Cycles/Eevee: unified and improved texture image color space handling

Cycles now uses the color space on the image datablock, and uses OpenColorIO
to convert to scene linear as needed. Byte images do not take extra memory,
they are compressed in scene linear + sRGB transfer function which in common
cases is a no-op.

Eevee and workbench were changed to work similar. Float images are stored as
scene linear. Byte images are compressed as scene linear + sRGB and stored in
a GL_SRGB8_ALPHA8 texture. From the GLSL shader side this means they are read
as scene linear, simplifying the code and taking advantage of hardware support.

Further, OpenGL image textures are now all stored with premultiplied alpha.
Eevee texture sampling looks a little different now because interpolation
happens premultiplied and in scene linear space.

Overlays and grease pencil work in sRGB space so those now have an extra
conversion to sRGB after reading from image textures. This is not particularly
elegant but as long as engines use different conventions, one or the other
needs to do conversion.

This change breaks compatibility for cases where multiple image texture nodes
were using the same image with different color space node settings. However it
gives more predictable behavior for baking and texture painting if save, load
and image editing operations have a single color space to handle.

Differential Revision: https://developer.blender.org/D4807

9 files changed, 256 insertions, 290 deletions

diff --git a/source/blender/gpu/GPU_draw.h b/source/blender/gpu/GPU_draw.h
index 300fc7c65a2..eb54ff127d8 100644
--- a/source/blender/gpu/GPU_draw.h
+++ b/source/blender/gpu/GPU_draw.h
@@ -84,7 +84,7 @@ void GPU_create_gl_tex(unsigned int *bind,
                        int recth,
                        int textarget,
                        bool mipmap,
-                       bool use_hight_bit_depth,
+                       bool use_srgb,
                        struct Image *ima);
 void GPU_create_gl_tex_compressed(unsigned int *bind,
                                   unsigned int *pix,
diff --git a/source/blender/gpu/GPU_material.h b/source/blender/gpu/GPU_material.h
index 1640209c717..86c9764a68f 100644
--- a/source/blender/gpu/GPU_material.h
+++ b/source/blender/gpu/GPU_material.h
@@ -145,7 +145,7 @@ typedef enum eGPUMaterialStatus {
 GPUNodeLink *GPU_attribute(CustomDataType type, const char *name);
 GPUNodeLink *GPU_constant(float *num);
 GPUNodeLink *GPU_uniform(float *num);
-GPUNodeLink *GPU_image(struct Image *ima, struct ImageUser *iuser, bool is_data);
+GPUNodeLink *GPU_image(struct Image *ima, struct ImageUser *iuser);
 GPUNodeLink *GPU_color_band(GPUMaterial *mat, int size, float *pixels, float *layer);
 GPUNodeLink *GPU_builtin(eGPUBuiltin builtin);
 
@@ -202,7 +202,6 @@ struct GPUUniformBuffer *GPU_material_create_sss_profile_ubo(void);
 
 void GPU_material_vertex_attrs(GPUMaterial *material, struct GPUVertAttrLayers *attrs);
 
-bool GPU_material_do_color_management(GPUMaterial *mat);
 bool GPU_material_use_domain_surface(GPUMaterial *mat);
 bool GPU_material_use_domain_volume(GPUMaterial *mat);
 
diff --git a/source/blender/gpu/GPU_texture.h b/source/blender/gpu/GPU_texture.h
index 3527398a396..3fb7dfc6331 100644
--- a/source/blender/gpu/GPU_texture.h
+++ b/source/blender/gpu/GPU_texture.h
@@ -186,10 +186,7 @@ GPUTexture *GPU_texture_create_from_vertbuf(struct GPUVertBuf *vert);
 GPUTexture *GPU_texture_create_buffer(eGPUTextureFormat data_type, const uint buffer);
 
 GPUTexture *GPU_texture_from_bindcode(int textarget, int bindcode);
-GPUTexture *GPU_texture_from_blender(struct Image *ima,
-                                     struct ImageUser *iuser,
-                                     int textarget,
-                                     bool is_data);
+GPUTexture *GPU_texture_from_blender(struct Image *ima, struct ImageUser *iuser, int textarget);
 GPUTexture *GPU_texture_from_preview(struct PreviewImage *prv, int mipmap);
 
 void GPU_texture_add_mipmap(GPUTexture *tex,
diff --git a/source/blender/gpu/intern/gpu_codegen.c b/source/blender/gpu/intern/gpu_codegen.c
index a2c1a01a82c..6259780c261 100644
--- a/source/blender/gpu/intern/gpu_codegen.c
+++ b/source/blender/gpu/intern/gpu_codegen.c
@@ -1503,7 +1503,6 @@ static void gpu_node_input_link(GPUNode *node, GPUNodeLink *link, const eGPUType
       input->source = GPU_SOURCE_TEX;
       input->ima = link->ima;
       input->iuser = link->iuser;
-      input->image_isdata = link->image_isdata;
       break;
     case GPU_NODE_LINK_ATTR:
       input->source = GPU_SOURCE_ATTR;
@@ -1748,13 +1747,12 @@ GPUNodeLink *GPU_uniform(float *num)
   return link;
 }
 
