thumbnail: fix embedded ICC profile conversion (#3027)

libvips/resample/thumbnail.c

@@ -859,20 +859,37 @@ vips_thumbnail_build( VipsObject *object )
 		in = t[7];
 	}
 	else if( thumbnail->export_profile ) {
-		/* We are in one of the resize space (sRGB, scRGB, B_W, GREY16, 
-		 * etc.) and we have an export profile. Go to PCS, then export.
+		/* If there's some kind of import profile, we can transform to
+		 * the output. Otherwise, we are in one of the resize space
+		 * (sRGB, scRGB, B_W, GREY16, etc.) and need to go to PCS,
+		 * then export.
 		 */
-		g_info( "exporting with %s", 
-			thumbnail->export_profile ); 
-		if( vips_colourspace( in, &t[7], 
-			VIPS_INTERPRETATION_XYZ, NULL ) || 
-			vips_icc_export( t[7], &t[10], 
-				"output_profile", 
-					thumbnail->export_profile,
+		if( thumbnail->import_profile ||
+			vips_image_get_typeof( in, VIPS_META_ICC_NAME ) ) {
+			g_info( "transforming with supplied profiles" ); 
+			if( vips_icc_transform( in, &t[7], 
+				thumbnail->export_profile,
+				"input_profile", thumbnail->import_profile,
 				"intent", thumbnail->intent,
-				NULL ) )  
-			return( -1 ); 
-		in = t[10];
+				"embedded", TRUE,
+				NULL ) ) 
+				return( -1 );
+
+			in = t[7];
+		}
+		else {
+			g_info( "exporting with %s", 
+				thumbnail->export_profile ); 
+			if( vips_colourspace( in, &t[7], 
+				VIPS_INTERPRETATION_XYZ, NULL ) || 
+				vips_icc_export( t[7], &t[10], 
+					"output_profile", 
+						thumbnail->export_profile,
+					"intent", thumbnail->intent,
+					NULL ) )  
+				return( -1 ); 
+			in = t[10];
+		}
 	}
 	else {
 		/* We are in one of the resize spaces and there's no export

test/test-suite/helpers/helpers.py

@@ -9,6 +9,7 @@ import pyvips
 
 IMAGES = os.path.join(os.path.dirname(__file__), os.pardir, 'images')
 JPEG_FILE = os.path.join(IMAGES, "sample.jpg")
+JPEG_FILE_XYB = os.path.join(IMAGES, "sample-xyb.jpg")
 TRUNCATED_FILE = os.path.join(IMAGES, "truncated.jpg")
 SRGB_FILE = os.path.join(IMAGES, "sRGB.icm")
 MATLAB_FILE = os.path.join(IMAGES, "sample.mat")

test/test-suite/test_foreign.py

@@ -1395,14 +1395,12 @@ class TestForeign:
 
         # scrgb mode
         scrgb = self.colour.colourspace("scrgb")
-        no_profile.remove("icc-profile-data")
         self.save_load_buffer("jxlsave_buffer", "jxlload_buffer",
                               scrgb, 120)
 
         # scrgb mode, no profile
         scrgb_no_profile = scrgb.copy()
         scrgb_no_profile.remove("icc-profile-data")
-        no_profile.remove("icc-profile-data")
         self.save_load_buffer("jxlsave_buffer", "jxlload_buffer",
                               scrgb_no_profile, 120)
 

test/test-suite/test_resample.py

@@ -2,8 +2,8 @@
 import pytest
 
 import pyvips
-from helpers import JPEG_FILE, OME_FILE, HEIC_FILE, TIF_FILE, all_formats, \
-    have, RGBA_FILE, RGBA_CORRECT_FILE, AVIF_FILE
+from helpers import JPEG_FILE, JPEG_FILE_XYB, OME_FILE, HEIC_FILE, TIF_FILE, \
+    all_formats, have, RGBA_FILE, RGBA_CORRECT_FILE, AVIF_FILE
 
 
 # Run a function expecting a complex image on a two-band image
@@ -229,6 +229,21 @@ class TestResample:
             assert thumb.width < thumb.height
             assert thumb.height == 100
 
+    @pytest.mark.skipif(not pyvips.at_least_libvips(8, 5),
+                        reason="requires libvips >= 8.5")
+    def test_thumbnail_icc(self):
+        im = pyvips.Image.thumbnail(JPEG_FILE_XYB, 442, export_profile="srgb", intent="perceptual")
+
+        assert im.width == 290
+        assert im.height == 442
+        assert im.bands == 3
+        assert im.bands == 3
+
+        # the colour distance should not deviate too much
+        # (i.e. the embedded profile should not be ignored)
+        im_orig = pyvips.Image.new_from_file(JPEG_FILE)
+        assert im_orig.de00(im).max() < 10
+
     def test_similarity(self):
         im = pyvips.Image.new_from_file(JPEG_FILE)
         im2 = im.similarity(angle=90)