Bug 756389 - Color-managing grayscale images

Support creating linear/sRGB-gamma variants of gray profiles and
rename gimp_color_profile_new_linear_rgb_from_color_profile() to
gimp_color_profile_new_linear_gamma_from_color_profile() because it's
not RGB-specific any longer.

Author: mitchfoo

app/core/gimpimage-convert-precision.c

@@ -173,7 +173,7 @@ gimp_image_convert_precision (GimpImage     *image,
       if (gimp_babl_format_get_linear (new_format))
         {
           new_profile =
-            gimp_color_profile_new_linear_rgb_from_color_profile (old_profile);
+            gimp_color_profile_new_linear_gamma_from_color_profile (old_profile);
         }
       else
         {

app/core/gimplayer.c

@@ -1136,7 +1136,7 @@ gimp_layer_convert_type (GimpDrawable      *drawable,
               if (gimp_babl_format_get_linear (new_format))
                 {
                   dest_profile =
-                    gimp_color_profile_new_linear_rgb_from_color_profile (src_profile);
+                    gimp_color_profile_new_linear_gamma_from_color_profile (src_profile);
                 }
               else
                 {

libgimpcolor/gimpcolor.def

@@ -44,9 +44,9 @@ EXPORTS
 	gimp_color_profile_new_from_file
 	gimp_color_profile_new_from_icc_profile
 	gimp_color_profile_new_from_lcms_profile
+	gimp_color_profile_new_linear_gamma_from_color_profile
 	gimp_color_profile_new_linear_gray
 	gimp_color_profile_new_linear_rgb
-	gimp_color_profile_new_linear_rgb_from_color_profile
 	gimp_color_profile_new_srgb
 	gimp_color_profile_new_srgb_gray
 	gimp_color_profile_new_srgb_gamma_from_color_profile

libgimpcolor/gimpcolorprofile.c

@@ -788,48 +788,35 @@ gimp_color_profile_new_from_color_profile (GimpColorProfile *profile,
 {
   GimpColorProfile *new_profile;
   cmsHPROFILE       target_profile;
-  GimpMatrix3       matrix;
-  cmsCIEXYZ         red;
-  cmsCIEXYZ         green;
-  cmsCIEXYZ         blue;
+  GimpMatrix3       matrix = { 0, };
   cmsCIEXYZ        *whitepoint;
   cmsToneCurve     *curve;
   const gchar      *model;
   gchar            *new_model;
 
   g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), NULL);
 
-  if (! gimp_color_profile_get_rgb_matrix_colorants (profile, &matrix))
-    return NULL;
+  if (gimp_color_profile_is_rgb (profile))
+    {
+      if (! gimp_color_profile_get_rgb_matrix_colorants (profile, &matrix))
+        return NULL;
+    }
+  else if (! gimp_color_profile_is_gray (profile))
+    {
+      return NULL;
+    }
 
   whitepoint = cmsReadTag (profile->priv->lcms_profile,
                            cmsSigMediaWhitePointTag);
 
-  red.X = matrix.coeff[0][0];
-  red.Y = matrix.coeff[0][1];
-  red.Z = matrix.coeff[0][2];
-
-  green.X = matrix.coeff[1][0];
-  green.Y = matrix.coeff[1][1];
-  green.Z = matrix.coeff[1][2];
-
-  blue.X = matrix.coeff[2][0];
-  blue.Y = matrix.coeff[2][1];
-  blue.Z = matrix.coeff[2][2];
-
   target_profile = cmsCreateProfilePlaceholder (0);
 
   cmsSetProfileVersion (target_profile, 4.3);
   cmsSetDeviceClass (target_profile, cmsSigDisplayClass);
-  cmsSetColorSpace (target_profile, cmsSigRgbData);
   cmsSetPCS (target_profile, cmsSigXYZData);
 
   cmsWriteTag (target_profile, cmsSigMediaWhitePointTag, whitepoint);
 