-GPUNodeLink *GPU_image(Image *ima, ImageUser *iuser, bool is_data)
+GPUNodeLink *GPU_image(Image *ima, ImageUser *iuser)
 {
   GPUNodeLink *link = GPU_node_link_create();
   link->link_type = GPU_NODE_LINK_IMAGE_BLENDER;
   link->ima = ima;
   link->iuser = iuser;
-  link->image_isdata = is_data;
   return link;
 }
 
diff --git a/source/blender/gpu/intern/gpu_codegen.h b/source/blender/gpu/intern/gpu_codegen.h
index 73155c3aafa..d1bb3f26920 100644
--- a/source/blender/gpu/intern/gpu_codegen.h
+++ b/source/blender/gpu/intern/gpu_codegen.h
@@ -99,7 +99,6 @@ struct GPUNodeLink {
     struct {
       struct Image *ima;
       struct ImageUser *iuser;
-      bool image_isdata;
     };
   };
 };
@@ -137,7 +136,6 @@ typedef struct GPUInput {
       struct GPUTexture **coba; /* input texture, only set at runtime */
       struct Image *ima;        /* image */
       struct ImageUser *iuser;  /* image user */
-      bool image_isdata;        /* image does not contain color data */
       bool bindtex;             /* input is responsible for binding the texture? */
       int texid;                /* number for multitexture, starting from zero */
       eGPUType textype;         /* texture type (2D, 1D Array ...) */
diff --git a/source/blender/gpu/intern/gpu_draw.c b/source/blender/gpu/intern/gpu_draw.c
index edc2f2171a5..f1c82dc53a7 100644
--- a/source/blender/gpu/intern/gpu_draw.c
+++ b/source/blender/gpu/intern/gpu_draw.c
@@ -50,6 +50,7 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "IMB_colormanagement.h"
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
@@ -207,53 +208,232 @@ static GPUTexture **gpu_get_image_gputexture(Image *ima, GLenum textarget)
   return NULL;
 }
 
-typedef struct VerifyThreadData {
-  ImBuf *ibuf;
-  float *srgb_frect;
-} VerifyThreadData;
+static uint gpu_texture_create_from_ibuf(Image *ima, ImBuf *ibuf, int textarget)
+{
+  uint bindcode = 0;
+  const bool mipmap = GPU_get_mipmap();
+
+#ifdef WITH_DDS
+  if (ibuf->ftype == IMB_FTYPE_DDS) {
+    /* DDS is loaded directly in compressed form. */
+    GPU_create_gl_tex_compressed(
+        &bindcode, ibuf->rect, ibuf->x, ibuf->y, textarget, mipmap, ima, ibuf);
+    return bindcode;
+  }
+#endif
+
+  /* Regular uncompressed texture. */
+  float *rect_float = ibuf->rect_float;
+  uchar *rect = (uchar *)ibuf->rect;
+  bool compress_as_srgb = false;
+
+  if (rect_float == NULL) {
+    /* Byte image is in original colorspace from the file. If the file is sRGB
+     * scene linear, or non-color data no conversion is needed. Otherwise we
+     * compress as scene linear + sRGB transfer function to avoid precision loss
+     * in common cases.
+     *
+     * We must also convert to premultiplied for correct texture interpolation
+     * and consistency with float images. */
+    if (!IMB_colormanagement_space_is_data(ibuf->rect_colorspace)) {
+      compress_as_srgb = !IMB_colormanagement_space_is_scene_linear(ibuf->rect_colorspace);
+
+      rect = MEM_mallocN(sizeof(uchar) * 4 * ibuf->x * ibuf->y, __func__);
+      if (rect == NULL) {
+        return bindcode;
+      }
+
+      IMB_colormanagement_imbuf_to_srgb_texture(
+          rect, 0, 0, ibuf->x, ibuf->y, ibuf, compress_as_srgb);
+    }
+  }
+  else if (ibuf->channels != 4) {
+    /* Float image is already in scene linear colorspace or non-color data by
+     * convention, no colorspace conversion needed. But we do require 4 channels
+     * currently. */
+    rect_float = MEM_mallocN(sizeof(float) * 4 * ibuf->x * ibuf->y, __func__);
+    if (rect_float == NULL) {
+      return bindcode;
+    }
 
