1]);
-  UI_view2d_region_to_view(s->v2d, mouse_init[0], mouse_init[1], &image_init[0], &image_init[1]);
+  paint_2d_transform_mouse(s, mouse_final, image_final);
+  paint_2d_transform_mouse(s, mouse_init, image_init);
+  sub_v2_v2(image_init, uv_origin);
+  sub_v2_v2(image_final, uv_origin);
 
   image_final[0] *= ibuf->x;
   image_final[1] *= ibuf->y;
@@ -1967,7 +2145,7 @@ void paint_2d_gradient_fill(
   do_float = (ibuf->rect_float != NULL);
 
   /* this will be substituted by something else when selection is available */
-  ED_imapaint_dirty_region(ima, ibuf, 0, 0, ibuf->x, ibuf->y, false);
+  ED_imapaint_dirty_region(ima, ibuf, tile_number, 0, 0, ibuf->x, ibuf->y, false);
 
   if (do_float) {
     for (x_px = 0; x_px < ibuf->x; x_px++) {
@@ -2027,7 +2205,7 @@ void paint_2d_gradient_fill(
     }
   }
 
-  imapaint_image_update(sima, ima, ibuf, false);
+  imapaint_image_update(sima, ima, ibuf, iuser, false);
   ED_imapaint_clear_partial_redraw();
 
   BKE_image_release_ibuf(ima, ibuf, NULL);
diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index c57490041bc..6a67c469955 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -197,6 +197,7 @@ BLI_INLINE unsigned char f_to_char(const float val)
  */
 typedef struct ProjPaintImage {
   Image *ima;
+  ImageUser iuser;
   ImBuf *ibuf;
   ImagePaintPartialRedraw *partRedrawRect;
   /** Only used to build undo tiles during painting. */
@@ -530,6 +531,18 @@ BLI_INLINE const MPoly *ps_tri_index_to_mpoly(const ProjPaintState *ps, int tri_
 
 /* Finish projection painting structs */
 
+static int project_paint_face_paint_tile(Image *ima, const float *uv)
+{
+  if (ima == NULL || ima->source != IMA_SRC_TILED) {
+    return 0;
+  }
+
+  /* Currently, faces are assumed to belong to one tile, so checking the first loop is enough. */
+  int tx = (int)uv[0];
+  int ty = (int)uv[1];
+  return 1001 + 10 * ty + tx;
+}
+
 static TexPaintSlot *project_paint_face_paint_slot(const ProjPaintState *ps, int tri_index)
 {
   const MPoly *mp = ps_tri_index_to_mpoly(ps, tri_index);
@@ -729,9 +742,17 @@ static bool project_paint_PickColor(const ProjPaintState *ps,
 
   ima = project_paint_face_paint_image(ps, tri_index);
   /** we must have got the imbuf before getting here. */
-  ibuf = BKE_image_get_first_ibuf(ima);
-  if (!ibuf) {
-    return 0;
+  int tile_number = project_paint_face_paint_tile(ima, lt_tri_uv[0]);
+  ImageUser iuser;
+  BKE_imageuser_default(&iuser);
+  iuser.tile = tile_number;
+  ibuf = BKE_image_acquire_ibuf(ima, &iuser, NULL);
+  if (ibuf == NULL) {
+    iuser.tile = 0;
+    ibuf = BKE_image_acquire_ibuf(ima, &iuser, NULL);
+    if (ibuf == NULL) {
+      return 0;
+    }
   }
 
   if (interp) {
@@ -1154,6 +1175,8 @@ static bool check_seam(const ProjPaintState *ps,
         const float *lt_tri_uv[3] = {PS_LOOPTRI_AS_UV_3(ps->poly_to_loop_uv, lt)};
         Image *tpage = project_paint_face_paint_image(ps, tri_index);
         Image *orig_tpage = project_paint_face_paint_image(ps, orig_face);
+        int tile = project_paint_face_paint_tile(tpage, lt_tri_uv[0]);
+        int orig_tile = project_paint_face_paint_tile(orig_tpage, orig_lt_tri_uv[0]);
 
         BLI_assert(i1_fidx != -1);
 
@@ -1171,7 +1194,8 @@ static bool check_seam(const ProjPaintState *ps,
         }
 
         /* first test if they have the same image */
-        if ((orig_tpage == tpage) && cmp_uv(orig_lt_tri_uv[orig_i1_fidx], lt_tri_uv[i1_fidx]) &&
+        if ((orig_tpage == tpage) && (orig_tile == tile) &&
+            cmp_uv(orig_lt_tri_uv[orig_i1_fidx], lt_tri_uv[i1_fidx]) &&
             cmp_uv(orig_lt_tri_uv[orig_i2_fidx], lt_tri_uv[i2_fidx])) {
           /* if faces don't have the same winding in uv space,
            * they are on the same side so edge is boundary */
@@ -1817,6 +1841,7 @@ static int project_paint_undo_subtiles(const TileInfo *tinf, int tx, int ty)
                                           pjIma->ima,
                                           pjIma->ibuf,
                                           tinf->tmpibuf,
+                                          pjIma->iuser.tile,
                                           tx,
                                           ty,
                                           &pjIma->maskRect[tile_index],
@@ -1829,6 +1854,7 @@ static int project_paint_undo_subtiles(const TileInfo *tinf, int tx, int ty)
                                           pjIma->ima,
                                           pjIma->ibuf,
                                           tinf->tmpibuf,
+                                          pjIma->iuser.tile,
                                           tx,
                                           ty,
                                           NULL,
@@ -3486,6 +3512,7 @@ static void project_bucket_init(const ProjPaintState *ps,
   ImBuf *ibuf = NULL;
   Image *tpage_last = NULL, *tpage;
   ImBuf *tmpibuf = NULL;
+  int tile_last = 0;
 
   if (ps->image_tot == 1) {
     /* Simple loop, no context switching */
@@ -3509,17 +3536,34 @@ static void project_bucket_init(const ProjPaintState *ps,
     for (node = ps->bucketFaces[bucket_index]; node; node = node->next) {
       tri_index = POINTER_AS_INT(node->link);
 
+      const MLoopTri *lt = &ps->mlooptri_eval[tri_index];
+      const float *lt_tri_uv[3] = {PS_LOOPTRI_AS_UV_3(ps->poly_to_loop_uv, lt)};
+
       /* Image context switching */
       tpage = project_paint_face_paint_image(ps, tri_index);
-      if (tpage_last != tpage) {
+      int tile = project_paint_face_paint_tile(tpage, lt_tri_uv[0]);
+      if (tpage_last != tpage || tile_last != tile) {
         tpage_last = tpage;
+        tile_last = tile;
 
+        ibuf = NULL;
         for (image_index = 0; image_index < ps->image_tot; image_index++) {
-          if (ps->projImages[image_index].ima == tpage_last) {
-            ibuf = ps->projImages[image_index].ibuf;
+          ProjPaintImage *projIma = &ps->projImages[image_index];
+          if ((projIma->ima == tpage) && (projIma->iuser.tile == tile)) {
+            ibuf = projIma->ibuf;
             break;
           }
         }
+        if (ibuf == NULL) {
+          /* Failed to find the specific tile, fall back to the primary tile. */
+          for (image_index = 0; image_index < ps->image_tot; image_index++) {
+            ProjPaintImage *projIma = &ps->projImages[image_index];
+            if ((projIma->ima == tpage) && (projIma->iuser.tile == 0)) {
+              ibuf = projIma->ibuf;
+              break;
+            }
+          }
+        }
       }
       /* context switching done */
 
@@ -4232,22 +4276,36 @@ static bool project_paint_winclip(const ProjPaintState *ps, const ProjPaintFaceC
 }
 #endif  // PROJ_DEBUG_WINCLIP
 
+typedef struct PrepareImageEntry {
+  struct PrepareImageEntry *next, *prev;
+  Image *ima;
+  int tile;
+} PrepareImageEntry;
+
 static void project_paint_build_proj_ima(ProjPaintState *ps,
                                          MemArena *arena,
-                                         LinkNode *image_LinkList)
+                                         ListBase *used_images)
 {
   ProjPaintImage *projIma;
-  LinkNode *node;
+  PrepareImageEntry *entry;
   int i;
 
   /* build an array of images we use */
   projIma = ps->projImages = BLI_memarena_alloc(arena, sizeof(ProjPaintImage) * ps->image_tot);
 
