fix test suite

- CMYK2XYZ and back now support extra alpha bands
- test suite tests CMYK conversions
- a small bug fixed too

libvips/colour/CMYK2XYZ.c

@@ -92,8 +92,6 @@ vips__CMYK2XYZ_get_fallback_profile( size_t *length )
 }
 
 /* Shared with XYZ2CMYK.c.
- *
- * FIXME ... should this remove and replace a non-CMYK profile?
  */
 int
 vips_CMYK2XYZ_set_fallback_profile( VipsImage *image )
@@ -101,8 +99,11 @@ vips_CMYK2XYZ_set_fallback_profile( VipsImage *image )
 	size_t data_length;
 	unsigned char *data;
 
+	/* Already a profile? Do nothing. We could remove and replace non-CMYK
+	 * profiles I guess.
+	 */
 	if( vips_image_get_typeof( image, VIPS_META_ICC_NAME ) )
-		return( -1 );
+		return( 0 );
 
 	if( !(data = vips__CMYK2XYZ_get_fallback_profile( &data_length )) )
 		return( -1 );
@@ -113,11 +114,22 @@ vips_CMYK2XYZ_set_fallback_profile( VipsImage *image )
 	return( 0 );
 }
 
+/* Our actual processing, as a VipsColourTransformFn.
+ */
+static int
+vips_CMYK2XYZ_process( VipsImage *in, VipsImage **out, ... )
+{
+	return( vips_icc_import( in, out,
+		"embedded", TRUE,
+		"pcs", VIPS_PCS_XYZ,
+		NULL ) );
+}
+
 static int
 vips_CMYK2XYZ_build( VipsObject *object )
 {
 	VipsCMYK2XYZ *CMYK2XYZ = (VipsCMYK2XYZ *) object;
-	VipsImage **t = (VipsImage **) vips_object_local_array( object, 7 );
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
 
 	VipsImage *out; 
 
@@ -129,10 +141,8 @@ vips_CMYK2XYZ_build( VipsObject *object )
 
 	if( vips_copy( CMYK2XYZ->in, &t[0], NULL ) ||
 		vips_CMYK2XYZ_set_fallback_profile( t[0] ) ||
-		vips_icc_import( t[0], &t[1],
-			"embedded", TRUE,
-			"pcs", VIPS_PCS_XYZ,
-			NULL ) ||
+		vips__colourspace_process_n( "CMYK2XYZ", 
+			t[0], &t[1], 4, vips_CMYK2XYZ_process ) ||
 		vips_image_write( t[1], out ) )
 		return( -1 );
 

libvips/colour/XYZ2CMYK.c

@@ -59,11 +59,21 @@ typedef VipsColourCodeClass VipsXYZ2CMYKClass;
 
 G_DEFINE_TYPE( VipsXYZ2CMYK, vips_XYZ2CMYK, VIPS_TYPE_OPERATION );
 
+/* Our actual processing, as a VipsColourTransformFn.
+ */
+static int
+vips_XYZ2CMYK_process( VipsImage *in, VipsImage **out, ... )
+{
+	return( vips_icc_export( in, out,
+		"pcs", VIPS_PCS_XYZ,
+		NULL ) );
+}
+
 static int
 vips_XYZ2CMYK_build( VipsObject *object )
 {
 	VipsXYZ2CMYK *XYZ2CMYK = (VipsXYZ2CMYK *) object;
-	VipsImage **t = (VipsImage **) vips_object_local_array( object, 7 );
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
 
 	VipsImage *out; 
 
@@ -75,9 +85,8 @@ vips_XYZ2CMYK_build( VipsObject *object )
 
 	if( vips_copy( XYZ2CMYK->in, &t[0], NULL ) ||
 		vips_CMYK2XYZ_set_fallback_profile( t[0] ) ||
-		vips_icc_export( t[0], &t[1],
-			"pcs", VIPS_PCS_XYZ,
-			NULL ) ||
+		vips__colourspace_process_n( "XYZ2CMYK", 
+			t[0], &t[1], 3, vips_XYZ2CMYK_process ) ||
 		vips_image_write( t[1], out ) )
 		return( -1 );
 

libvips/colour/colourspace.c

@@ -68,10 +68,6 @@
 
 #include "pcolour.h"
 
