Color management: add "Color Unpremultiply" option for images and render settings.

For premultiplied alpha images, this makes any color space conversion for the image
or render output work on color without alpha multiplied in.

This is typically useful to avoid fringing when the image was or will be composited
over a light background. If the image will be composited over a black background on
the other hand, leaving this option off will give correct results.

In an ideal world, there should never be any color space conversion on images with
alpha, since it's undefined what to do then, but in practice it's useful to have
this option.

Patch by Troy Sobotka, with changes by me.

16 files changed, 87 insertions, 61 deletions

diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index 354a5265f90..a5c8f5c905d 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -285,6 +285,10 @@ static void image_assign_ibuf(Image *ima, ImBuf *ibuf, int index, int frame)
 				break;
 
 		ibuf->index= index;
+		if(ima->flag & IMA_CM_PREDIVIDE)
+			ibuf->flags |= IB_cm_predivide;
+		else
+			ibuf->flags &= ~IB_cm_predivide;
 
 		/* this function accepts link==NULL */
 		BLI_insertlinkbefore(&ima->ibufs, link, ibuf);
@@ -2304,9 +2308,17 @@ static ImBuf *image_get_render_result(Image *ima, ImageUser *iuser, void **lock_
 
 	/* since its possible to access the buffer from the image directly, set the profile [#25073] */
 	ibuf->profile= (iuser->scene->r.color_mgt_flag & R_COLOR_MANAGEMENT) ? IB_PROFILE_LINEAR_RGB : IB_PROFILE_NONE;
-
 	ibuf->dither= dither;
 
+	if(iuser->scene->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE) {
+		ibuf->flags |= IB_cm_predivide;
+		ima->flag |= IMA_CM_PREDIVIDE;
+	}
+	else {
+		ibuf->flags &= ~IB_cm_predivide;
+		ima->flag &= ~IMA_CM_PREDIVIDE;
+	}
+
 	ima->ok= IMA_OK_LOADED;
 
 	return ibuf;
diff --git a/source/blender/editors/include/BIF_glutil.h b/source/blender/editors/include/BIF_glutil.h
index cd3d87a8979..33e9192a23e 100644
--- a/source/blender/editors/include/BIF_glutil.h
+++ b/source/blender/editors/include/BIF_glutil.h
@@ -136,13 +136,8 @@ void glaDrawPixelsSafe		(float x, float y, int img_w, int img_h, int row_w, int
 	 * is expected to be in RGBA byte or float format, and the 
 	 * modelview and projection matrices are assumed to define a 
 	 * 1-to-1 mapping to screen space.
-	 * @param gamma_correct Optionally gamma correct float sources to sRGB for display
 	 */
 
-	/* only for float rects, converts to 32 bits and draws */
-void glaDrawPixelsSafe_to32(float fx, float fy, int img_w, int img_h, int row_w, float *rectf, int gamma_correct);
-
-
 void glaDrawPixelsTex		(float x, float y, int img_w, int img_h, int format, void *rect);
 
 void glaDrawPixelsTexScaled(float x, float y, int img_w, int img_h, int format, void *rect, float scaleX, float scaleY);
diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index bff93fea067..e4597d6afc3 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -138,11 +138,14 @@ void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, volat
 	rectf+= 4*(rr->rectx*ymin + xmin);
 	rectc= (unsigned char*)(ibuf->rect + ibuf->x*rymin + rxmin);
 
-	if(scene && (scene->r.color_mgt_flag & R_COLOR_MANAGEMENT))
+	if(scene && (scene->r.color_mgt_flag & R_COLOR_MANAGEMENT)) {
 		profile_from= IB_PROFILE_LINEAR_RGB;
-	else
+		predivide= (scene->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE);
+	}
+	else {
 		profile_from= IB_PROFILE_SRGB;
-	predivide= 0;
+		predivide= 0;
+	}
 
 	IMB_buffer_byte_from_float(rectc, rectf,
 		4, ibuf->dither, IB_PROFILE_SRGB, profile_from, predivide,
diff --git a/source/blender/editors/render/render_preview.c b/source/blender/editors/render/render_preview.c
index feff1e05d60..86328ca2a64 100644
--- a/source/blender/editors/render/render_preview.c
+++ b/source/blender/editors/render/render_preview.c
@@ -460,12 +460,15 @@ static int ed_preview_draw_rect(ScrArea *sa, Scene *sce, ID *id, int split, int
 	Render *re;
 	RenderResult rres;
 	char name[32];
-	int do_gamma_correct=0;
+	int do_gamma_correct=0, do_predivide=0;
 	int offx=0, newx= rect->xmax-rect->xmin, newy= rect->ymax-rect->ymin;
 