-  for (node = image_LinkList, i = 0; node; node = node->next, i++, projIma++) {
+  for (entry = used_images->first, i = 0; entry; entry = entry->next, i++, projIma++) {
+    memset(&projIma->iuser, 0, sizeof(ImageUser));
+    BKE_imageuser_default(&projIma->iuser);
+    projIma->iuser.tile = entry->tile;
     int size;
-    projIma->ima = node->link;
+    projIma->ima = entry->ima;
     projIma->touch = 0;
-    projIma->ibuf = BKE_image_acquire_ibuf(projIma->ima, NULL, NULL);
+    projIma->ibuf = BKE_image_acquire_ibuf(projIma->ima, &projIma->iuser, NULL);
+    if (projIma->ibuf == NULL) {
+      projIma->iuser.tile = 0;
+      projIma->ibuf = BKE_image_acquire_ibuf(projIma->ima, &projIma->iuser, NULL);
+      BLI_assert(projIma->ibuf != NULL);
+    }
     size = sizeof(void **) * ED_IMAGE_UNDO_TILE_NUMBER(projIma->ibuf->x) *
            ED_IMAGE_UNDO_TILE_NUMBER(projIma->ibuf->y);
     projIma->partRedrawRect = BLI_memarena_alloc(
@@ -4270,15 +4328,18 @@ static void project_paint_prepare_all_faces(ProjPaintState *ps,
                                             const bool is_multi_view)
 {
   /* Image Vars - keep track of images we have used */
-  LinkNodePair image_LinkList = {NULL, NULL};
+  ListBase used_images = {NULL};
 
   Image *tpage_last = NULL, *tpage;
   TexPaintSlot *slot_last = NULL;
   TexPaintSlot *slot = NULL;
+  int tile_last = -1, tile;
   const MLoopTri *lt;
   int image_index = -1, tri_index;
   int prev_poly = -1;
 
+  BLI_assert(ps->image_tot == 0);
+
   for (tri_index = 0, lt = ps->mlooptri_eval; tri_index < ps->totlooptri_eval; tri_index++, lt++) {
     bool is_face_sel;
     bool skip_tri = false;
@@ -4321,6 +4382,8 @@ static void project_paint_prepare_all_faces(ProjPaintState *ps,
 
     ps->poly_to_loop_uv[lt->poly] = mloopuv_base;
 
+    tile = project_paint_face_paint_tile(tpage, mloopuv_base[lt->tri[0]].uv);
+
 #ifndef PROJ_DEBUG_NOSEAMBLEED
     project_paint_bleed_add_face_user(ps, arena, lt, tri_index);
 #endif
@@ -4382,18 +4445,24 @@ static void project_paint_prepare_all_faces(ProjPaintState *ps,
         }
       }
 
-      if (tpage_last != tpage) {
-
-        image_index = BLI_linklist_index(image_LinkList.list, tpage);
+      if (tpage_last != tpage || tile_last != tile) {
+        image_index = 0;
+        for (PrepareImageEntry *e = used_images.first; e; e = e->next, image_index++) {
+          if (e->ima == tpage && e->tile == tile) {
+            break;
+          }
+        }
 
-        if (image_index == -1 && BKE_image_has_ibuf(tpage, NULL)) {
-          /* MemArena doesn't have an append func */
-          BLI_linklist_append(&image_LinkList, tpage);
-          image_index = ps->image_tot;
+        if (image_index == ps->image_tot) {
+          PrepareImageEntry *e = MEM_callocN(sizeof(PrepareImageEntry), "PrepareImageEntry");
+          e->ima = tpage;
+          e->tile = tile;
+          BLI_addtail(&used_images, e);
           ps->image_tot++;
         }
 
         tpage_last = tpage;
+        tile_last = tile;
       }
 
       if (image_index != -1) {
@@ -4406,11 +4475,11 @@ static void project_paint_prepare_all_faces(ProjPaintState *ps,
 
   /* build an array of images we use*/
   if (ps->is_shared_user == false) {
-    project_paint_build_proj_ima(ps, arena, image_LinkList.list);
+    project_paint_build_proj_ima(ps, arena, &used_images);
   }
 
   /* we have built the array, discard the linked list */
-  BLI_linklist_free(image_LinkList.list, NULL);
+  BLI_freelistN(&used_images);
 }
 
 /* run once per stroke before projection painting */
@@ -4675,7 +4744,7 @@ static bool project_image_refresh_tagged(ProjPaintState *ps)
         pr = &(projIma->partRedrawRect[i]);
         if (pr->x2 != -1) { /* TODO - use 'enabled' ? */
           set_imapaintpartial(pr);
-          imapaint_image_update(NULL, projIma->ima, projIma->ibuf, true);
+          imapaint_image_update(NULL, projIma->ima, projIma->ibuf, &projIma->iuser, true);
           redraw = 1;
         }
 
@@ -6441,7 +6510,8 @@ static Image *proj_paint_image_create(wmOperator *op, Main *bmain, bool is_data)
                                 gen_type,
                                 color,
                                 false,
-                                is_data);
+                                is_data,
+                                false); /* TODO(lukas): Add option */
 
   return ima;
 }
diff --git a/source/blender/editors/sculpt_paint/paint_intern.h b/source/blender/editors/sculpt_paint/paint_intern.h
index 84665728e17..53beb981522 100644
--- a/source/blender/editors/sculpt_paint/paint_intern.h
+++ b/source/blender/editors/sculpt_paint/paint_intern.h
@@ -186,6 +186,7 @@ bool image_texture_paint_poll(struct bContext *C);
 void imapaint_image_update(struct SpaceImage *sima,
                            struct Image *image,
                            struct ImBuf *ibuf,
+                           struct ImageUser *iuser,
                            short texpaint);
 struct ImagePaintPartialRedraw *get_imapaintpartial(void);
 void set_imapaintpartial(struct ImagePaintPartialRedraw *ippr);
@@ -206,6 +207,7 @@ void paint_2d_bucket_fill(const struct bContext *C,
                           const float color[3],
                           struct Brush *br,
                           const float mouse_init[2],
+                          const float mouse_final[2],
                           void *ps);
 void paint_2d_gradient_fill(const struct bContext *C,
                             struct Brush *br,
diff --git a/source/blender/editors/space_clip/clip_draw.c b/source/blender/editors/space_clip/clip_draw.c
index 74cf28ce5d4..f9899135e2d 100644
--- a/source/blender/editors/space_clip/clip_draw.c
+++ b/source/blender/editors/space_clip/clip_draw.c
@@ -1947,7 +1947,7 @@ void clip_draw_main(const bContext *C, SpaceClip *sc, ARegion *ar)
 
   /* if no clip, nothing to do */
   if (!clip) {
-    ED_region_grid_draw(ar, zoomx, zoomy);
+    ED_region_grid_draw(ar, zoomx, zoomy, 0.0f, 0.0f);
     return;
   }
 
@@ -1994,7 +1994,7 @@ void clip_draw_main(const bContext *C, SpaceClip *sc, ARegion *ar)
     draw_movieclip_muted(ar, width, height, zoomx, zoomy);
   }
   else {
-    ED_region_grid_draw(ar, zoomx, zoomy);
+    ED_region_grid_draw(ar, zoomx, zoomy, 0.0f, 0.0f);
   }
 
   if (width && height) {
diff --git a/source/blender/editors/space_image/image_draw.c b/source/blender/editors/space_image/image_draw.c
index 2d4ca6dc15a..9a633427d82 100644
--- a/source/blender/editors/space_image/image_draw.c
+++ b/source/blender/editors/space_image/image_draw.c
@@ -37,6 +37,7 @@
 
 #include "PIL_time.h"
 
+#include "BLI_listbase.h"
 #include "BLI_math.h"
 #include "BLI_rect.h"
 #include "BLI_threads.h"
@@ -531,6 +532,36 @@ static void sima_draw_zbuffloat_pixels(Scene *scene,
   MEM_freeN(rectf);
 }
 
+static void draw_udim_label(ARegion *ar, float fx, float fy, const char *label)
+{
+  if (label == NULL || !label[0]) {
+    return;
+  }
+
+  /* find window pixel coordinates of origin */
+  int x, y;
+  UI_view2d_view_to_region(&ar->v2d, fx, fy, &x, &y);
+
+  GPU_blend_set_func_separate(
+      GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
+  GPU_blend(true);
+
+  int textwidth = BLF_width(blf_mono_font, label, strlen(label)) + 10;
+  float stepx = BLI_rcti_size_x(&ar->v2d.mask) / BLI_rctf_size_x(&ar->v2d.cur);
+  float opacity;
+  if (textwidth < 0.5f * (stepx - 10))
+    opacity = 1.0f;
+  else if (textwidth < (stepx - 10))
+    opacity = 2.0f - 2.0f * (textwidth / (stepx - 10));
+  else
+    opacity = 0.0f;
+  BLF_color4ub(blf_mono_font, 220, 220, 220, 150 * opacity);
+  BLF_position(blf_mono_font, (int)(x + 10), (int)(y + 10), 0);
+  BLF_draw_ascii(blf_mono_font, label, strlen(label));
+
+  GPU_blend(false);
+}
+
 static void draw_image_buffer(const bContext *C,
                               SpaceImage *sima,
                               ARegion *ar,
@@ -760,6 +791,83 @@ static void draw_image_paint_helpers(
   }
 }
 
