add Image#TransformICCProfileWithFallback (#373)

* add Image#TransformICCProfileWithFallback

This fixes #314.

* add tests for Image#TransformICCProfileWithFallback()

* remove optimization from TransformICCProfileWithFallback

The code tried to avoid a no-op when transforming from profile A to profile A.
But it did not taken into account that the result should always contain
an ICC profile and that the no-op actually changes the image by applying
the target profile without modifying anything else.

vips/image.go

@@ -1372,19 +1372,15 @@ func (r *ImageRef) RemoveICCProfile() error {
 	return nil
 }
 
-// TransformICCProfile transforms from the embedded ICC profile of the image to the icc profile at the given path.
-func (r *ImageRef) TransformICCProfile(outputProfilePath string) error {
-	// If the image has an embedded profile, that will be used and the input profile ignored.
-	// Otherwise, images without an input profile are assumed to use a standard RGB profile.
-	embedded := r.HasICCProfile()
-	inputProfile := SRGBIEC6196621ICCProfilePath
-
+// TransformICCProfileWithFallback transforms from the embedded ICC profile of the image to the ICC profile at the given path.
+// The fallback ICC profile is used if the image does not have an embedded ICC profile.
+func (r *ImageRef) TransformICCProfileWithFallback(targetProfilePath, fallbackProfilePath string) error {
 	depth := 16
 	if r.BandFormat() == BandFormatUchar || r.BandFormat() == BandFormatChar || r.BandFormat() == BandFormatNotSet {
 		depth = 8
 	}
 
-	out, err := vipsICCTransform(r.image, outputProfilePath, inputProfile, IntentPerceptual, depth, embedded)
+	out, err := vipsICCTransform(r.image, targetProfilePath, fallbackProfilePath, IntentPerceptual, depth, true)
 	if err != nil {
 		govipsLog("govips", LogLevelError, fmt.Sprintf("failed to do icc transform: %v", err.Error()))
 		return err
@@ -1394,13 +1390,18 @@ func (r *ImageRef) TransformICCProfile(outputProfilePath string) error {
 	return nil
 }
 
+// TransformICCProfile transforms from the embedded ICC profile of the image to the icc profile at the given path.
+func (r *ImageRef) TransformICCProfile(outputProfilePath string) error {
+	return r.TransformICCProfileWithFallback(outputProfilePath, SRGBIEC6196621ICCProfilePath)
+}
+
 // OptimizeICCProfile optimizes the ICC color profile of the image.
 // For two color channel images, it sets a grayscale profile.
 // For color images, it sets a CMYK or non-CMYK profile based on the image metadata.
 func (r *ImageRef) OptimizeICCProfile() error {
 	inputProfile := r.determineInputICCProfile()
 	if !r.HasICCProfile() && (inputProfile == "") {
-		//No embedded ICC profile in the input image and no input profile determined, nothing to do.
+		// No embedded ICC profile in the input image and no input profile determined, nothing to do.
 		return nil
 	}
 

vips/image_golden_test.go

@@ -126,6 +126,57 @@ func TestImage_TransformICCProfile_RGB_Embedded(t *testing.T) {
 		}, nil)
 }
 