 	if (id && GS(id->name) != ID_TE) {
 		/* exception: don't color manage texture previews - show the raw values */
-		if (sce) do_gamma_correct = sce->r.color_mgt_flag & R_COLOR_MANAGEMENT;
+		if (sce) {
+			do_gamma_correct = sce->r.color_mgt_flag & R_COLOR_MANAGEMENT;
+			do_predivide = sce->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE;
+		}
 	}
 
 	if(!split || first) sprintf(name, "Preview %p", (void *)sa);
@@ -488,10 +491,28 @@ static int ed_preview_draw_rect(ScrArea *sa, Scene *sce, ID *id, int split, int
 	if(rres.rectf) {
 		
 		if(ABS(rres.rectx-newx)<2 && ABS(rres.recty-newy)<2) {
+
 			newrect->xmax= MAX2(newrect->xmax, rect->xmin + rres.rectx + offx);
 			newrect->ymax= MAX2(newrect->ymax, rect->ymin + rres.recty);
 
-			glaDrawPixelsSafe_to32(rect->xmin+offx, rect->ymin, rres.rectx, rres.recty, rres.rectx, rres.rectf, do_gamma_correct);
+			if(rres.rectx && rres.recty) {
+				/* temporary conversion to byte for drawing */
+				float fx= rect->xmin + offx;
+				float fy= rect->ymin;
+				int profile_from= (do_gamma_correct)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
+				int dither= 0;
+				unsigned char *rect_byte;
+
+				rect_byte= MEM_mallocN(rres.rectx*rres.recty*sizeof(int), "ed_preview_draw_rect");
+
+				IMB_buffer_byte_from_float(rect_byte, rres.rectf,
+					4, dither, IB_PROFILE_SRGB, profile_from, do_predivide, 
+					rres.rectx, rres.recty, rres.rectx, rres.rectx);
+
+				glaDrawPixelsSafe(fx, fy, rres.rectx, rres.recty, rres.rectx, GL_RGBA, GL_UNSIGNED_BYTE, rect_byte);
+
+				MEM_freeN(rect_byte);
+			}
 
 			RE_ReleaseResultImage(re);
 			return 1;
diff --git a/source/blender/editors/screen/glutil.c b/source/blender/editors/screen/glutil.c
index 8f04940efd6..0b231ee7b96 100644
--- a/source/blender/editors/screen/glutil.c
+++ b/source/blender/editors/screen/glutil.c
@@ -45,9 +45,6 @@
 #include "BIF_gl.h"
 #include "BIF_glutil.h"
 
-#include "IMB_imbuf.h"
-#include "IMB_imbuf_types.h"
-
 #ifndef GL_CLAMP_TO_EDGE
 #define GL_CLAMP_TO_EDGE                        0x812F
 #endif
@@ -562,27 +559,6 @@ void glaDrawPixelsTex(float x, float y, int img_w, int img_h, int format, void *
 	glaDrawPixelsTexScaled(x, y, img_w, img_h, format, rect, 1.0f, 1.0f);
 }
 
-/* row_w is unused but kept for completeness */
-void glaDrawPixelsSafe_to32(float fx, float fy, int img_w, int img_h, int UNUSED(row_w), float *rectf, int do_gamma_correct)
-{
-	unsigned char *rect32;
-	int profile_from= (do_gamma_correct)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
-	int predivide= 0;
-	
-	/* copy imgw-imgh to a temporal 32 bits rect */
-	if(img_w<1 || img_h<1) return;
-	
-	rect32= MEM_mallocN(img_w*img_h*sizeof(int), "temp 32 bits");
-	
-	IMB_buffer_byte_from_float(rect32, rectf,
-		4, 0, IB_PROFILE_SRGB, profile_from, predivide, 
-		img_w, img_h, img_w, img_w);
-	
-	glaDrawPixelsSafe(fx, fy, img_w, img_h, img_w, GL_RGBA, GL_UNSIGNED_BYTE, rect32);
-
-	MEM_freeN(rect32);
-}
-
 void glaDrawPixelsSafe(float x, float y, int img_w, int img_h, int row_w, int format, int type, void *rect)
 {
 	float xzoom= glaGetOneFloat(GL_ZOOM_X);
diff --git a/source/blender/editors/space_image/image_buttons.c b/source/blender/editors/space_image/image_buttons.c
index c647ff3df53..8d8c79386c5 100644
--- a/source/blender/editors/space_image/image_buttons.c
+++ b/source/blender/editors/space_image/image_buttons.c
@@ -750,7 +750,9 @@ void uiTemplateImage(uiLayout *layout, bContext *C, PointerRNA *ptr, const char
 					uiLayoutSetActive(row, RNA_boolean_get(&imaptr, "use_fields"));
 					uiItemR(row, &imaptr, "field_order", UI_ITEM_R_EXPAND, NULL, ICON_NONE);
 					