+static void draw_udim_tile_grid(unsigned int pos_attr,
+                                unsigned int color_attr,
+                                ARegion *ar,
+                                int x,
+                                int y,
+                                float stepx,
+                                float stepy,
+                                const float color[3])
+{
+  float x1, y1;
+  UI_view2d_view_to_region_fl(&ar->v2d, x, y, &x1, &y1);
+  int gridpos[5][2] = {{0, 0}, {0, 1}, {1, 1}, {1, 0}, {0, 0}};
+  for (int i = 0; i < 4; i++) {
+    immAttr3fv(color_attr, color);
+    immVertex2f(pos_attr, x1 + gridpos[i][0] * stepx, y1 + gridpos[i][1] * stepy);
+    immAttr3fv(color_attr, color);
+    immVertex2f(pos_attr, x1 + gridpos[i + 1][0] * stepx, y1 + gridpos[i + 1][1] * stepy);
+  }
+}
+
+static void draw_udim_tile_grids(ARegion *ar, SpaceImage *sima, Image *ima)
+{
+  int num_tiles;
+  if (ima != NULL) {
+    num_tiles = BLI_listbase_count(&ima->tiles);
+
+    if (ima->source != IMA_SRC_TILED) {
+      return;
+    }
+  }
+  else {
+    num_tiles = sima->tile_grid_shape[0] * sima->tile_grid_shape[1];
+  }
+
+  float stepx = BLI_rcti_size_x(&ar->v2d.mask) / BLI_rctf_size_x(&ar->v2d.cur);
+  float stepy = BLI_rcti_size_y(&ar->v2d.mask) / BLI_rctf_size_y(&ar->v2d.cur);
+
+  GPUVertFormat *format = immVertexFormat();
+  unsigned int pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  unsigned color = GPU_vertformat_attr_add(format, "color", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
+
+  immBindBuiltinProgram(GPU_SHADER_2D_FLAT_COLOR);
+  immBegin(GPU_PRIM_LINES, 8 * num_tiles);
+
+  float theme_color[3], selected_color[3];
+  UI_GetThemeColorShade3fv(TH_BACK, 60.0f, theme_color);
+  UI_GetThemeColor3fv(TH_FACE_SELECT, selected_color);
+
+  if (ima != NULL) {
+    ImageTile *cur_tile = BLI_findlink(&ima->tiles, ima->active_tile_index);
+
+    LISTBASE_FOREACH (ImageTile *, tile, &ima->tiles) {
+      if (tile != cur_tile) {
+        int x = (tile->tile_number - 1001) % 10;
+        int y = (tile->tile_number - 1001) / 10;
+        draw_udim_tile_grid(pos, color, ar, x, y, stepx, stepy, theme_color);
+      }
+    }
+
+    if (cur_tile != NULL) {
+      int cur_x = (cur_tile->tile_number - 1001) % 10;
+      int cur_y = (cur_tile->tile_number - 1001) / 10;
+      draw_udim_tile_grid(pos, color, ar, cur_x, cur_y, stepx, stepy, selected_color);
+    }
+  }
+  else {
+    for (int y = 0; y < sima->tile_grid_shape[1]; y++) {
+      for (int x = 0; x < sima->tile_grid_shape[0]; x++) {
+        draw_udim_tile_grid(pos, color, ar, x, y, stepx, stepy, theme_color);
+      }
+    }
+  }
+
+  immEnd();
+  immUnbindProgram();
+}
+
 /* draw main image region */
 
 void draw_image_main(const bContext *C, ARegion *ar)
@@ -827,18 +935,43 @@ void draw_image_main(const bContext *C, ARegion *ar)
     }
   }
 
-  ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  ibuf = ED_space_image_acquire_buffer(sima, &lock, 0);
+
+  int main_w = 0;
+  int main_h = 0;
 
   /* draw the image or grid */
   if (ibuf == NULL) {
-    ED_region_grid_draw(ar, zoomx, zoomy);
+    if (ima != NULL) {
+      LISTBASE_FOREACH (ImageTile *, tile, &ima->tiles) {
+        int x = (tile->tile_number - 1001) % 10;
+        int y = (tile->tile_number - 1001) / 10;
+        ED_region_grid_draw(ar, zoomx, zoomy, x, y);
+      }
+    }
+    else {
+      for (int y = 0; y < sima->tile_grid_shape[1]; y++) {
+        for (int x = 0; x < sima->tile_grid_shape[0]; x++) {
+          ED_region_grid_draw(ar, zoomx, zoomy, x, y);
+        }
+      }
+    }
   }
   else {
     if (sima->flag & SI_DRAW_TILE) {
       draw_image_buffer_repeated(C, sima, ar, scene, ibuf, zoomx, zoomy);
     }
     else {
+      main_w = ibuf->x;
+      main_h = ibuf->y;
+
       draw_image_buffer(C, sima, ar, scene, ibuf, 0.0f, 0.0f, zoomx, zoomy);
+      if (ima->source == IMA_SRC_TILED) {
+        ImageTile *tile = BKE_image_get_tile(ima, 0);
+        char label[sizeof(tile->label)];
+        BKE_image_get_tile_label(ima, tile, label, sizeof(label));
+        draw_udim_label(ar, 0.0f, 0.0f, label);
+      }
     }
 
     if (sima->flag & SI_DRAW_METADATA) {
@@ -854,6 +987,30 @@ void draw_image_main(const bContext *C, ARegion *ar)
 
   ED_space_image_release_buffer(sima, ibuf, lock);
 
+  if (ima != NULL && ima->source == IMA_SRC_TILED) {
+    LISTBASE_FOREACH (ImageTile *, tile, &ima->tiles) {
+      if (tile->tile_number == 1001) {
+        continue;
+      }
+
+      ibuf = ED_space_image_acquire_buffer(sima, &lock, tile->tile_number);
+      if (ibuf != NULL) {
+        int x_pos = (tile->tile_number - 1001) % 10;
+        int y_pos = (tile->tile_number - 1001) / 10;
+        char label[sizeof(tile->label)];
+        BKE_image_get_tile_label(ima, tile, label, sizeof(label));
+
+        float tile_zoomx = (zoomx * main_w) / ibuf->x;
+        float tile_zoomy = (zoomy * main_h) / ibuf->y;
+        draw_image_buffer(C, sima, ar, scene, ibuf, x_pos, y_pos, tile_zoomx, tile_zoomy);
+        draw_udim_label(ar, x_pos, y_pos, label);
+      }
+      ED_space_image_release_buffer(sima, ibuf, lock);
+    }
+  }
+
+  draw_udim_tile_grids(ar, sima, ima);
+
   /* paint helpers */
   if (show_paint) {
     draw_image_paint_helpers(C, ar, scene, zoomx, zoomy);
diff --git a/source/blender/editors/space_image/image_edit.c b/source/blender/editors/space_image/image_edit.c
index ec2b1cc7fbe..c1ed049130e 100644
--- a/source/blender/editors/space_image/image_edit.c
+++ b/source/blender/editors/space_image/image_edit.c
@@ -136,7 +136,7 @@ void ED_space_image_set_mask(bContext *C, SpaceImage *sima, Mask *mask)
   }
 }
 
-ImBuf *ED_space_image_acquire_buffer(SpaceImage *sima, void **r_lock)
+ImBuf *ED_space_image_acquire_buffer(SpaceImage *sima, void **r_lock, int tile)
 {
   ImBuf *ibuf;
 
@@ -148,7 +148,9 @@ ImBuf *ED_space_image_acquire_buffer(SpaceImage *sima, void **r_lock)
     else
 #endif
     {
+      sima->iuser.tile = tile;
       ibuf = BKE_image_acquire_ibuf(sima->image, &sima->iuser, r_lock);
+      sima->iuser.tile = 0;
     }
 
     if (ibuf) {
@@ -179,7 +181,7 @@ bool ED_space_image_has_buffer(SpaceImage *sima)
   void *lock;
   bool has_buffer;
 
-  ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  ibuf = ED_space_image_acquire_buffer(sima, &lock, 0);
   has_buffer = (ibuf != NULL);
   ED_space_image_release_buffer(sima, ibuf, lock);
 