-/* A colour-transforming function.
- */
-typedef int (*VipsColourTransformFn)( VipsImage *in, VipsImage **out, ... );
-
 static int
 vips_scRGB2RGB16( VipsImage *in, VipsImage **out, ... )
 {
@@ -113,10 +109,12 @@ vips_sRGB2RGB16( VipsImage *in, VipsImage **out, ... )
 }
 
 /* Process the first @n bands with @fn, detach and reattach remaining bands.
+ *
+ * Also used by CMYK2XYZ and XYZ2CMYK.
  */
-static int
-vips_process_n( const char *domain, VipsImage *in, VipsImage **out, 
-	int n, VipsColourTransformFn fn )
+int
+vips__colourspace_process_n( const char *domain, 
+	VipsImage *in, VipsImage **out, int n, VipsColourTransformFn fn )
 {
 	if( in->Bands > n ) {
 		VipsImage *scope = vips_image_new();
@@ -168,7 +166,8 @@ vips_BW2sRGB_op( VipsImage *in, VipsImage **out, ... )
 static int
 vips_BW2sRGB( VipsImage *in, VipsImage **out, ... )
 {
-	if( vips_process_n( "BW2sRGB", in, out, 1, vips_BW2sRGB_op ) )
+	if( vips__colourspace_process_n( "BW2sRGB", 
+		in, out, 1, vips_BW2sRGB_op ) )
 		return( -1 );
 	(*out)->Type = VIPS_INTERPRETATION_sRGB;
 
@@ -178,7 +177,8 @@ vips_BW2sRGB( VipsImage *in, VipsImage **out, ... )
 static int
 vips_GREY162RGB16( VipsImage *in, VipsImage **out, ... )
 {
-	if( vips_process_n( "GREY162RGB16", in, out, 1, vips_BW2sRGB_op ) )
+	if( vips__colourspace_process_n( "GREY162RGB16", 
+		in, out, 1, vips_BW2sRGB_op ) )
 		return( -1 );
 	(*out)->Type = VIPS_INTERPRETATION_RGB16;
 

libvips/colour/pcolour.h

@@ -218,6 +218,13 @@ void vips_col_make_tables_RGB_16( void );
 
 int vips_CMYK2XYZ_set_fallback_profile( VipsImage *image );
 
+/* A colour-transforming function.
+ */
+typedef int (*VipsColourTransformFn)( VipsImage *in, VipsImage **out, ... );
+
+int vips__colourspace_process_n( const char *domain, 
+	VipsImage *in, VipsImage **out, int n, VipsColourTransformFn fn );
+
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/

test/test-suite/helpers/helpers.py

@@ -49,17 +49,18 @@ colour_colourspaces = [pyvips.Interpretation.XYZ,
                        pyvips.Interpretation.LCH,
                        pyvips.Interpretation.CMC,
                        pyvips.Interpretation.LABS,
-                       pyvips.Interpretation.CMYK,
                        pyvips.Interpretation.SCRGB,
                        pyvips.Interpretation.HSV,
                        pyvips.Interpretation.SRGB,
                        pyvips.Interpretation.YXY]
+cmyk_colourspaces = [pyvips.Interpretation.CMYK]
 coded_colourspaces = [pyvips.Interpretation.LABQ]
 mono_colourspaces = [pyvips.Interpretation.B_W]
 sixteenbit_colourspaces = [pyvips.Interpretation.GREY16,
                            pyvips.Interpretation.RGB16]
 all_colourspaces = colour_colourspaces + mono_colourspaces + \
-                   coded_colourspaces + sixteenbit_colourspaces
+                   coded_colourspaces + sixteenbit_colourspaces + \
+                   cmyk_colourspaces
 
 max_value = {pyvips.BandFormat.UCHAR: 0xff,
              pyvips.BandFormat.USHORT: 0xffff,

test/test-suite/test_colour.py

@@ -71,6 +71,19 @@ class TestColour:
                 # but 8-bit we should hit exactly
                 assert abs(after - before) < 1
 
+        # we should be able to go from cmyk to any 3-band space and back again,
+        # approximately
+        cmyk = test.colourspace(pyvips.Interpretation.CMYK)
+        for end in colour_colourspaces:
+            im = cmyk.colourspace(end)
+            im2 = im.colourspace(pyvips.Interpretation.CMYK)
+
+            before = cmyk(10, 10)
+            after = im2(10, 10)
+
+            assert_almost_equal_objects(before, after, threshold=10)
+
+
     # test results from Bruce Lindbloom's calculator:
     # http://www.brucelindbloom.com
     def test_dE00(self):