-					uiItemR(split, &imaptr, "use_premultiply", 0, NULL, ICON_NONE);
+					row= uiLayoutRow(layout, 0);
+					uiItemR(row, &imaptr, "use_premultiply", 0, NULL, ICON_NONE);
+					uiItemR(row, &imaptr, "use_color_unpremultiply", 0, NULL, ICON_NONE);
 				}
 			}
 
diff --git a/source/blender/editors/space_node/space_node.c b/source/blender/editors/space_node/space_node.c
index 1a808e8ee5f..9d4c5705bd1 100644
--- a/source/blender/editors/space_node/space_node.c
+++ b/source/blender/editors/space_node/space_node.c
@@ -248,12 +248,10 @@ static void node_area_listener(ScrArea *sa, wmNotifier *wmn)
 		case NC_IMAGE:
 			if (wmn->action == NA_EDITED) {
 				if(type==NTREE_COMPOSIT) {
-					Scene *scene= wmn->window->screen->scene;
-					
 					/* note that nodeUpdateID is already called by BKE_image_signal() on all
 					 * scenes so really this is just to know if the images is used in the compo else
 					 * painting on images could become very slow when the compositor is open. */
-					if(nodeUpdateID(scene->nodetree, wmn->reference))
+					if(nodeUpdateID(snode->nodetree, wmn->reference))
 						ED_area_tag_refresh(sa);
 				}
 			}
diff --git a/source/blender/imbuf/IMB_imbuf_types.h b/source/blender/imbuf/IMB_imbuf_types.h
index 5ce3d63fe86..adf6f4a143b 100644
--- a/source/blender/imbuf/IMB_imbuf_types.h
+++ b/source/blender/imbuf/IMB_imbuf_types.h
@@ -158,6 +158,7 @@ typedef struct ImBuf {
 #define IB_tiles			(1 << 10)
 #define IB_tilecache		(1 << 11)
 #define IB_premul			(1 << 12)
+#define IB_cm_predivide		(1 << 13)
 
 /*
  * The bit flag is stored in the ImBuf.ftype variable.
diff --git a/source/blender/imbuf/intern/divers.c b/source/blender/imbuf/intern/divers.c
index 8a3f6358c5b..0dfc1852e29 100644
--- a/source/blender/imbuf/intern/divers.c
+++ b/source/blender/imbuf/intern/divers.c
@@ -453,7 +453,8 @@ void IMB_buffer_byte_from_byte(uchar *rect_to, const uchar *rect_from,
 
 void IMB_rect_from_float(struct ImBuf *ibuf)
 {
-	int predivide= 0, profile_from;
+	int predivide= (ibuf->flags & IB_cm_predivide);
+	int profile_from;
 
 	/* verify we have a float buffer */
 	if(ibuf->rect_float==NULL)
@@ -485,7 +486,8 @@ void IMB_partial_rect_from_float(struct ImBuf *ibuf, float *buffer, int x, int y
 {
 	float *rect_float;
 	uchar *rect_byte;
-	int predivide= 0, profile_from;
+	int predivide= (ibuf->flags & IB_cm_predivide);
+	int profile_from;
 
 	/* verify we have a float buffer */
 	if(ibuf->rect_float==NULL || buffer==NULL)
@@ -521,7 +523,8 @@ void IMB_partial_rect_from_float(struct ImBuf *ibuf, float *buffer, int x, int y
 
 void IMB_float_from_rect(struct ImBuf *ibuf)
 {
-	int predivide= 0, profile_from;
+	int predivide= (ibuf->flags & IB_cm_predivide);
+	int profile_from;
 
