Colour Management

- 1st stage: Linear Workflow

This implements automatic linear workflow in Blender's renderer. With the 
new Colour Management option on in the Render buttons, all inputs to the 
renderer and compositor are converted to linear colour space before 
rendering, and gamma corrected afterwards. In essence, this makes all 
manual gamma correction with nodes, etc unnecessary, since it's done 
automatically through the pipeline.

It's all explained much better in the notes/doc here, so please have a look:
http://wiki.blender.org/index.php/Dev:Source/Blender/Architecture/Colour_Management

And an example of the sort of difference it makes:
http://mke3.net/blender/devel/rendering/b25_colormanagement_test01.jpg

This also enables Colour Management in the default B.blend, and changes the 
default lamp falloff to inverse square, which is more correct, and much 
easier to use now it's all gamma corrected properly.

Next step is to look into profiles/soft proofing for the compositor.

Thanks to brecht for reviewing and fixing some oversights!

2 files changed, 48 insertions, 29 deletions

diff --git a/source/blender/editors/screen/glutil.c b/source/blender/editors/screen/glutil.c
index a23487effa1..5312ca26906 100644
--- a/source/blender/editors/screen/glutil.c
+++ b/source/blender/editors/screen/glutil.c
@@ -35,6 +35,7 @@
 #include "DNA_listBase.h"
 
 #include "BKE_utildefines.h"
+#include "BKE_colortools.h"
 
 #include "BLI_arithb.h"
 #include "BLI_threads.h"
@@ -482,27 +483,20 @@ 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);
 }
 
-void glaDrawPixelsSafe_to32(float fx, float fy, int img_w, int img_h, int row_w, float *rectf)
+void glaDrawPixelsSafe_to32(float fx, float fy, int img_w, int img_h, int row_w, float *rectf, int gamma_correct)
 {
-	float *rf;
-	int x, y;
-	char *rect32, *rc;
+	unsigned char *rect32;
 	
 	/* copy imgw-imgh to a temporal 32 bits rect */
 	if(img_w<1 || img_h<1) return;
 	
-	rc= rect32= MEM_mallocN(img_w*img_h*sizeof(int), "temp 32 bits");
+	rect32= MEM_mallocN(img_w*img_h*sizeof(int), "temp 32 bits");
 	
-	for(y=0; y<img_h; y++) {
-		rf= rectf;
-		for(x=0; x<img_w; x++, rf+=4, rc+=4) {
-			rc[0]= FTOCHAR(rf[0]);
-			rc[1]= FTOCHAR(rf[1]);
-			rc[2]= FTOCHAR(rf[2]);
-			rc[3]= FTOCHAR(rf[3]);
-		}
-		rectf+= 4*row_w;
-	}
+	if (gamma_correct) {
+		floatbuf_to_srgb_byte(rectf, rect32, 0, img_w, 0, img_h, img_w);
+	} else {
+		floatbuf_to_byte(rectf, rect32, 0, img_w, 0, img_h, img_w);
+ 	}
 	
 	glaDrawPixelsSafe(fx, fy, img_w, img_h, img_w, GL_RGBA, GL_UNSIGNED_BYTE, rect32);
 
@@ -855,4 +849,3 @@ void bglFlush(void)
 #endif
 }
 
-
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index 07aaf0f9b58..812c9f11069 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -41,6 +41,7 @@
 #include "DNA_scene_types.h"
 
 #include "BKE_blender.h"
+#include "BKE_colortools.h"
 #include "BKE_context.h"
 #include "BKE_customdata.h"
 #include "BKE_global.h"
@@ -2575,21 +2576,46 @@ static void image_rect_update(void *rjv, RenderResult *rr, volatile rcti *renrec
 	rectf+= 4*(rr->rectx*ymin + xmin);
 	rectc= (char *)(ibuf->rect + ibuf->x*rymin + rxmin);
 
-	for(y1= 0; y1<ymax; y1++) {
-		float *rf= rectf;
-		char *rc= rectc;
-		
-		/* XXX temp. because crop offset */
-		if( rectc >= (char *)(ibuf->rect)) {
-			for(x1= 0; x1<xmax; x1++, rf += 4, rc+=4) {
-				rc[0]= FTOCHAR(rf[0]);
-				rc[1]= FTOCHAR(rf[1]);
-				rc[2]= FTOCHAR(rf[2]);
-				rc[3]= FTOCHAR(rf[3]);
+	/* XXX make nice consistent functions for this */
+	if (rj->scene->r.color_mgt_flag & R_COLOR_MANAGEMENT) {
+		for(y1= 0; y1<ymax; y1++) {
+			float *rf= rectf;
+			float srgb[3];
+			char *rc= rectc;
+			
+			/* XXX temp. because crop offset */
+			if( rectc >= (char *)(ibuf->rect)) {
+				for(x1= 0; x1<xmax; x1++, rf += 4, rc+=4) {
+					srgb[0]= linearrgb_to_srgb(rf[0]);
+					srgb[1]= linearrgb_to_srgb(rf[1]);
+					srgb[2]= linearrgb_to_srgb(rf[2]);
+
+					rc[0]= FTOCHAR(srgb[0]);
+					rc[1]= FTOCHAR(srgb[1]);
+					rc[2]= FTOCHAR(srgb[2]);
+					rc[3]= FTOCHAR(rf[3]);
+				}
+			}
+			rectf += 4*rr->rectx;
+			rectc += 4*ibuf->x;
+		}
+	} else {
+		for(y1= 0; y1<ymax; y1++) {
+			float *rf= rectf;
+			char *rc= rectc;
+			
+			/* XXX temp. because crop offset */
+			if( rectc >= (char *)(ibuf->rect)) {
+				for(x1= 0; x1<xmax; x1++, rf += 4, rc+=4) {
+					rc[0]= FTOCHAR(rf[0]);
+					rc[1]= FTOCHAR(rf[1]);
+					rc[2]= FTOCHAR(rf[2]);
+					rc[3]= FTOCHAR(rf[3]);
+				}
 			}
+			rectf += 4*rr->rectx;
+			rectc += 4*ibuf->x;
 		}
-		rectf += 4*rr->rectx;
-		rectc += 4*ibuf->x;
 	}
 	
 	/* make jobs timer to send notifier */