-static void gpu_verify_high_bit_srgb_buffer_slice(float *srgb_frect,
-                                                  ImBuf *ibuf,
-                                                  const int start_line,
-                                                  const int height)
+    IMB_buffer_float_from_float(rect_float,
+                                ibuf->rect_float,
+                                ibuf->channels,
+                                IB_PROFILE_LINEAR_RGB,
+                                IB_PROFILE_LINEAR_RGB,
+                                false,
+                                ibuf->x,
+                                ibuf->y,
+                                ibuf->x,
+                                ibuf->x);
+  }
+
+  /* Create OpenGL texture. */
+  GPU_create_gl_tex(&bindcode,
+                    (uint *)rect,
+                    rect_float,
+                    ibuf->x,
+                    ibuf->y,
+                    textarget,
+                    mipmap,
+                    compress_as_srgb,
+                    ima);
+
+  /* Free buffers if needed. */
+  if (rect && rect != (uchar *)ibuf->rect) {
+    MEM_freeN(rect);
+  }
+  if (rect_float && rect_float != ibuf->rect_float) {
+    MEM_freeN(rect_float);
+  }
+
+  return bindcode;
+}
+
+static void gpu_texture_update_scaled(
+    uchar *rect, float *rect_float, int full_w, int full_h, int x, int y, int w, int h)
 {
-  size_t offset = ibuf->channels * start_line * ibuf->x;
-  float *current_srgb_frect = srgb_frect + offset;
-  float *current_rect_float = ibuf->rect_float + offset;
-  IMB_buffer_float_from_float(current_srgb_frect,
-                              current_rect_float,
-                              ibuf->channels,
-                              IB_PROFILE_SRGB,
-                              IB_PROFILE_LINEAR_RGB,
-                              true,
-                              ibuf->x,
-                              height,
-                              ibuf->x,
-                              ibuf->x);
-  IMB_buffer_float_unpremultiply(current_srgb_frect, ibuf->x, height);
+  /* Partial update with scaling. */
+  int limit_w = smaller_power_of_2_limit(full_w);
+  int limit_h = smaller_power_of_2_limit(full_h);
+  float xratio = limit_w / (float)full_w;
+  float yratio = limit_h / (float)full_h;
+
+  /* Find sub coordinates in scaled image. Take ceiling because we will be
+   * losing 1 pixel due to rounding errors in x,y. */
+  int sub_x = x * xratio;
+  int sub_y = y * yratio;
+  int sub_w = (int)ceil(xratio * w);
+  int sub_h = (int)ceil(yratio * h);
+
+  /* ...but take back if we are over the limit! */
+  if (sub_w + sub_x > limit_w) {
+    sub_w--;
+  }
+  if (sub_h + sub_y > limit_h) {
+    sub_h--;
+  }
+
+  /* Scale pixels. */
+  ImBuf *ibuf = IMB_allocFromBuffer((uint *)rect, rect_float, w, h);
+  IMB_scaleImBuf(ibuf, sub_w, sub_h);
+
+  if (ibuf->rect_float) {
+    glTexSubImage2D(
+        GL_TEXTURE_2D, 0, sub_x, sub_y, sub_w, sub_h, GL_RGBA, GL_FLOAT, ibuf->rect_float);
+  }
+  else {
+    glTexSubImage2D(
+        GL_TEXTURE_2D, 0, sub_x, sub_y, sub_w, sub_h, GL_RGBA, GL_UNSIGNED_BYTE, ibuf->rect);
+  }
+
+  IMB_freeImBuf(ibuf);
 }
 
-static void verify_thread_do(void *data_v, int start_scanline, int num_scanlines)
+static void gpu_texture_update_unscaled(
+    uchar *rect, float *rect_float, int x, int y, int w, int h, GLint tex_stride, GLint tex_offset)
 {
-  VerifyThreadData *data = (VerifyThreadData *)data_v;
-  gpu_verify_high_bit_srgb_buffer_slice(
-      data->srgb_frect, data->ibuf, start_scanline, num_scanlines);
+  /* Partial update without scaling. Stride and offset are used to copy only a
+   * subset of a possible larger buffer than what we are updating. */
+  GLint row_length;
+  glGetIntegerv(GL_UNPACK_ROW_LENGTH, &row_length);
+  glPixelStorei(GL_UNPACK_ROW_LENGTH, tex_stride);
+
+  if (rect_float == NULL) {
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_UNSIGNED_BYTE, rect + tex_offset);
+  }
+  else {
+    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_FLOAT, rect_float + tex_offset);
+  }
+
+  glPixelStorei(GL_UNPACK_ROW_LENGTH, row_length);
 }
 