 	/* verify if we byte and float buffers */
 	if(ibuf->rect==NULL)
@@ -546,7 +549,7 @@ void IMB_float_from_rect(struct ImBuf *ibuf)
 /* no profile conversion */
 void IMB_float_from_rect_simple(struct ImBuf *ibuf)
 {
-	int predivide= 0;
+	int predivide= (ibuf->flags & IB_cm_predivide);
 
 	if(ibuf->rect_float==NULL)
 		imb_addrectfloatImBuf(ibuf);
@@ -558,7 +561,8 @@ void IMB_float_from_rect_simple(struct ImBuf *ibuf)
 
 void IMB_convert_profile(struct ImBuf *ibuf, int profile)
 {
-	int predivide= 0, profile_from, profile_to;
+	int predivide= (ibuf->flags & IB_cm_predivide);
+	int profile_from, profile_to;
 
 	if(ibuf->profile == profile)
 		return;
@@ -599,7 +603,8 @@ void IMB_convert_profile(struct ImBuf *ibuf, int profile)
  * if the return  */
 float *IMB_float_profile_ensure(struct ImBuf *ibuf, int profile, int *alloc)
 {
-	int predivide= 0, profile_from, profile_to;
+	int predivide= (ibuf->flags & IB_cm_predivide);
+	int profile_from, profile_to;
 
 	/* determine profiles */
 	if(ibuf->profile == IB_PROFILE_NONE)
diff --git a/source/blender/makesdna/DNA_image_types.h b/source/blender/makesdna/DNA_image_types.h
index fc8807d0f7c..a1b0ab06ecd 100644
--- a/source/blender/makesdna/DNA_image_types.h
+++ b/source/blender/makesdna/DNA_image_types.h
@@ -112,14 +112,14 @@ typedef struct Image {
 /* **************** IMAGE ********************* */
 
 /* Image.flag */
-#define IMA_FIELDS		1
-#define IMA_STD_FIELD	2
-#define IMA_DO_PREMUL	4
-
-#define	IMA_REFLECT		16
-#define IMA_NOCOLLECT   32
-#define IMA_DEPRECATED	64
-#define IMA_OLD_PREMUL	128
+#define IMA_FIELDS			1
+#define IMA_STD_FIELD		2
+#define IMA_DO_PREMUL		4
+#define IMA_REFLECT			16
+#define IMA_NOCOLLECT   	32
+#define IMA_DEPRECATED		64
+#define IMA_OLD_PREMUL		128
+#define IMA_CM_PREDIVIDE	256
 
 /* Image.tpageflag */
 #define IMA_TILES			1
diff --git a/source/blender/makesdna/DNA_scene_types.h b/source/blender/makesdna/DNA_scene_types.h
index d1ab12433fb..9b49bc53ef3 100644
--- a/source/blender/makesdna/DNA_scene_types.h
+++ b/source/blender/makesdna/DNA_scene_types.h
@@ -1100,7 +1100,8 @@ typedef struct Scene {
 #define R_ALPHAKEY		2
 
 /* color_mgt_flag */
-#define R_COLOR_MANAGEMENT	1
+#define R_COLOR_MANAGEMENT              (1 << 0)
+#define R_COLOR_MANAGEMENT_PREDIVIDE    (1 << 1)
 
 /* subimtype, flag options for imtype */
 #define R_OPENEXR_HALF    1                                      /*deprecated*/
diff --git a/source/blender/makesrna/intern/rna_image.c b/source/blender/makesrna/intern/rna_image.c
index 6f6a27abe7c..9e7f4a349e7 100644
--- a/source/blender/makesrna/intern/rna_image.c
+++ b/source/blender/makesrna/intern/rna_image.c
@@ -40,6 +40,7 @@
 #include "BKE_image.h"
 
 #include "WM_types.h"
+#include "WM_api.h"
 
 static EnumPropertyItem image_source_items[]= {
 	{IMA_SRC_FILE, "FILE", 0, "Single Image", "Single image file"},
@@ -110,6 +111,7 @@ static void rna_Image_reload_update(Main *UNUSED(bmain), Scene *UNUSED(scene), P
 {
 	Image *ima= ptr->id.data;
 	BKE_image_signal(ima, NULL, IMA_SIGNAL_RELOAD);
+	WM_main_add_notifier(NC_IMAGE|NA_EDITED, &ima->id);
 	DAG_id_tag_update(&ima->id, 0);
 }
 
@@ -475,6 +477,11 @@ static void rna_def_image(BlenderRNA *brna)
 	RNA_def_property_boolean_sdna(prop, NULL, "flag", IMA_DO_PREMUL);
 	RNA_def_property_ui_text(prop, "Premultiply", "Convert RGB from key alpha to premultiplied alpha");
 	RNA_def_property_update(prop, NC_IMAGE|ND_DISPLAY, "rna_Image_reload_update");
+	
+	prop= RNA_def_property(srna, "use_color_unpremultiply", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "flag", IMA_CM_PREDIVIDE);
+	RNA_def_property_ui_text(prop, "Color Unpremultiply", "For premultiplied alpha images, do color space conversion on colors without alpha, to avoid fringing for images with light backgrounds");
+	RNA_def_property_update(prop, NC_IMAGE|ND_DISPLAY, "rna_Image_reload_update");
 
