Color management fixes

Now it's a bit more robust, tagging images with profiles when they're loaded, 
which then get interpreted later on by conversion functions. Just Linear RGB 
and sRGB profiles at the moment, same as before.

This commit fixes Martin's problem with EXRs and Multilayer images loading/
saving too dark, and it also makes the sequence editor work correctly with it too.

Also fixes:
[#19647] gamma correction with color management is reset when resetting Curve
[#19454] 2.5: Dither does not work when Color management is enabled

1 files changed, 45 insertions, 30 deletions

diff --git a/source/blender/imbuf/intern/divers.c b/source/blender/imbuf/intern/divers.c
index 35be1f716e6..bcf913e6caf 100644
--- a/source/blender/imbuf/intern/divers.c
+++ b/source/blender/imbuf/intern/divers.c
@@ -175,12 +175,14 @@ void IMB_gamwarp(struct ImBuf *ibuf, double gamma)
 }
 
 
+/* assume converting from linear float to sRGB byte */
 void IMB_rect_from_float(struct ImBuf *ibuf)
 {
 	/* quick method to convert floatbuf to byte */
 	float *tof = (float *)ibuf->rect_float;
-	float dither= ibuf->dither;
-	float srgb[3];
+	int do_dither = ibuf->dither != 0.f;
+	float dither= ibuf->dither / 255.0;
+	float srgb[4];
 	int i, channels= ibuf->channels;
 	short profile= ibuf->profile;
 	unsigned char *to = (unsigned char *) ibuf->rect;
@@ -195,7 +197,7 @@ void IMB_rect_from_float(struct ImBuf *ibuf)
 		for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof++)
 			to[1]= to[2]= to[3]= to[0] = FTOCHAR(tof[0]);
 	}
-	else if (profile == IB_PROFILE_SRGB) {
+	else if (profile == IB_PROFILE_LINEAR_RGB) {
 		if(channels == 3) {
 			for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=3) {
 				srgb[0]= linearrgb_to_srgb(tof[0]);
@@ -209,10 +211,26 @@ void IMB_rect_from_float(struct ImBuf *ibuf)
 			}
 		}
 		else if (channels == 4) {
-			floatbuf_to_srgb_byte(tof, to, 0, ibuf->x, 0, ibuf->y, ibuf->x);
+			if (dither != 0.f) {
+				for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=4) {
+					const float d = (BLI_frand()-0.5)*dither;
+					
+					srgb[0]= d + linearrgb_to_srgb(tof[0]);
+					srgb[1]= d + linearrgb_to_srgb(tof[1]);
+					srgb[2]= d + linearrgb_to_srgb(tof[2]);
+					srgb[3]= d + tof[3]; 
+					
+					to[0] = FTOCHAR(srgb[0]);
+					to[1] = FTOCHAR(srgb[1]);
+					to[2] = FTOCHAR(srgb[2]);
+					to[3] = FTOCHAR(srgb[3]);
+				}
+			} else {
+				floatbuf_to_srgb_byte(tof, to, 0, ibuf->x, 0, ibuf->y, ibuf->x);
+			}
 		}
 	}
-	else if(ELEM(profile, IB_PROFILE_NONE, IB_PROFILE_LINEAR_RGB) && dither==0.0f) {
+	else if(ELEM(profile, IB_PROFILE_NONE, IB_PROFILE_SRGB)) {
 		if(channels==3) {
 			for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=3) {
 				to[0] = FTOCHAR(tof[0]);
@@ -222,32 +240,26 @@ void IMB_rect_from_float(struct ImBuf *ibuf)
 			}
 		}
 		else {
-			for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=4) {
-				to[0] = FTOCHAR(tof[0]);
-				to[1] = FTOCHAR(tof[1]);
-				to[2] = FTOCHAR(tof[2]);
-				to[3] = FTOCHAR(tof[3]);
+			if (dither != 0.f) {
+				float col[3];		
+				for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=4) {
+					const float d = (BLI_frand()-0.5)*dither;
+					const float col[4] = {d+tof[0], d+tof[1], d+tof[2], d+tof[3]};
+					to[0] = FTOCHAR(col[0]);
+					to[1] = FTOCHAR(col[1]);
+					to[2] = FTOCHAR(col[2]);
+					to[3] = FTOCHAR(col[3]);
+				}
+			} else {
+				for (i = ibuf->x * ibuf->y; i > 0; i--, to+=4, tof+=4) {
+					to[0] = FTOCHAR(tof[0]);
+					to[1] = FTOCHAR(tof[1]);
+					to[2] = FTOCHAR(tof[2]);
+					to[3] = FTOCHAR(tof[3]);
+				}
 			}
 		}
 	}
-	else {
-		float dither_value, col;
-		dither= dither/255.0f;
-		for (i = ibuf->x * ibuf->y; i > 0; i--) {
-			dither_value = (BLI_frand()-0.5)*dither; 
-			col= tof[0] + dither_value;
-			to[0] = FTOCHAR(col);
-			col= tof[1] + dither_value;
-			to[1] = FTOCHAR(col);
-			col= tof[2] + dither_value;
-			to[2] = FTOCHAR(col);
-			col= tof[3] + dither_value;
-			to[3] = FTOCHAR(col);
-
-			to += 4; 
-			tof += 4;
-		}
-	}
 }
 
 void IMB_float_from_rect(struct ImBuf *ibuf)
@@ -263,8 +275,11 @@ void IMB_float_from_rect(struct ImBuf *ibuf)
 		tof = ibuf->rect_float;
 	}
 	
-	if (ibuf->profile == IB_PROFILE_SRGB) {
-		/* convert from srgb to linear rgb */
+	/* Float bufs should be stored linear */
+
+	if (ibuf->profile != IB_PROFILE_NONE) {
+		/* if the image has been given a profile then we're working 
+		 * with color management in mind, so convert it to linear space */
 		
 		for (i = ibuf->x * ibuf->y; i > 0; i--) 
 		{