@@ -192,7 +194,8 @@ void ED_space_image_get_size(SpaceImage *sima, int *width, int *height)
   ImBuf *ibuf;
   void *lock;
 
-  ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  /* TODO(lukas): Support tiled images with different sizes */
+  ibuf = ED_space_image_acquire_buffer(sima, &lock, 0);
 
   if (ibuf && ibuf->x > 0 && ibuf->y > 0) {
     *width = ibuf->x;
diff --git a/source/blender/editors/space_image/image_intern.h b/source/blender/editors/space_image/image_intern.h
index f8ce065d46c..f3ec68db562 100644
--- a/source/blender/editors/space_image/image_intern.h
+++ b/source/blender/editors/space_image/image_intern.h
@@ -89,6 +89,10 @@ void IMAGE_OT_read_viewlayers(struct wmOperatorType *ot);
 void IMAGE_OT_render_border(struct wmOperatorType *ot);
 void IMAGE_OT_clear_render_border(struct wmOperatorType *ot);
 
+void IMAGE_OT_tile_add(struct wmOperatorType *ot);
+void IMAGE_OT_tile_remove(struct wmOperatorType *ot);
+void IMAGE_OT_tile_fill(struct wmOperatorType *ot);
+
 /* image_panels.c */
 struct ImageUser *ntree_get_active_iuser(struct bNodeTree *ntree);
 void image_buttons_register(struct ARegionType *art);
diff --git a/source/blender/editors/space_image/image_ops.c b/source/blender/editors/space_image/image_ops.c
index 8d17b703449..4404f904891 100644
--- a/source/blender/editors/space_image/image_ops.c
+++ b/source/blender/editors/space_image/image_ops.c
@@ -35,7 +35,10 @@
 #include "MEM_guardedalloc.h"
 
 #include "BLI_blenlib.h"
+#include "BLI_fileops.h"
+#include "BLI_fileops_types.h"
 #include "BLI_ghash.h"
+#include "BLI_linklist.h"
 #include "BLI_math.h"
 #include "BLI_string.h"
 #include "BLI_utildefines.h"
@@ -1264,6 +1267,51 @@ static int image_cmp_frame(const void *a, const void *b)
   return 0;
 }
 
+static int image_get_udim(const char *filepath, LinkNodePair *udim_tiles)
+{
+  char filename[FILE_MAX], dirname[FILE_MAXDIR];
+  BLI_split_dirfile(filepath, dirname, filename, sizeof(dirname), sizeof(filename));
+
+  if (strstr(filename, "1001") == NULL) {
+    return 0;
+  }
+
+  bool is_udim = true;
+  int max_udim = 0;
+
+  unsigned short digits;
+  char base_head[FILE_MAX], base_tail[FILE_MAX];
+  int id = BLI_stringdec(filename, base_head, base_tail, &digits);
+  if (id == 1001) {
+    struct direntry *dir;
+    uint totfile = BLI_filelist_dir_contents(dirname, &dir);
+    for (int i = 0; i < totfile; i++) {
+      if (!(dir[i].type & S_IFREG)) {
+        continue;
+      }
+      char head[FILE_MAX], tail[FILE_MAX];
+      id = BLI_stringdec(dir[i].relname, head, tail, &digits);
+
+      if (digits > 4 || !(STREQLEN(base_head, head, FILE_MAX)) ||
+          !(STREQLEN(base_tail, tail, FILE_MAX))) {
+        continue;
+      }
+
+      if (id < 1001 || id >= 2000) {
+        is_udim = false;
+        break;
+      }
+
+      BLI_linklist_append(udim_tiles, POINTER_FROM_INT(id));
+      max_udim = max_ii(max_udim, id);
+    }
+
+    BLI_filelist_free(dir, totfile);
+  }
+
+  return is_udim ? (max_udim - 1001) : 0;
+}
+
 /**
  * Return the start (offset) and the length of the sequence of
  * continuous frames in the list of frames.
@@ -1272,21 +1320,27 @@ static int image_cmp_frame(const void *a, const void *b)
  * \param ofs: [out] offset the first frame number in the sequence.
  * \return the number of contiguous frames in the sequence
  */
-static int image_sequence_get_len(ListBase *frames, int *ofs)
+static int image_sequence_get_len(ImageFrameRange *frame_range, int *ofs, LinkNodePair *udim_tiles)
 {
   ImageFrame *frame;
 
-  BLI_listbase_sort(frames, image_cmp_frame);
+  BLI_listbase_sort(&frame_range->frames, image_cmp_frame);
 
-  frame = frames->first;
-  if (frame) {
+  frame = frame_range->frames.first;
+  if (frame != NULL) {
     int frame_curr = frame->framenr;
     (*ofs) = frame_curr;
-    while (frame && (frame->framenr == frame_curr)) {
-      frame_curr++;
-      frame = frame->next;
+
+    if (udim_tiles != NULL && (frame_curr == 1001)) {
+      return 1 + image_get_udim(frame_range->filepath, udim_tiles);
+    }
+    else {
+      while (frame != NULL && (frame->framenr == frame_curr)) {
+        frame_curr++;
+        frame = frame->next;
+      }
+      return frame_curr - (*ofs);
     }
-    return frame_curr - (*ofs);
   }
   *ofs = 0;
   return 0;
@@ -1298,7 +1352,9 @@ static Image *image_open_single(Main *bmain,
                                 const char *relbase,
                                 bool is_relative_path,
                                 bool use_multiview,
-                                int frame_seq_len)
+                                int frame_seq_len,
+                                int frame_seq_ofs,
+                                LinkNodePair *udim_tiles)
 {
   bool exists = false;
   Image *ima = NULL;
@@ -1339,7 +1395,15 @@ static Image *image_open_single(Main *bmain,
     }
 
     if ((frame_seq_len > 1) && (ima->source == IMA_SRC_FILE)) {
-      ima->source = IMA_SRC_SEQUENCE;
+      if (udim_tiles && frame_seq_ofs == 1001) {
+        ima->source = IMA_SRC_TILED;
+        for (LinkNode *node = udim_tiles->list; node; node = node->next) {
+          BKE_image_add_tile(ima, POINTER_AS_INT(node->link), NULL);
+        }
+      }
+      else {
+        ima->source = IMA_SRC_SEQUENCE;
+      }
     }
   }
 
@@ -1358,9 +1422,11 @@ static int image_open_exec(bContext *C, wmOperator *op)
   char filepath[FILE_MAX];
   int frame_seq_len = 0;
   int frame_ofs = 1;
+  LinkNodePair udim_tiles = {NULL};
 
   const bool is_relative_path = RNA_boolean_get(op->ptr, "relative_path");
   const bool use_multiview = RNA_boolean_get(op->ptr, "use_multiview");
+  const bool use_udim = RNA_boolean_get(op->ptr, "use_udim_detecting");
 
   if (!op->customdata) {
     image_open_init(C, op);
@@ -1378,7 +1444,10 @@ static int image_open_exec(bContext *C, wmOperator *op)
     for (ImageFrameRange *frame_range = frame_ranges_all.first; frame_range;
          frame_range = frame_range->next) {
       int frame_range_ofs;
-      int frame_range_seq_len = image_sequence_get_len(&frame_range->frames, &frame_range_ofs);
+
+      LinkNodePair *udim_tiles_ptr = use_udim ? (&udim_tiles) : NULL;
+      int frame_range_seq_len = image_sequence_get_len(
+          frame_range, &frame_range_ofs, udim_tiles_ptr);
       BLI_freelistN(&frame_range->frames);
 
       char filepath_range[FILE_MAX];
@@ -1394,7 +1463,9 @@ static int image_open_exec(bContext *C, wmOperator *op)
                                            BKE_main_blendfile_path(bmain),
                                            is_relative_path,
                                            use_multiview,
-                                           frame_range_seq_len);
+                                           frame_range_seq_len,
+                                           frame_range_ofs,
+                                           udim_tiles_ptr);
 
       /* take the first image */
       if ((ima == NULL) && ima_range) {
@@ -1407,10 +1478,31 @@ static int image_open_exec(bContext *C, wmOperator *op)
   }
   else {
     /* for drag & drop etc. */
-    ima = image_open_single(
-        bmain, op, filepath, BKE_main_blendfile_path(bmain), is_relative_path, use_multiview, 1);
+    frame_seq_len = 1;
+
+    if (use_udim) {
+      /* Try to find UDIM tiles corresponding to the image */
+      frame_seq_len = 1 + image_get_udim(filepath, &udim_tiles);
+
+      /* If we found something, mark the image as tiled. */
+      if (frame_seq_len > 1) {
+        frame_ofs = 1001;
+      }
+    }
+
+    ima = image_open_single(bmain,
+                            op,
+                            filepath,
+                            BKE_main_blendfile_path(bmain),
+                            is_relative_path,
+                            use_multiview,
+                            frame_seq_len,
+                            frame_ofs,
+                            &udim_tiles);
   }
 