-static void gpu_verify_high_bit_srgb_buffer(float *srgb_frect, ImBuf *ibuf)
+static void gpu_texture_update_from_ibuf(ImBuf *ibuf, int x, int y, int w, int h)
 {
-  if (ibuf->y < 64) {
-    gpu_verify_high_bit_srgb_buffer_slice(srgb_frect, ibuf, 0, ibuf->y);
+  /* Partial update of texture for texture painting. This is often much
+   * quicker than fully updating the texture for high resolution images.
+   * Assumes the OpenGL texture is bound to 0. */
+  const bool scaled = is_over_resolution_limit(GL_TEXTURE_2D, ibuf->x, ibuf->y);
+
+  if (scaled) {
+    /* Extra padding to account for bleed from neighboring pixels. */
+    const int padding = 4;
+    const int xmax = min_ii(x + w + padding, ibuf->x);
+    const int ymax = min_ii(y + h + padding, ibuf->y);
+    x = max_ii(x - padding, 0);
+    y = max_ii(y - padding, 0);
+    w = xmax - x;
+    h = ymax - y;
+  }
+
+  /* Get texture data pointers. */
+  float *rect_float = ibuf->rect_float;
+  uchar *rect = (uchar *)ibuf->rect;
+  GLint tex_stride = ibuf->x;
+  GLint tex_offset = ibuf->channels * (y * ibuf->x + x);
+
+  if (rect_float == NULL) {
+    /* Byte pixels. */
+    if (!IMB_colormanagement_space_is_data(ibuf->rect_colorspace)) {
+      const bool compress_as_srgb = !IMB_colormanagement_space_is_scene_linear(
+          ibuf->rect_colorspace);
+
+      rect = MEM_mallocN(sizeof(uchar) * 4 * w * h, __func__);
+      if (rect == NULL) {
+        return;
+      }
+
+      tex_stride = w;
+      tex_offset = 0;
+
+      /* Convert to scene linear with sRGB compression, and premultiplied for
+       * correct texture interpolation. */
+      IMB_colormanagement_imbuf_to_srgb_texture(rect, x, y, w, h, ibuf, compress_as_srgb);
+    }
+  }
+  else if (ibuf->channels != 4 || scaled) {
+    /* Float pixels. */
+    rect_float = MEM_mallocN(sizeof(float) * 4 * x * y, __func__);
+    if (rect_float == NULL) {
+      return;
+    }
+
+    tex_stride = w;
+    tex_offset = 0;
+
+    size_t ibuf_offset = (y * ibuf->x + x) * ibuf->channels;
+    IMB_buffer_float_from_float(rect_float,
+                                ibuf->rect_float + ibuf_offset,
+                                ibuf->channels,
+                                IB_PROFILE_LINEAR_RGB,
+                                IB_PROFILE_LINEAR_RGB,
+                                false,
+                                w,
+                                h,
+                                x,
+                                ibuf->x);
+  }
+
+  if (scaled) {
+    /* Slower update where we first have to scale the input pixels. */
+    gpu_texture_update_scaled(rect, rect_float, ibuf->x, ibuf->y, x, y, w, h);
   }
   else {
-    VerifyThreadData data;
-    data.ibuf = ibuf;
-    data.srgb_frect = srgb_frect;
-    IMB_processor_apply_threaded_scanlines(ibuf->y, verify_thread_do, &data);
+    /* Fast update at same resolution. */
+    gpu_texture_update_unscaled(rect, rect_float, x, y, w, h, tex_stride, tex_offset);
+  }
+
+  /* Free buffers if needed. */
+  if (rect && rect != (uchar *)ibuf->rect) {
+    MEM_freeN(rect);
+  }
+  if (rect_float && rect_float != ibuf->rect_float) {
+    MEM_freeN(rect_float);
   }
 }
 
-GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int textarget, bool is_data)
+GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int textarget)
 {
   if (ima == NULL) {
     return NULL;
@@ -286,62 +466,7 @@ GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int textarget
     return *tex;
   }
 