 	prop= RNA_def_property(srna, "is_dirty", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_funcs(prop, "rna_Image_dirty_get", NULL);
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index 54267725fe2..b69ca64773c 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -3228,7 +3228,11 @@ static void rna_def_scene_render_data(BlenderRNA *brna)
 	RNA_def_property_boolean_sdna(prop, NULL, "color_mgt_flag", R_COLOR_MANAGEMENT);
 	RNA_def_property_ui_text(prop, "Color Management", "Use linear workflow - gamma corrected imaging pipeline");
 	RNA_def_property_update(prop, NC_SCENE|ND_RENDER_OPTIONS, "rna_RenderSettings_color_management_update");
-
+	
+	prop= RNA_def_property(srna, "use_color_unpremultiply", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "color_mgt_flag", R_COLOR_MANAGEMENT_PREDIVIDE);
+	RNA_def_property_ui_text(prop, "Color Unpremultipy", "For premultiplied alpha render output, do color space conversion on colors without alpha, to avoid fringing on light backgrounds");
+	RNA_def_property_update(prop, NC_SCENE|ND_RENDER_OPTIONS, NULL);
 	
 	prop= RNA_def_property(srna, "use_file_extension", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "scemode", R_EXTENSION);
diff --git a/source/blender/nodes/composite/node_composite_util.c b/source/blender/nodes/composite/node_composite_util.c
index 8aaf1771b68..72037f232ad 100644
--- a/source/blender/nodes/composite/node_composite_util.c
+++ b/source/blender/nodes/composite/node_composite_util.c
@@ -607,7 +607,7 @@ void generate_preview(void *data, bNode *node, CompBuf *stackbuf)
 	bNodePreview *preview= node->preview;
 	int xsize, ysize;
 	int profile_from= (rd->color_mgt_flag & R_COLOR_MANAGEMENT)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
-	int predivide= 0;
+	int predivide= (rd->color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE);
 	int dither= 0;
 	unsigned char *rect;
 	
diff --git a/source/blender/nodes/composite/nodes/node_composite_image.c b/source/blender/nodes/composite/nodes/node_composite_image.c
index fd7c87adea2..57b5cec4256 100644
--- a/source/blender/nodes/composite/nodes/node_composite_image.c
+++ b/source/blender/nodes/composite/nodes/node_composite_image.c
@@ -62,7 +62,7 @@ static bNodeSocketTemplate cmp_node_rlayers_out[]= {
 float *node_composit_get_float_buffer(RenderData *rd, ImBuf *ibuf, int *alloc)
 {
 	float *rect;
-	int predivide= 0;
+	int predivide= (ibuf->flags & IB_cm_predivide);
 
 	*alloc= FALSE;
 
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index 7713dcffc5c..555d5c12a86 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -1154,7 +1154,7 @@ void RE_ResultGet32(Render *re, unsigned int *rect)
 	}
 	else if(rres.rectf) {
 		int profile_from= (re->r.color_mgt_flag & R_COLOR_MANAGEMENT)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
-		int predivide= 0;
+		int predivide= (re->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE);
 		int dither= 0;
 
 		IMB_buffer_byte_from_float((unsigned char*)rect, rres.rectf,
@@ -2556,7 +2556,7 @@ static void do_render_seq(Render * re)
 			 * render engine delivers */
 			int profile_to= (re->r.color_mgt_flag & R_COLOR_MANAGEMENT)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
 			int profile_from= (ibuf->profile == IB_PROFILE_LINEAR_RGB)? IB_PROFILE_LINEAR_RGB: IB_PROFILE_SRGB;
-			int predivide= 0;
+			int predivide= (re->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE);
 
 			if (!rr->rectf)
 				rr->rectf= MEM_mallocN(4*sizeof(float)*rr->rectx*rr->recty, "render_seq rectf");
@@ -2995,7 +2995,8 @@ static int do_write_image_or_movie(Render *re, Main *bmain, Scene *scene, bMovie
 			}
 		}
 		else {
-			ImBuf *ibuf= IMB_allocImBuf(rres.rectx, rres.recty, scene->r.im_format.planes, 0);
+			int flags = (scene->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE)? IB_cm_predivide: 0;
+			ImBuf *ibuf= IMB_allocImBuf(rres.rectx, rres.recty, scene->r.im_format.planes, flags);
 			
 			/* if not exists, BKE_write_ibuf makes one */
 			ibuf->rect= (unsigned int *)rres.rect32;