+  BLI_linklist_free(udim_tiles.list, NULL);
+
   if (ima == NULL) {
     return OPERATOR_CANCELLED;
   }
@@ -1458,7 +1550,8 @@ static int image_open_exec(bContext *C, wmOperator *op)
 
   /* initialize because of new image */
   if (iuser) {
-    iuser->frames = frame_seq_len;
+    /* If the sequence was a tiled image, we only have one frame. */
+    iuser->frames = (ima->source == IMA_SRC_SEQUENCE) ? frame_seq_len : 1;
     iuser->sfra = 1;
     iuser->framenr = 1;
     if (ima->source == IMA_SRC_MOVIE) {
@@ -1604,6 +1697,11 @@ void IMAGE_OT_open(wmOperatorType *ot)
       true,
       "Detect Sequences",
       "Automatically detect animated sequences in selected images (based on file names)");
+  RNA_def_boolean(ot->srna,
+                  "use_udim_detecting",
+                  true,
+                  "Detect UDIMs",
+                  "Detect selected UDIM files and load all matching tiles");
 }
 
 /** \} */
@@ -1870,6 +1968,12 @@ static int image_save_options_init(Main *bmain,
         BLI_path_make_safe(opts->filepath);
         BLI_path_abs(opts->filepath, is_prev_save ? G.ima : BKE_main_blendfile_path(bmain));
       }
+
+      /* append UDIM numbering if not present */
+      if (ima->source == IMA_SRC_TILED && (BLI_stringdec(ima->name, NULL, NULL, NULL) != 1001)) {
+        int len = strlen(opts->filepath);
+        STR_CONCAT(opts->filepath, len, ".1001");
+      }
     }
 
     /* color management */
@@ -2608,13 +2712,23 @@ static int image_new_exec(bContext *C, wmOperator *op)
   RNA_float_get_array(op->ptr, "color", color);
   alpha = RNA_boolean_get(op->ptr, "alpha");
   stereo3d = RNA_boolean_get(op->ptr, "use_stereo_3d");
+  bool tiled = RNA_boolean_get(op->ptr, "tiled");
 
   if (!alpha) {
     color[3] = 1.0f;
   }
 
-  ima = BKE_image_add_generated(
-      bmain, width, height, name, alpha ? 32 : 24, floatbuf, gen_type, color, stereo3d, false);
+  ima = BKE_image_add_generated(bmain,
+                                width,
+                                height,
+                                name,
+                                alpha ? 32 : 24,
+                                floatbuf,
+                                gen_type,
+                                color,
+                                stereo3d,
+                                false,
+                                tiled);
 
   if (!ima) {
     image_new_free(op);
@@ -2698,6 +2812,9 @@ static void image_new_draw(bContext *UNUSED(C), wmOperator *op)
   uiItemL(col[0], "", ICON_NONE);
   uiItemR(col[1], &ptr, "float", 0, NULL, ICON_NONE);
 
+  uiItemL(col[0], "", ICON_NONE);
+  uiItemR(col[1], &ptr, "tiled", 0, NULL, ICON_NONE);
+
 #if 0
   if (is_multiview) {
     uiItemL(col[0], "", ICON_NONE);
@@ -2753,6 +2870,8 @@ void IMAGE_OT_new(wmOperatorType *ot)
   prop = RNA_def_boolean(
       ot->srna, "use_stereo_3d", 0, "Stereo 3D", "Create an image with left and right views");
   RNA_def_property_flag(prop, PROP_SKIP_SAVE | PROP_HIDDEN);
+  prop = RNA_def_boolean(ot->srna, "tiled", 0, "Tiled", "Create a tiled image");
+  RNA_def_property_flag(prop, PROP_SKIP_SAVE);
 }
 
 #undef IMA_DEF_NAME
@@ -2783,7 +2902,7 @@ static int image_invert_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  ED_image_undo_push_begin_with_image(op->type->name, ima, ibuf);
+  ED_image_undo_push_begin_with_image(op->type->name, ima, ibuf, 0);
 
   if (is_paint) {
     ED_imapaint_clear_partial_redraw();
@@ -2927,7 +3046,7 @@ static int image_scale_exec(bContext *C, wmOperator *op)
     RNA_property_int_set_array(op->ptr, prop, size);
   }
 
-  ED_image_undo_push_begin_with_image(op->type->name, ima, ibuf);
+  ED_image_undo_push_begin_with_image(op->type->name, ima, ibuf, 0);
 
   ibuf->userflags |= IB_DISPLAY_BUFFER_INVALID;
   IMB_scaleImBuf(ibuf, size[0], size[1]);
@@ -2977,7 +3096,7 @@ static bool image_pack_test(bContext *C, wmOperator *op)
     return 0;
   }
 
-  if (ima->source == IMA_SRC_SEQUENCE || ima->source == IMA_SRC_MOVIE) {
+  if (ELEM(ima->source, IMA_SRC_SEQUENCE, IMA_SRC_MOVIE, IMA_SRC_TILED)) {
     BKE_report(op->reports, RPT_ERROR, "Packing movies or image sequences not supported");
     return 0;
   }
@@ -3045,7 +3164,7 @@ static int image_unpack_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  if (ima->source == IMA_SRC_SEQUENCE || ima->source == IMA_SRC_MOVIE) {
+  if (ELEM(ima->source, IMA_SRC_SEQUENCE, IMA_SRC_MOVIE, IMA_SRC_TILED)) {
     BKE_report(op->reports, RPT_ERROR, "Unpacking movies or image sequences not supported");
     return OPERATOR_CANCELLED;
   }
@@ -3078,7 +3197,7 @@ static int image_unpack_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSE
     return OPERATOR_CANCELLED;
   }
 
-  if (ima->source == IMA_SRC_SEQUENCE || ima->source == IMA_SRC_MOVIE) {
+  if (ELEM(ima->source, IMA_SRC_SEQUENCE, IMA_SRC_MOVIE, IMA_SRC_TILED)) {
     BKE_report(op->reports, RPT_ERROR, "Unpacking movies or image sequences not supported");
     return OPERATOR_CANCELLED;
   }
@@ -3210,9 +3329,12 @@ static void image_sample_draw(const bContext *C, ARegion *ar, void *arg_info)
 /* Returns color in linear space, matching ED_space_node_color_sample(). */
 bool ED_space_image_color_sample(SpaceImage *sima, ARegion *ar, int mval[2], float r_col[3])
 {
+  float uv[2];
+  UI_view2d_region_to_view(&ar->v2d, mval[0], mval[1], &uv[0], &uv[1]);
+  int tile = BKE_image_get_tile_from_pos(sima->image, uv, uv, NULL);
+
   void *lock;
-  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock);
-  float fx, fy;
+  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock, tile);
   bool ret = false;
 
   if (ibuf == NULL) {
@@ -3220,12 +3342,10 @@ bool ED_space_image_color_sample(SpaceImage *sima, ARegion *ar, int mval[2], flo
     return false;
   }
 
-  UI_view2d_region_to_view(&ar->v2d, mval[0], mval[1], &fx, &fy);
-
-  if (fx >= 0.0f && fy >= 0.0f && fx < 1.0f && fy < 1.0f) {
+  if (uv[0] >= 0.0f && uv[1] >= 0.0f && uv[0] < 1.0f && uv[1] < 1.0f) {
     const float *fp;
     unsigned char *cp;
-    int x = (int)(fx * ibuf->x), y = (int)(fy * ibuf->y);
+    int x = (int)(uv[0] * ibuf->x), y = (int)(uv[1] * ibuf->y);
 
     CLAMP(x, 0, ibuf->x - 1);
     CLAMP(y, 0, ibuf->y - 1);
@@ -3326,10 +3446,15 @@ static void image_sample_apply(bContext *C, wmOperator *op, const wmEvent *event
 {
   SpaceImage *sima = CTX_wm_space_image(C);
   ARegion *ar = CTX_wm_region(C);
+  Image *image = ED_space_image(sima);
+
+  float uv[2];
+  UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &uv[0], &uv[1]);
+  int tile = BKE_image_get_tile_from_pos(sima->image, uv, uv, NULL);
+
   void *lock;
-  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock, tile);
   ImageSampleInfo *info = op->customdata;
-  float fx, fy;
   Scene *scene = CTX_data_scene(C);
   CurveMapping *curve_mapping = scene->view_settings.curve_mapping;
 
@@ -3339,11 +3464,8 @@ static void image_sample_apply(bContext *C, wmOperator *op, const wmEvent *event
     return;
   }
 