-  /* flag to determine whether deep format is used */
-  bool use_high_bit_depth = false, do_color_management = false;
-
-  if (ibuf->rect_float) {
-    use_high_bit_depth = true;
-
-    /* TODO unneeded when float images are correctly treated as linear always */
-    if (!is_data) {
-      do_color_management = true;
-    }
-  }
-
-  const int rectw = ibuf->x;
-  const int recth = ibuf->y;
-  uint *rect = ibuf->rect;
-  float *frect = NULL;
-  float *srgb_frect = NULL;
-
-  if (use_high_bit_depth) {
-    if (do_color_management) {
-      frect = srgb_frect = MEM_mallocN(ibuf->x * ibuf->y * sizeof(*srgb_frect) * 4,
-                                       "floar_buf_col_cor");
-      gpu_verify_high_bit_srgb_buffer(srgb_frect, ibuf);
-    }
-    else {
-      frect = ibuf->rect_float;
-    }
-  }
-
-  const bool mipmap = GPU_get_mipmap();
-
-#ifdef WITH_DDS
-  if (ibuf->ftype == IMB_FTYPE_DDS) {
-    GPU_create_gl_tex_compressed(&bindcode, rect, rectw, recth, textarget, mipmap, ima, ibuf);
-  }
-  else
-#endif
-  {
-    GPU_create_gl_tex(
-        &bindcode, rect, frect, rectw, recth, textarget, mipmap, use_high_bit_depth, ima);
-  }
-
-  /* mark as non-color data texture */
-  if (bindcode) {
-    if (is_data) {
-      ima->gpuflag |= IMA_GPU_IS_DATA;
-    }
-    else {
-      ima->gpuflag &= ~IMA_GPU_IS_DATA;
-    }
-  }
-
-  /* clean up */
-  if (srgb_frect) {
-    MEM_freeN(srgb_frect);
-  }
+  bindcode = gpu_texture_create_from_ibuf(ima, ibuf, textarget);
 
   BKE_image_release_ibuf(ima, ibuf, NULL);
 
@@ -349,15 +474,14 @@ GPUTexture *GPU_texture_from_blender(Image *ima, ImageUser *iuser, int textarget
   return *tex;
 }
 
-static void **gpu_gen_cube_map(
-    uint *rect, float *frect, int rectw, int recth, bool use_high_bit_depth)
+static void **gpu_gen_cube_map(uint *rect, float *frect, int rectw, int recth)
 {
-  size_t block_size = use_high_bit_depth ? sizeof(float[4]) : sizeof(uchar[4]);
+  size_t block_size = frect ? sizeof(float[4]) : sizeof(uchar[4]);
   void **sides = NULL;
   int h = recth / 2;
   int w = rectw / 3;
 
-  if ((use_high_bit_depth && frect == NULL) || (!use_high_bit_depth && rect == NULL) || w != h) {
+  if (w != h) {
     return sides;
   }
 
@@ -376,7 +500,7 @@ static void **gpu_gen_cube_map(
    * | NegZ | PosZ | PosY |
    * |______|______|______|
    */
-  if (use_high_bit_depth) {
+  if (frect) {
     float(*frectb)[4] = (float(*)[4])frect;
     float(**fsides)[4] = (float(**)[4])sides;
 
@@ -430,7 +554,7 @@ void GPU_create_gl_tex(uint *bind,
                        int recth,
                        int textarget,
                        bool mipmap,
-                       bool use_high_bit_depth,
+                       bool use_srgb,
                        Image *ima)
 {
   ImBuf *ibuf = NULL;
@@ -441,7 +565,7 @@ void GPU_create_gl_tex(uint *bind,
     rectw = smaller_power_of_2_limit(rectw);
     recth = smaller_power_of_2_limit(recth);
 
-    if (use_high_bit_depth) {
+    if (frect) {
       ibuf = IMB_allocFromBuffer(NULL, frect, tpx, tpy);
       IMB_scaleImBuf(ibuf, rectw, recth);
 
@@ -459,12 +583,15 @@ void GPU_create_gl_tex(uint *bind,
   glGenTextures(1, (GLuint *)bind);
   glBindTexture(textarget, *bind);
 