-  cmsWriteTag (target_profile, cmsSigRedColorantTag,   &red);
-  cmsWriteTag (target_profile, cmsSigGreenColorantTag, &green);
-  cmsWriteTag (target_profile, cmsSigBlueColorantTag,  &blue);
-
   if (linear)
     {
       /* linear light */
@@ -850,9 +837,40 @@ gimp_color_profile_new_from_color_profile (GimpColorProfile *profile,
                                   "sRGB gamma variant generated by GIMP");
     }
 
-  cmsWriteTag (target_profile, cmsSigRedTRCTag,   curve);
-  cmsWriteTag (target_profile, cmsSigGreenTRCTag, curve);
-  cmsWriteTag (target_profile, cmsSigBlueTRCTag,  curve);
+  if (gimp_color_profile_is_rgb (profile))
+    {
+      cmsCIEXYZ red;
+      cmsCIEXYZ green;
+      cmsCIEXYZ blue;
+
+      cmsSetColorSpace (target_profile, cmsSigRgbData);
+
+      red.X = matrix.coeff[0][0];
+      red.Y = matrix.coeff[0][1];
+      red.Z = matrix.coeff[0][2];
+
+      green.X = matrix.coeff[1][0];
+      green.Y = matrix.coeff[1][1];
+      green.Z = matrix.coeff[1][2];
+
+      blue.X = matrix.coeff[2][0];
+      blue.Y = matrix.coeff[2][1];
+      blue.Z = matrix.coeff[2][2];
+
+      cmsWriteTag (target_profile, cmsSigRedColorantTag,   &red);
+      cmsWriteTag (target_profile, cmsSigGreenColorantTag, &green);
+      cmsWriteTag (target_profile, cmsSigBlueColorantTag,  &blue);
+
+      cmsWriteTag (target_profile, cmsSigRedTRCTag,   curve);
+      cmsWriteTag (target_profile, cmsSigGreenTRCTag, curve);
+      cmsWriteTag (target_profile, cmsSigBlueTRCTag,  curve);
+    }
+  else
+    {
+      cmsSetColorSpace (target_profile, cmsSigGrayData);
+
+      cmsWriteTag (target_profile, cmsSigGrayTRCTag, curve);
+    }
 
   cmsFreeToneCurve (curve);
 
@@ -906,7 +924,7 @@ gimp_color_profile_new_srgb_gamma_from_color_profile (GimpColorProfile *profile)
 }
 
 /**
- * gimp_color_profile_new_linear_rgb_from_color_profile:
+ * gimp_color_profile_new_linear_gamma_from_color_profile:
  * @profile: a #GimpColorProfile
  *
  * This function creates a new RGB #GimpColorProfile with a linear TRC
@@ -918,7 +936,7 @@ gimp_color_profile_new_srgb_gamma_from_color_profile (GimpColorProfile *profile)
  * Since: 2.10
  **/
 GimpColorProfile *
-gimp_color_profile_new_linear_rgb_from_color_profile (GimpColorProfile *profile)
+gimp_color_profile_new_linear_gamma_from_color_profile (GimpColorProfile *profile)
 {
   g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), NULL);
 

libgimpcolor/gimpcolorprofile.h

@@ -72,9 +72,9 @@ GimpColorProfile * gimp_color_profile_new_srgb_gray         (void);
 GimpColorProfile * gimp_color_profile_new_linear_gray       (void);
 
 GimpColorProfile *
-       gimp_color_profile_new_srgb_gamma_from_color_profile (GimpColorProfile  *profile);
+     gimp_color_profile_new_srgb_gamma_from_color_profile   (GimpColorProfile  *profile);
 GimpColorProfile *
-       gimp_color_profile_new_linear_rgb_from_color_profile (GimpColorProfile  *profile);
+     gimp_color_profile_new_linear_gamma_from_color_profile (GimpColorProfile  *profile);
 
 GimpColorProfile * gimp_color_profile_new_from_file         (GFile             *file,
                                                              GError           **error);