-  UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &fx, &fy);
-
-  if (fx >= 0.0f && fy >= 0.0f && fx < 1.0f && fy < 1.0f) {
-    int x = (int)(fx * ibuf->x), y = (int)(fy * ibuf->y);
-    Image *image = ED_space_image(sima);
+  if (uv[0] >= 0.0f && uv[1] >= 0.0f && uv[0] < 1.0f && uv[1] < 1.0f) {
+    int x = (int)(uv[0] * ibuf->x), y = (int)(uv[1] * ibuf->y);
 
     CLAMP(x, 0, ibuf->x - 1);
     CLAMP(y, 0, ibuf->y - 1);
@@ -3551,18 +3673,25 @@ static int image_sample_line_exec(bContext *C, wmOperator *op)
   SpaceImage *sima = CTX_wm_space_image(C);
   ARegion *ar = CTX_wm_region(C);
   Scene *scene = CTX_data_scene(C);
+  Image *ima = ED_space_image(sima);
 
   int x_start = RNA_int_get(op->ptr, "xstart");
   int y_start = RNA_int_get(op->ptr, "ystart");
   int x_end = RNA_int_get(op->ptr, "xend");
   int y_end = RNA_int_get(op->ptr, "yend");
 
+  float uv1[2], uv2[2], ofs[2];
+  UI_view2d_region_to_view(&ar->v2d, x_start, y_start, &uv1[0], &uv1[1]);
+  UI_view2d_region_to_view(&ar->v2d, x_end, y_end, &uv2[0], &uv2[1]);
+
+  /* If the image has tiles, shift the positions accordingly. */
+  int tile = BKE_image_get_tile_from_pos(ima, uv1, uv1, ofs);
+  sub_v2_v2(uv2, ofs);
+
   void *lock;
-  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock, tile);
   Histogram *hist = &sima->sample_line_hist;
 
-  float x1f, y1f, x2f, y2f;
-
   if (ibuf == NULL) {
     ED_space_image_release_buffer(sima, ibuf, lock);
     return OPERATOR_CANCELLED;
@@ -3573,13 +3702,8 @@ static int image_sample_line_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  UI_view2d_region_to_view(&ar->v2d, x_start, y_start, &x1f, &y1f);
-  UI_view2d_region_to_view(&ar->v2d, x_end, y_end, &x2f, &y2f);
-
-  hist->co[0][0] = x1f;
-  hist->co[0][1] = y1f;
-  hist->co[1][0] = x2f;
-  hist->co[1][1] = y2f;
+  copy_v2_v2(hist->co[0], uv1);
+  copy_v2_v2(hist->co[1], uv2);
 
   /* enable line drawing */
   hist->flag |= HISTO_FLAG_SAMPLELINE;
@@ -4085,3 +4209,248 @@ void IMAGE_OT_clear_render_border(wmOperatorType *ot)
 }
 
 /** \} */
+
+/* ********************* Add tile operator ****************** */
+
+static bool tile_poll(bContext *C)
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  return (ima != NULL && ima->source == IMA_SRC_TILED);
+}
+
+static int tile_add_exec(bContext *C, wmOperator *op)
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  int tile_number = RNA_int_get(op->ptr, "number");
+
+  char *label = RNA_string_get_alloc(op->ptr, "label", NULL, 0);
+
+  ImageTile *tile = BKE_image_add_tile(ima, tile_number, label);
+  MEM_freeN(label);
+
+  if (tile == NULL) {
+    return OPERATOR_CANCELLED;
+  }
+
+  ima->active_tile_index = BLI_findindex(&ima->tiles, tile);
+
+  WM_event_add_notifier(C, NC_IMAGE | ND_DRAW, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+static int tile_add_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(event))
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  /* Find the first gap in tile numbers or the number after the last if
+   * no gap exists. */
+  int next_number = 0;
+  LISTBASE_FOREACH (ImageTile *, tile, &ima->tiles) {
+    next_number = tile->tile_number + 1;
+    if (tile->next == NULL || tile->next->tile_number > next_number) {
+      break;
+    }
+  }
+
+  RNA_int_set(op->ptr, "number", next_number);
+  RNA_string_set(op->ptr, "label", "");
+
+  return WM_operator_props_dialog_popup(C, op, 5 * UI_UNIT_X, 5 * UI_UNIT_Y);
+}
+
+static void tile_add_draw(bContext *UNUSED(C), wmOperator *op)
+{
+  uiLayout *split, *col[2];
+  uiLayout *layout = op->layout;
+  PointerRNA ptr;
+
+  RNA_pointer_create(NULL, op->type->srna, op->properties, &ptr);
+
+  split = uiLayoutSplit(layout, 0.5f, false);
+  col[0] = uiLayoutColumn(split, false);
+  col[1] = uiLayoutColumn(split, false);
+
+  uiItemL(col[0], IFACE_("Number"), ICON_NONE);
+  uiItemR(col[1], &ptr, "number", 0, "", ICON_NONE);
+
+  uiItemL(col[0], IFACE_("Label"), ICON_NONE);
+  uiItemR(col[1], &ptr, "label", 0, "", ICON_NONE);
+}
+
+void IMAGE_OT_tile_add(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Add tile";
+  ot->description = "Adds a tile to the image";
+  ot->idname = "IMAGE_OT_tile_add";
+
+  /* api callbacks */
+  ot->poll = tile_poll;
+  ot->exec = tile_add_exec;
+  ot->invoke = tile_add_invoke;
+  ot->ui = tile_add_draw;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  RNA_def_int(
+      ot->srna, "number", 1002, 1001, INT_MAX, "Number", "UDIM number of the tile", 1001, 1099);
+  RNA_def_string(ot->srna, "label", NULL, 0, "Label", "Optional tile label");
+}
+
+/* ********************* Remove tile operator ****************** */
+
+static bool tile_remove_poll(bContext *C)
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  return (ima != NULL && ima->source == IMA_SRC_TILED && ima->active_tile_index != 0);
+}
+
+static int tile_remove_exec(bContext *C, wmOperator *UNUSED(op))
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  ImageTile *tile = BLI_findlink(&ima->tiles, ima->active_tile_index);
+  if (!BKE_image_remove_tile(ima, tile)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  /* Ensure that the active index is valid. */
+  ima->active_tile_index = min_ii(ima->active_tile_index, BLI_listbase_count(&ima->tiles) - 1);
+
+  WM_event_add_notifier(C, NC_IMAGE | ND_DRAW, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void IMAGE_OT_tile_remove(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Remove tile";
+  ot->description = "Removes a tile from the image";
+  ot->idname = "IMAGE_OT_tile_remove";
+
+  /* api callbacks */
+  ot->poll = tile_remove_poll;
+  ot->exec = tile_remove_exec;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}
+
+/* ********************* Fill tile operator ****************** */
+
+static int tile_fill_exec(bContext *C, wmOperator *op)
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  float color[4];
+  RNA_float_get_array(op->ptr, "color", color);
+  int gen_type = RNA_enum_get(op->ptr, "generated_type");
+  int width = RNA_int_get(op->ptr, "width");
+  int height = RNA_int_get(op->ptr, "height");
+  bool is_float = RNA_boolean_get(op->ptr, "float");
+  int planes = RNA_boolean_get(op->ptr, "alpha") ? 32 : 24;
+
+  ImageTile *tile = BLI_findlink(&ima->tiles, ima->active_tile_index);
+  if (!BKE_image_fill_tile(ima, tile, width, height, color, gen_type, planes, is_float)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  WM_event_add_notifier(C, NC_IMAGE | ND_DRAW, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+static int tile_fill_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(event))
+{
+  Image *ima = CTX_data_edit_image(C);
+
+  /* Acquire first tile to get the defaults. */
+  ImBuf *ibuf = BKE_image_acquire_ibuf(ima, NULL, NULL);
+  if (ibuf != NULL) {
+    RNA_int_set(op->ptr, "width", ibuf->x);
+    RNA_int_set(op->ptr, "height", ibuf->y);
+    RNA_boolean_set(op->ptr, "float", ibuf->rect_float != NULL);
+    RNA_boolean_set(op->ptr, "alpha", ibuf->planes > 24);
+    BKE_image_release_ibuf(ima, ibuf, NULL);
+  }
+
+  return WM_operator_props_dialog_popup(C, op, 15 * UI_UNIT_X, 5 * UI_UNIT_Y);
+}
+
+static void tile_fill_draw(bContext *UNUSED(C), wmOperator *op)
+{
+  uiLayout *split, *col[2];
+  uiLayout *layout = op->layout;
+  PointerRNA ptr;
+
+  RNA_pointer_create(NULL, op->type->srna, op->properties, &ptr);
+
+  /* copy of WM_operator_props_dialog_popup() layout */
+
+  split = uiLayoutSplit(layout, 0.5f, false);
+  col[0] = uiLayoutColumn(split, false);
+  col[1] = uiLayoutColumn(split, false);
+
+  uiItemL(col[0], IFACE_("Color"), ICON_NONE);
+  uiItemR(col[1], &ptr, "color", 0, "", ICON_NONE);
+
+  uiItemL(col[0], IFACE_("Width"), ICON_NONE);
+  uiItemR(col[1], &ptr, "width", 0, "", ICON_NONE);
+
+  uiItemL(col[0], IFACE_("Height"), ICON_NONE);
+  uiItemR(col[1], &ptr, "height", 0, "", ICON_NONE);
+
+  uiItemL(col[0], "", ICON_NONE);
+  uiItemR(col[1], &ptr, "alpha", 0, NULL, ICON_NONE);
+
+  uiItemL(col[0], IFACE_("Generated Type"), ICON_NONE);
+  uiItemR(col[1], &ptr, "generated_type", 0, "", ICON_NONE);
+
+  uiItemL(col[0], "", ICON_NONE);
+  uiItemR(col[1], &ptr, "float", 0, NULL, ICON_NONE);
+}
+
+void IMAGE_OT_tile_fill(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Fill tile";
+  ot->description = "Fill the current tile with a generated image";
+  ot->idname = "IMAGE_OT_tile_fill";
+
+  /* api callbacks */
+  ot->poll = tile_poll;
+  ot->exec = tile_fill_exec;
+  ot->invoke = tile_fill_invoke;
+  ot->ui = tile_fill_draw;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  PropertyRNA *prop;
+  static float default_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+  prop = RNA_def_float_color(
+      ot->srna, "color", 4, NULL, 0.0f, FLT_MAX, "Color", "Default fill color", 0.0f, 1.0f);
+  RNA_def_property_subtype(prop, PROP_COLOR_GAMMA);
+  RNA_def_property_float_array_default(prop, default_color);
+  RNA_def_enum(ot->srna,
+               "generated_type",
+               rna_enum_image_generated_type_items,
+               IMA_GENTYPE_BLANK,
+               "Generated Type",
+               "Fill the image with a grid for UV map testing");
+  prop = RNA_def_int(ot->srna, "width", 1024, 1, INT_MAX, "Width", "Image width", 1, 16384);
+  RNA_def_property_subtype(prop, PROP_PIXEL);
+  prop = RNA_def_int(ot->srna, "height", 1024, 1, INT_MAX, "Height", "Image height", 1, 16384);
+  RNA_def_property_subtype(prop, PROP_PIXEL);
+
+  /* Only needed when filling the first tile. */
+  RNA_def_boolean(
+      ot->srna, "float", 0, "32 bit Float", "Create image with 32 bit floating point bit depth");
+  RNA_def_boolean(ot->srna, "alpha", 1, "Alpha", "Create an image with an alpha channel");
+}
diff --git a/source/blender/editors/space_image/image_undo.c b/source/blender/editors/space_image/image_undo.c
index b6b32293cee..79aa4d2ed7f 100644
--- a/source/blender/editors/space_image/image_undo.c
+++ b/source/blender/editors/space_image/image_undo.c
@@ -107,6 +107,7 @@ typedef struct PaintTile {
   struct PaintTile *next, *prev;
   Image *image;
   ImBuf *ibuf;
+  int tile_number;
   union {
     float *fp;
     uint *uint;
@@ -148,6 +149,7 @@ static void ptile_invalidate_list(ListBase *paint_tiles)
 void *ED_image_paint_tile_find(ListBase *paint_tiles,
                                Image *image,
                                ImBuf *ibuf,
+                               int tile_number,
                                int x_tile,
                                int y_tile,
                                ushort **r_mask,
@@ -155,7 +157,7 @@ void *ED_image_paint_tile_find(ListBase *paint_tiles,
 {
   for (PaintTile *ptile = paint_tiles->first; ptile; ptile = ptile->next) {
     if (ptile->x_tile == x_tile && ptile->y_tile == y_tile) {
-      if (ptile->image == image && ptile->ibuf == ibuf) {
+      if (ptile->image == image && ptile->ibuf == ibuf && ptile->tile_number == tile_number) {
         if (r_mask) {
           /* allocate mask if requested. */
           if (!ptile->mask) {
@@ -178,6 +180,7 @@ void *ED_image_paint_tile_push(ListBase *paint_tiles,
                                Image *image,
                                ImBuf *ibuf,
                                ImBuf **tmpibuf,
+                               int tile_number,
                                int x_tile,
                                int y_tile,
                                ushort **r_mask,
@@ -191,7 +194,8 @@ void *ED_image_paint_tile_push(ListBase *paint_tiles,
 