+  GLenum internal_format = (frect) ? GL_RGBA16F : (use_srgb) ? GL_SRGB8_ALPHA8 : GL_RGBA8;
+
   if (textarget == GL_TEXTURE_2D) {
-    if (use_high_bit_depth) {
-      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, rectw, recth, 0, GL_RGBA, GL_FLOAT, frect);
+    if (frect) {
+      glTexImage2D(GL_TEXTURE_2D, 0, internal_format, rectw, recth, 0, GL_RGBA, GL_FLOAT, frect);
     }
     else {
-      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, rectw, recth, 0, GL_RGBA, GL_UNSIGNED_BYTE, rect);
+      glTexImage2D(
+          GL_TEXTURE_2D, 0, internal_format, rectw, recth, 0, GL_RGBA, GL_UNSIGNED_BYTE, rect);
     }
 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, gpu_get_mipmap_filter(1));
@@ -484,15 +611,14 @@ void GPU_create_gl_tex(uint *bind,
     int w = rectw / 3, h = recth / 2;
 
     if (h == w && is_power_of_2_i(h) && !is_over_resolution_limit(textarget, h, w)) {
-      void **cube_map = gpu_gen_cube_map(rect, frect, rectw, recth, use_high_bit_depth);
-      GLenum informat = use_high_bit_depth ? GL_RGBA16F : GL_RGBA8;
-      GLenum type = use_high_bit_depth ? GL_FLOAT : GL_UNSIGNED_BYTE;
+      void **cube_map = gpu_gen_cube_map(rect, frect, rectw, recth);
+      GLenum type = frect ? GL_FLOAT : GL_UNSIGNED_BYTE;
 
       if (cube_map) {
         for (int i = 0; i < 6; i++) {
           glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i,
                        0,
-                       informat,
+                       internal_format,
                        w,
                        h,
                        0,
@@ -617,14 +743,14 @@ void GPU_create_gl_tex_compressed(
 #ifndef WITH_DDS
   (void)ibuf;
   /* Fall back to uncompressed if DDS isn't enabled */
-  GPU_create_gl_tex(bind, pix, NULL, x, y, textarget, mipmap, 0, ima);
+  GPU_create_gl_tex(bind, pix, NULL, x, y, textarget, mipmap, true, ima);
 #else
   glGenTextures(1, (GLuint *)bind);
   glBindTexture(textarget, *bind);
 
   if (textarget == GL_TEXTURE_2D && GPU_upload_dxt_texture(ibuf) == 0) {
     glDeleteTextures(1, (GLuint *)bind);
-    GPU_create_gl_tex(bind, pix, NULL, x, y, textarget, mipmap, 0, ima);
+    GPU_create_gl_tex(bind, pix, NULL, x, y, textarget, mipmap, true, ima);
   }
 
   glBindTexture(textarget, 0);
@@ -680,146 +806,20 @@ void GPU_paint_set_mipmap(Main *bmain, bool mipmap)
   }
 }
 
-/* check if image has been downscaled and do scaled partial update */
-static bool gpu_check_scaled_image(
-    ImBuf *ibuf, Image *ima, float *frect, int x, int y, int w, int h)
-{
-  if (is_over_resolution_limit(GL_TEXTURE_2D, ibuf->x, ibuf->y)) {
-    int x_limit = smaller_power_of_2_limit(ibuf->x);
-    int y_limit = smaller_power_of_2_limit(ibuf->y);
-
-    float xratio = x_limit / (float)ibuf->x;
-    float yratio = y_limit / (float)ibuf->y;
-
-    /* find new width, height and x,y gpu texture coordinates */
-
-    /* take ceiling because we will be losing 1 pixel due to rounding errors in x,y... */
-    int rectw = (int)ceil(xratio * w);
-    int recth = (int)ceil(yratio * h);
-
-    x *= xratio;
-    y *= yratio;
-
-    /* ...but take back if we are over the limit! */
-    if (rectw + x > x_limit) {
-      rectw--;
-    }
-    if (recth + y > y_limit) {
-      recth--;
-    }
-
-    GPU_texture_bind(ima->gputexture[TEXTARGET_TEXTURE_2D], 0);
-
-    /* float rectangles are already continuous in memory so we can use IMB_scaleImBuf */
-    if (frect) {
-      ImBuf *ibuf_scale = IMB_allocFromBuffer(NULL, frect, w, h);
-      IMB_scaleImBuf(ibuf_scale, rectw, recth);
-
-      glTexSubImage2D(
-          GL_TEXTURE_2D, 0, x, y, rectw, recth, GL_RGBA, GL_FLOAT, ibuf_scale->rect_float);
-
-      IMB_freeImBuf(ibuf_scale);
-    }
-    /* byte images are not continuous in memory so do manual interpolation */
-    else {
-      uchar *scalerect = MEM_mallocN(rectw * recth * sizeof(*scalerect) * 4, "scalerect");
-      uint *p = (uint *)scalerect;
-      int i, j;
-      float inv_xratio = 1.0f / xratio;
-      float inv_yratio = 1.0f / yratio;
-      for (i = 0; i < rectw; i++) {
-        float u = (x + i) * inv_xratio;
-        for (j = 0; j < recth; j++) {
-          float v = (y + j) * inv_yratio;
-          bilinear_interpolation_color_wrap(ibuf, (uchar *)(p + i + j * (rectw)), NULL, u, v);
-        }
-      }
-
-      glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, rectw, recth, GL_RGBA, GL_UNSIGNED_BYTE, scalerect);
-
-      MEM_freeN(scalerect);
-    }
-
-    if (GPU_get_mipmap()) {
-      glGenerateMipmap(GL_TEXTURE_2D);
-    }
-    else {
-      ima->gpuflag &= ~IMA_GPU_MIPMAP_COMPLETE;
-    }
-
-    GPU_texture_unbind(ima->gputexture[TEXTARGET_TEXTURE_2D]);
-
-    return true;
-  }
-
-  return false;
-}
-
 void GPU_paint_update_image(Image *ima, ImageUser *iuser, int x, int y, int w, int h)
 {
   ImBuf *ibuf = BKE_image_acquire_ibuf(ima, iuser, NULL);
 
