fix profile handling in XYZ2scRGB

see

https://github.com/lovell/sharp/issues/125

ChangeLog

@@ -1,6 +1,7 @@
 27/10/14 started 7.40.12
 - better tiff detection (Lovell)
 - fix memleak in sharpen (Lovell)
+- fix profile handling in XYZ2scRGB, thanks Lovell
 
 8/10/14 started 7.40.11
 - rework extra band handling for colour functions

libvips/colour/XYZ2scRGB.c

@@ -4,6 +4,8 @@
  * 	- from Yxy2XYZ.c
  * 1/7/13
  * 	- remove any ICC profile
+ * 25/11/14
+ * 	- oh argh, revert the above
  */
 
 /*
@@ -50,20 +52,21 @@ typedef VipsColourSpaceClass VipsXYZ2scRGBClass;
 
 G_DEFINE_TYPE( VipsXYZ2scRGB, vips_XYZ2scRGB, VIPS_TYPE_COLOUR_SPACE );
 
-static int
-vips_XYZ2scRGB_build( VipsObject *object )
-{
-	if( VIPS_OBJECT_CLASS( vips_XYZ2scRGB_parent_class )->build( object ) )
-		return( -1 );
+/* We used to have the comment:
 
-	/* We've converted to sRGB without a profile. We must remove any ICC
+	 * We've converted to sRGB without a profile. We must remove any ICC
 	 * profile left over from import or there will be a mismatch between
 	 * pixel values and the attached profile. 
-	 */
-	vips_image_remove( VIPS_COLOUR( object )->out, VIPS_META_ICC_NAME );
 
-	return( 0 );
-}
+   But this isn't right, we often call things sRGB that we know are not true 
+   sRGB, for example:
+
+   	vips sharpen k2.jpg x.jpg
+
+   sharpen will treat k2 as being in sRGB space even if that image has a 
+   profile. If we drop the profile, x.jpg is suddenly untagged.
+
+ */
 
 void
 vips_XYZ2scRGB_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
@@ -100,7 +103,6 @@ vips_XYZ2scRGB_class_init( VipsXYZ2scRGBClass *class )
 
 	object_class->nickname = "XYZ2scRGB";
 	object_class->description = _( "transform XYZ to scRGB" );
-	object_class->build = vips_XYZ2scRGB_build;
 
 	colour_class->process_line = vips_XYZ2scRGB_line;
 }
@@ -117,8 +119,9 @@ vips_XYZ2scRGB_init( VipsXYZ2scRGB *XYZ2scRGB )
  * vips_XYZ2scRGB:
  * @in: input image
  * @out: output image
+ * @...: %NULL-terminated list of optional named arguments
  *
- * Turn XYZ to Yxy.
+ * Turn XYZ to scRGB.
  *
  * Returns: 0 on success, -1 on error
  */