   /* in projective painting we keep accounting of tiles, so if we need one pushed, just push! */
   if (find_prev) {
-    void *data = ED_image_paint_tile_find(paint_tiles, image, ibuf, x_tile, y_tile, r_mask, true);
+    void *data = ED_image_paint_tile_find(
+        paint_tiles, image, ibuf, tile_number, x_tile, y_tile, r_mask, true);
     if (data) {
       return data;
     }
@@ -205,6 +209,7 @@ void *ED_image_paint_tile_push(ListBase *paint_tiles,
 
   ptile->image = image;
   ptile->ibuf = ibuf;
+  ptile->tile_number = tile_number;
 
   ptile->x_tile = x_tile;
   ptile->y_tile = y_tile;
@@ -259,7 +264,10 @@ static void ptile_restore_runtime_list(ListBase *paint_tiles)
 
   for (PaintTile *ptile = paint_tiles->first; ptile; ptile = ptile->next) {
     Image *image = ptile->image;
-    ImBuf *ibuf = BKE_image_acquire_ibuf(image, NULL, NULL);
+    ImageUser iuser;
+    BKE_imageuser_default(&iuser);
+    iuser.tile = ptile->tile_number;
+    ImBuf *ibuf = BKE_image_acquire_ibuf(image, &iuser, NULL);
     const bool has_float = (ibuf->rect_float != NULL);
 
     if (has_float) {
@@ -460,6 +468,8 @@ static void ubuf_from_image_all_tiles(UndoImageBuf *ubuf, const ImBuf *ibuf)
     }
   }
 
+  BLI_assert(i == ubuf->tiles_len);
+
   IMB_freeImBuf(tmpibuf);
 }
 
@@ -514,13 +524,13 @@ typedef struct UndoImageHandle {
   /** Each undo handle refers to a single image which may have multiple buffers. */
   UndoRefID_Image image_ref;
 
+  /** Each tile of a tiled image has its own UndoImageHandle.
+   * The tile number of this IUser is used to distinguish them.
+   */
+  ImageUser iuser;
+
   /**
    * List of #UndoImageBuf's to support multiple buffers per image.
-   *
-   * \note To properly support multiple buffers per image
-   * we would need to store an #ImageUser for each #UndoImageBuf.
-   * since when restoring the image we use:
-   * `BKE_image_acquire_ibuf(image, NULL, NULL)`.
    */
   ListBase buffers;
 
@@ -533,7 +543,8 @@ static void uhandle_restore_list(ListBase *undo_handles, bool use_init)
   for (UndoImageHandle *uh = undo_handles->first; uh; uh = uh->next) {
     /* Tiles only added to second set of tiles. */
     Image *image = uh->image_ref.ptr;
-    ImBuf *ibuf = BKE_image_acquire_ibuf(image, NULL, NULL);
+
+    ImBuf *ibuf = BKE_image_acquire_ibuf(image, &uh->iuser, NULL);
     if (UNLIKELY(ibuf == NULL)) {
       CLOG_ERROR(&LOG, "Unable to get buffer for image '%s'", image->id.name + 2);
       continue;
@@ -626,40 +637,44 @@ static UndoImageBuf *uhandle_ensure_ubuf(UndoImageHandle *uh, Image *image, ImBu
   return ubuf;
 }
 
-static UndoImageHandle *uhandle_lookup_by_name(ListBase *undo_handles, const Image *image)
+static UndoImageHandle *uhandle_lookup_by_name(ListBase *undo_handles,
+                                               const Image *image,
+                                               int tile_number)
 {
   for (UndoImageHandle *uh = undo_handles->first; uh; uh = uh->next) {
-    if (STREQ(image->id.name + 2, uh->image_ref.name + 2)) {
+    if (STREQ(image->id.name + 2, uh->image_ref.name + 2) && uh->iuser.tile == tile_number) {
       return uh;
     }
   }
   return NULL;
 }
 