   if ((ima->gputexture[TEXTARGET_TEXTURE_2D] == NULL) || (ibuf == NULL) || (w == 0) || (h == 0)) {
-    /* these cases require full reload still */
+    /* Full reload of texture. */
     GPU_free_image(ima);
   }
   else {
-    /* for the special case, we can do a partial update
-     * which is much quicker for painting */
-    GLint row_length, skip_pixels, skip_rows;
-
-    /* if color correction is needed, we must update the part that needs updating. */
-    if (ibuf->rect_float) {
-      float *buffer = MEM_mallocN(w * h * sizeof(float) * 4, "temp_texpaint_float_buf");
-      bool is_data = (ima->gpuflag & IMA_GPU_IS_DATA) != 0;
-      IMB_partial_rect_from_float(ibuf, buffer, x, y, w, h, is_data);
-
-      if (gpu_check_scaled_image(ibuf, ima, buffer, x, y, w, h)) {
-        MEM_freeN(buffer);
-        BKE_image_release_ibuf(ima, ibuf, NULL);
-        return;
-      }
-
-      GPU_texture_bind(ima->gputexture[TEXTARGET_TEXTURE_2D], 0);
-      glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_FLOAT, buffer);
-
-      MEM_freeN(buffer);
-
-      if (GPU_get_mipmap()) {
-        glGenerateMipmap(GL_TEXTURE_2D);
-      }
-      else {
-        ima->gpuflag &= ~IMA_GPU_MIPMAP_COMPLETE;
-      }
-
-      GPU_texture_unbind(ima->gputexture[TEXTARGET_TEXTURE_2D]);
-
-      BKE_image_release_ibuf(ima, ibuf, NULL);
-      return;
-    }
-
-    if (gpu_check_scaled_image(ibuf, ima, NULL, x, y, w, h)) {
-      BKE_image_release_ibuf(ima, ibuf, NULL);
-      return;
-    }
-
+    /* Partial update of texture. */
     GPU_texture_bind(ima->gputexture[TEXTARGET_TEXTURE_2D], 0);
 
-    glGetIntegerv(GL_UNPACK_ROW_LENGTH, &row_length);
-    glGetIntegerv(GL_UNPACK_SKIP_PIXELS, &skip_pixels);
-    glGetIntegerv(GL_UNPACK_SKIP_ROWS, &skip_rows);
-
-    glPixelStorei(GL_UNPACK_ROW_LENGTH, ibuf->x);
-    glPixelStorei(GL_UNPACK_SKIP_PIXELS, x);
-    glPixelStorei(GL_UNPACK_SKIP_ROWS, y);
-
-    glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, w, h, GL_RGBA, GL_UNSIGNED_BYTE, ibuf->rect);
-
-    glPixelStorei(GL_UNPACK_ROW_LENGTH, row_length);
-    glPixelStorei(GL_UNPACK_SKIP_PIXELS, skip_pixels);
-    glPixelStorei(GL_UNPACK_SKIP_ROWS, skip_rows);
+    gpu_texture_update_from_ibuf(ibuf, x, y, w, h);
 
-    /* see comment above as to why we are using gpu mipmap generation here */
     if (GPU_get_mipmap()) {
       glGenerateMipmap(GL_TEXTURE_2D);
     }
@@ -1242,7 +1242,7 @@ static void gpu_free_image_immediate(Image *ima)
     }
   }
 
