[qcms] Update primaries used to build internal sRGB profile

third_party/qcms/src/iccread.c

 /* vim: set ts=8 sw=8 noexpandtab: */
 //  qcms
 //  Copyright (C) 2009 Mozilla Foundation
 //  Copyright (C) 1998-2007 Marti Maria
 //
 // Permission is hereby granted, free of charge, to any person obtaining 
 // a copy of this software and associated documentation files (the "Software"), 
 // to deal in the Software without restriction, including without limitation 
 // the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 // and/or sell copies of the Software, and to permit persons to whom the Software 
@@ skipping 1220 matching lines @@
         profile->color_space = RGB_SIGNATURE;
         profile->pcs = XYZ_SIGNATURE;
         return profile;
 }
 
 /* from lcms: cmsWhitePointFromTemp */
 /* tempK must be >= 4000. and <= 25000.
  * Invalid values of tempK will return
  * (x,y,Y) = (-1.0, -1.0, -1.0)
  * similar to argyll: icx_DTEMP2XYZ() */
-static qcms_CIE_xyY white_point_from_temp(int temp_K)
+qcms_CIE_xyY white_point_from_temp(int temp_K)
 {
         qcms_CIE_xyY white_point;
         double x, y;
         double T, T2, T3;
         // double M1, M2;
 
         // No optimization provided.
         T = temp_K;
         T2 = T*T;            // Square
         T3 = T2*T;           // Cube
@@ skipping 32 matching lines @@
         white_point.Y = 1.0;
 
         return white_point;
 }
 
 qcms_profile* qcms_profile_sRGB(void)
 {
         qcms_profile *profile;
         uint16_t *table;
 
-        qcms_CIE_xyYTRIPLE Rec709Primaries = {
-                {0.6400, 0.3300, 1.0},
-                {0.3000, 0.6000, 1.0},
-                {0.1500, 0.0600, 1.0}
+        // Standard Illuminant D65 in XYZ coordinates, which is the standard
+        // sRGB IEC61966-2.1 / Rec.709 profile reference media white point.
+        struct XYZNumber D65 = {
+                0xf351, 0x10000, 0x116cc // ( 0.950455, 1.000000, 1.089050 )
         };
-        qcms_CIE_xyY D65;
 
-        D65 = white_point_from_temp(6504);
+        // sRGB IEC61966-2.1 / Rec.709 color profile primaries, chromatically
+        // adapted (via Bradford procedures) to the ICC PCS white point, D50.
+        s15Fixed16Number primaries[3][3] = {
+                { 0x06fa2, 0x06299, 0x024a0 }, // ( 0.436066, 0.385147, 0.143066 )
+                { 0x038f5, 0x0b785, 0x00f84 }, // ( 0.222488, 0.716873, 0.060608 )
+                { 0x00390, 0x018da, 0x0b6cf }, // ( 0.013916, 0.097076, 0.714096 )
+        };

[Noel Gordon, 2016/03/14 21:31:37]

What were the values produced for this matrix prior to this change?

[Noel Gordon, 2016/03/14 22:34:07]

And how does everything compare to the matrix published in the standard? [1].

[1] https://www.w3.org/Graphics/Color/srgb

But based on the note attached to https://www.w3.org/Graphics/Color/sRGB.html
(at the top of the page), one has to question the numerical accuracy of those
tristimulus primaries.

Indeed, "Would the real sRGB profile please stand up?" Refer to article with
name,
http://ninedegreesbelow.com/photography/srgb-profile-comparison.html#conclusion

So let's not submit until we've sorted the about out, and can explain the why
our munsell chart layout tests have regressed.

[radu.velea, 2016/03/15 14:50:27]

Original values:
0x06f94	0x062a4	0x0249c
0x038ed	0x0b78f	0x00f82
0x00390	0x018dd	0x0b6be

 
         table = build_sRGB_gamma_table(1024);
 
         if (!table)
                 return NO_MEM_PROFILE;
 
-        profile = qcms_profile_create_rgb_with_table(D65, Rec709Primaries, table, 1024);
-        if (profile)
-                strcpy(profile->description, "sRGB IEC61966-2.1");
+        profile = qcms_profile_create();
+
+        if (!profile) {
+                free(table);
+                return NO_MEM_PROFILE;
+        }
+
+        profile->redTRC = curve_from_table(table, 1024);
+        profile->blueTRC = curve_from_table(table, 1024);
+        profile->greenTRC = curve_from_table(table, 1024);
+
+        if (!profile->redTRC || !profile->blueTRC || !profile->greenTRC) {
+                free(table);
+                qcms_profile_release(profile);
+                return NO_MEM_PROFILE;
+        }
+
+        profile->redColorant.X = primaries[0][0];
+        profile->redColorant.Y = primaries[1][0];
+        profile->redColorant.Z = primaries[2][0];
+
+        profile->greenColorant.X = primaries[0][1];
+        profile->greenColorant.Y = primaries[1][1];
+        profile->greenColorant.Z = primaries[2][1];
+
+        profile->blueColorant.X = primaries[0][2];
+        profile->blueColorant.Y = primaries[1][2];
+        profile->blueColorant.Z = primaries[2][2];
+
+        profile->mediaWhitePoint.X = D65.X;
+        profile->mediaWhitePoint.Y = D65.Y;
+        profile->mediaWhitePoint.Z = D65.Z;
+
+        profile->class = DISPLAY_DEVICE_PROFILE;
+        profile->rendering_intent = QCMS_INTENT_PERCEPTUAL;
+        profile->color_space = RGB_SIGNATURE;
+        profile->pcs = XYZ_SIGNATURE;
+
+        strcpy(profile->description, "sRGB IEC61966-2.1");
 
         free(table);
+
         return profile;
 }
 
 /* qcms_profile_from_memory does not hold a reference to the memory passed in */
 qcms_profile* qcms_profile_from_memory(const void *mem, size_t size)
 {
         uint32_t length;
         struct mem_source source;
         struct mem_source *src = &source;
         struct tag_index index;
@@ skipping 260 matching lines @@
 {
         qcms_profile *profile = NULL;
         FILE *file = _wfopen(path, L"rb");
         if (file) {
                 profile = qcms_profile_from_file(file);
                 fclose(file);
         }
         return profile;
 }
 #endif