-static UndoImageHandle *uhandle_lookup(ListBase *undo_handles, const Image *image)
+static UndoImageHandle *uhandle_lookup(ListBase *undo_handles, const Image *image, int tile_number)
 {
   for (UndoImageHandle *uh = undo_handles->first; uh; uh = uh->next) {
-    if (image == uh->image_ref.ptr) {
+    if (image == uh->image_ref.ptr && uh->iuser.tile == tile_number) {
       return uh;
     }
   }
   return NULL;
 }
 
-static UndoImageHandle *uhandle_add(ListBase *undo_handles, Image *image)
+static UndoImageHandle *uhandle_add(ListBase *undo_handles, Image *image, int tile_number)
 {
-  BLI_assert(uhandle_lookup(undo_handles, image) == NULL);
+  BLI_assert(uhandle_lookup(undo_handles, image, tile_number) == NULL);
   UndoImageHandle *uh = MEM_callocN(sizeof(*uh), __func__);
   uh->image_ref.ptr = image;
+  uh->iuser.ok = 1;
+  uh->iuser.tile = tile_number;
   BLI_addtail(undo_handles, uh);
   return uh;
 }
 
-static UndoImageHandle *uhandle_ensure(ListBase *undo_handles, Image *image)
+static UndoImageHandle *uhandle_ensure(ListBase *undo_handles, Image *image, int tile_number)
 {
-  UndoImageHandle *uh = uhandle_lookup(undo_handles, image);
+  UndoImageHandle *uh = uhandle_lookup(undo_handles, image, tile_number);
   if (uh == NULL) {
-    uh = uhandle_add(undo_handles, image);
+    uh = uhandle_add(undo_handles, image, tile_number);
   }
   return uh;
 }
@@ -693,10 +708,11 @@ typedef struct ImageUndoStep {
  */
 static UndoImageBuf *ubuf_lookup_from_reference(ImageUndoStep *us_prev,
                                                 const Image *image,
+                                                int tile_number,
                                                 const UndoImageBuf *ubuf)
 {
   /* Use name lookup because because the pointer is cleared for previous steps. */
-  UndoImageHandle *uh_prev = uhandle_lookup_by_name(&us_prev->handles, image);
+  UndoImageHandle *uh_prev = uhandle_lookup_by_name(&us_prev->handles, image, tile_number);
   if (uh_prev != NULL) {
     UndoImageBuf *ubuf_reference = uhandle_lookup_ubuf(uh_prev, image, ubuf->ibuf_name);
     if (ubuf_reference) {
@@ -763,7 +779,7 @@ static bool image_undosys_step_encode(struct bContext *C,
     /* Initialize undo tiles from ptiles (if they exist). */
     for (PaintTile *ptile = us->paint_tiles.first, *ptile_next; ptile; ptile = ptile_next) {
       if (ptile->valid) {
-        UndoImageHandle *uh = uhandle_ensure(&us->handles, ptile->image);
+        UndoImageHandle *uh = uhandle_ensure(&us->handles, ptile->image, ptile->tile_number);
         UndoImageBuf *ubuf_pre = uhandle_ensure_ubuf(uh, ptile->image, ptile->ibuf);
 
         UndoImageTile *utile = MEM_callocN(sizeof(*utile), "UndoImageTile");
@@ -783,7 +799,7 @@ static bool image_undosys_step_encode(struct bContext *C,
     for (UndoImageHandle *uh = us->handles.first; uh; uh = uh->next) {
       for (UndoImageBuf *ubuf_pre = uh->buffers.first; ubuf_pre; ubuf_pre = ubuf_pre->next) {
 
-        ImBuf *ibuf = BKE_image_acquire_ibuf(uh->image_ref.ptr, NULL, NULL);
+        ImBuf *ibuf = BKE_image_acquire_ibuf(uh->image_ref.ptr, &uh->iuser, NULL);
 
         const bool has_float = ibuf->rect_float;
 
@@ -797,10 +813,10 @@ static bool image_undosys_step_encode(struct bContext *C,
         }
         else {
           /* Search for the previous buffer. */
-          UndoImageBuf *ubuf_reference = (us_reference ?
-                                              ubuf_lookup_from_reference(
-                                                  us_reference, uh->image_ref.ptr, ubuf_post) :
-                                              NULL);
+          UndoImageBuf *ubuf_reference =
+              (us_reference ? ubuf_lookup_from_reference(
+                                  us_reference, uh->image_ref.ptr, uh->iuser.tile, ubuf_post) :
+                              NULL);
 
           int i = 0;
           for (uint y_tile = 0; y_tile < ubuf_pre->tiles_dims[1]; y_tile += 1) {
@@ -850,6 +866,8 @@ static bool image_undosys_step_encode(struct bContext *C,
               i += 1;
             }
           }
+          BLI_assert(i == ubuf_pre->tiles_len);
+          BLI_assert(i == ubuf_post->tiles_len);
         }
         BKE_image_release_ibuf(uh->image_ref.ptr, ibuf, NULL);
       }
@@ -1026,11 +1044,15 @@ void ED_image_undo_push_begin(const char *name, int paint_mode)
   image_undo_push_begin(name, paint_mode);
 }
 
-void ED_image_undo_push_begin_with_image(const char *name, Image *image, ImBuf *ibuf)
+void ED_image_undo_push_begin_with_image(const char *name,
+                                         Image *image,
+                                         ImBuf *ibuf,
+                                         int tile_number)
 {
   ImageUndoStep *us = image_undo_push_begin(name, PAINT_MODE_TEXTURE_2D);
 
-  UndoImageHandle *uh = uhandle_ensure(&us->handles, image);
+  BLI_assert(BKE_image_get_tile(image, tile_number));
+  UndoImageHandle *uh = uhandle_ensure(&us->handles, image, tile_number);
   UndoImageBuf *ubuf_pre = uhandle_ensure_ubuf(uh, image, ibuf);
   BLI_assert(ubuf_pre->post == NULL);
 
@@ -1038,9 +1060,9 @@ void ED_image_undo_push_begin_with_image(const char *name, Image *image, ImBuf *
   while (us_reference && us_reference->step.type != BKE_UNDOSYS_TYPE_IMAGE) {
     us_reference = (ImageUndoStep *)us_reference->step.prev;
   }
-  UndoImageBuf *ubuf_reference = (us_reference ?
-                                      ubuf_lookup_from_reference(us_reference, image, ubuf_pre) :
-                                      NULL);
+  UndoImageBuf *ubuf_reference = (us_reference ? ubuf_lookup_from_reference(
+                                                     us_reference, image, tile_number, ubuf_pre) :
+                                                 NULL);
 
   if (ubuf_reference) {
     memcpy(ubuf_pre->tiles, ubuf_reference->tiles, sizeof(*ubuf_pre->tiles) * ubuf_pre->tiles_len);
diff --git a/source/blender/editors/space_image/space_image.c b/source/blender/editors/space_image/space_image.c
index a88ecc91868..f30c0e97cab 100644
--- a/source/blender/editors/space_image/space_image.c
+++ b/source/blender/editors/space_image/space_image.c
@@ -134,6 +134,9 @@ static SpaceLink *image_new(const ScrArea *UNUSED(area), const Scene *UNUSED(sce
   BKE_scopes_new(&simage->scopes);
   simage->sample_line_hist.height = 100;
 
+  simage->tile_grid_shape[0] = 1;
+  simage->tile_grid_shape[1] = 1;
+
   /* tool header */
   ar = MEM_callocN(sizeof(ARegion), "tool header for image");
 
@@ -246,6 +249,10 @@ static void image_operatortypes(void)
   WM_operatortype_append(IMAGE_OT_read_viewlayers);
   WM_operatortype_append(IMAGE_OT_render_border);
   WM_operatortype_append(IMAGE_OT_clear_render_border);
+
+  WM_operatortype_append(IMAGE_OT_tile_add);
+  WM_operatortype_append(IMAGE_OT_tile_remove);
+  WM_operatortype_append(IMAGE_OT_tile_fill);
 }
 
 static void image_keymap(struct wmKeyConfig *keyconf)
@@ -783,7 +790,8 @@ static void image_buttons_region_draw(const bContext *C, ARegion *ar)
   SpaceImage *sima = CTX_wm_space_image(C);
   Scene *scene = CTX_data_scene(C);
   void *lock;
-  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock);
+  /* TODO(lukas): Support tiles in scopes? */
+  ImBuf *ibuf = ED_space_image_acquire_buffer(sima, &lock, 0);
   /* XXX performance regression if name of scopes category changes! */
   PanelCategoryStack *category = UI_panel_category_active_find(ar, "Scopes");