-  ima->gpuflag &= ~(IMA_GPU_MIPMAP_COMPLETE | IMA_GPU_IS_DATA);
+  ima->gpuflag &= ~(IMA_GPU_MIPMAP_COMPLETE);
 }
 
 void GPU_free_image(Image *ima)
diff --git a/source/blender/gpu/intern/gpu_material.c b/source/blender/gpu/intern/gpu_material.c
index 1a668a48eed..6aa13b0d8ca 100644
--- a/source/blender/gpu/intern/gpu_material.c
+++ b/source/blender/gpu/intern/gpu_material.c
@@ -597,15 +597,6 @@ eGPUMaterialStatus GPU_material_status(GPUMaterial *mat)
 
 /* Code generation */
 
-bool GPU_material_do_color_management(GPUMaterial *mat)
-{
-  if (!BKE_scene_check_color_management_enabled(mat->scene)) {
-    return false;
-  }
-
-  return true;
-}
-
 bool GPU_material_use_domain_surface(GPUMaterial *mat)
 {
   return (mat->domain & GPU_DOMAIN_SURFACE);
diff --git a/source/blender/gpu/intern/gpu_texture.c b/source/blender/gpu/intern/gpu_texture.c
index ad4831ed903..58d0dd5576f 100644
--- a/source/blender/gpu/intern/gpu_texture.c
+++ b/source/blender/gpu/intern/gpu_texture.c
@@ -1081,7 +1081,7 @@ GPUTexture *GPU_texture_from_preview(PreviewImage *prv, int mipmap)
   /* this binds a texture, so that's why we restore it to 0 */
   if (bindcode == 0) {
     GPU_create_gl_tex(
-        &bindcode, prv->rect[0], NULL, prv->w[0], prv->h[0], GL_TEXTURE_2D, mipmap, 0, NULL);
+        &bindcode, prv->rect[0], NULL, prv->w[0], prv->h[0], GL_TEXTURE_2D, mipmap, false, NULL);
   }
   if (tex) {
     tex->bindcode = bindcode;
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index 2f80bc95a0c..5596940cbf6 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -117,38 +117,6 @@ void hsv_to_rgb(vec4 hsv, out vec4 outcol)
   outcol = vec4(rgb, hsv.w);
 }
 
-float srgb_to_linearrgb(float c)
-{
-  if (c < 0.04045)
-    return (c < 0.0) ? 0.0 : c * (1.0 / 12.92);
-  else
-    return pow((c + 0.055) * (1.0 / 1.055), 2.4);
-}
-
-float linearrgb_to_srgb(float c)
-{
-  if (c < 0.0031308)
-    return (c < 0.0) ? 0.0 : c * 12.92;
-  else
-    return 1.055 * pow(c, 1.0 / 2.4) - 0.055;
-}
-
-void srgb_to_linearrgb(vec4 col_from, out vec4 col_to)
-{
-  col_to.r = srgb_to_linearrgb(col_from.r);
-  col_to.g = srgb_to_linearrgb(col_from.g);
-  col_to.b = srgb_to_linearrgb(col_from.b);
-  col_to.a = col_from.a;
-}
-
-void linearrgb_to_srgb(vec4 col_from, out vec4 col_to)
-{
-  col_to.r = linearrgb_to_srgb(col_from.r);
-  col_to.g = linearrgb_to_srgb(col_from.g);
-  col_to.b = linearrgb_to_srgb(col_from.b);
-  col_to.a = col_from.a;
-}
-
 void color_to_normal_new_shading(vec3 color, out vec3 normal)
 {
   normal = vec3(2.0) * color - vec3(1.0);
@@ -2330,6 +2298,21 @@ void node_tex_environment_empty(vec3 co, out vec4 color)
 /* 16bits floats limits. Higher/Lower values produce +/-inf. */
 #define safe_color(a) (clamp(a, -65520.0, 65520.0))
 
+void tex_color_alpha_clear(vec4 color, out vec4 result)
+{
+  result = vec4(color.rgb, 1.0);
+}
+
+void tex_color_alpha_unpremultiply(vec4 color, out vec4 result)
+{
+  if (color.a == 0.0 || color.a == 1.0) {
+    result = vec4(color.rgb, 1.0);
+  }
+  else {
+    result = vec4(color.rgb / color.a, 1.0);
+  }
+}
+
 void node_tex_image_linear(vec3 co, sampler2D ima, out vec4 color, out float alpha)
 {
   color = safe_color(texture(ima, co.xy));