+func TestImage_TransformICCProfileWithFallback(t *testing.T) {
+	t.Run("RGB source without ICC", func(t *testing.T) {
+		goldenTest(t, resources+"jpg-24bit-rgb-no-icc.jpg",
+			func(img *ImageRef) error {
+				return img.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, resources+"adobe-rgb.icc")
+			},
+			func(result *ImageRef) {
+				assert.True(t, result.HasICCProfile())
+				iccProfileData := result.GetICCProfile()
+				assert.Greater(t, len(iccProfileData), 0)
+				assert.Equal(t, InterpretationSRGB, result.Interpretation())
+			}, nil)
+	})
+	t.Run("RGB source with ICC", func(t *testing.T) {
+		goldenTest(t, resources+"jpg-24bit-icc-adobe-rgb.jpg",
+			func(img *ImageRef) error {
+				return img.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, SRGBV2MicroICCProfilePath)
+			},
+			func(result *ImageRef) {
+				assert.True(t, result.HasICCProfile())
+				iccProfileData := result.GetICCProfile()
+				assert.Greater(t, len(iccProfileData), 0)
+				assert.Equal(t, InterpretationSRGB, result.Interpretation())
+			}, nil)
+	})
+	t.Run("CMYK source without ICC", func(t *testing.T) {
+		goldenTest(t, resources+"jpg-32bit-cmyk-no-icc.jpg",
+			func(img *ImageRef) error {
+				return img.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, "cmyk")
+			},
+			func(result *ImageRef) {
+				assert.True(t, result.HasICCProfile())
+				iccProfileData := result.GetICCProfile()
+				assert.Greater(t, len(iccProfileData), 0)
+				assert.Equal(t, InterpretationSRGB, result.Interpretation())
+			}, nil)
+	})
+	t.Run("CMYK source with ICC", func(t *testing.T) {
+		goldenTest(t, resources+"jpg-32bit-cmyk-icc-swop.jpg",
+			func(img *ImageRef) error {
+				return img.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, "cmyk")
+			},
+			func(result *ImageRef) {
+				assert.True(t, result.HasICCProfile())
+				iccProfileData := result.GetICCProfile()
+				assert.Greater(t, len(iccProfileData), 0)
+				assert.Equal(t, InterpretationSRGB, result.Interpretation())
+			}, nil)
+	})
+}
+
 func TestImage_OptimizeICCProfile_CMYK(t *testing.T) {
 	goldenTest(t, resources+"jpg-32bit-cmyk-icc-swop.jpg",
 		func(img *ImageRef) error {
@@ -319,7 +370,7 @@ func TestImage_AutoRotate_6__jpeg_to_webp(t *testing.T) {
 			// expected should be 1
 			// Known issue: libvips does not write EXIF into WebP:
 			// https://github.com/libvips/libvips/pull/1745
-			//assert.Equal(t, 0, result.Orientation())
+			// assert.Equal(t, 0, result.Orientation())
 		},
 		exportWebp(nil),
 	)
@@ -366,7 +417,7 @@ func TestImage_TIF_16_Bit_To_AVIF_12_Bit(t *testing.T) {
 
 func TestImage_Sharpen_24bit_Alpha(t *testing.T) {
 	goldenTest(t, resources+"png-24bit+alpha.png", func(img *ImageRef) error {
-		//usm_0.66_1.00_0.01
+		// usm_0.66_1.00_0.01
 		sigma := 1 + (0.66 / 2)
 		x1 := 0.01 * 100
 		m2 := 1.0
@@ -377,7 +428,7 @@ func TestImage_Sharpen_24bit_Alpha(t *testing.T) {
 
 func TestImage_Sharpen_8bit_Alpha(t *testing.T) {
 	goldenTest(t, resources+"png-8bit+alpha.png", func(img *ImageRef) error {
-		//usm_0.66_1.00_0.01
+		// usm_0.66_1.00_0.01
 		sigma := 1 + (0.66 / 2)
 		x1 := 0.01 * 100
 		m2 := 1.0

vips/image_test.go

@@ -469,6 +469,36 @@ func TestImageRef_TransformICCProfile(t *testing.T) {
 	assert.True(t, image.HasICCProfile())
 }
 
+func TestImageRef_TransformICCProfileWithFallback(t *testing.T) {
+	Startup(nil)
+
+	t.Run("source with ICC", func(t *testing.T) {
+		image, err := NewImageFromFile(resources + "jpg-24bit-icc-adobe-rgb.jpg")
+		require.NoError(t, err)
+
+		require.True(t, image.HasIPTC())
+		require.True(t, image.HasICCProfile())
+
+		err = image.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, SRGBV2MicroICCProfilePath)
+		require.NoError(t, err)
+
+		assert.True(t, image.HasIPTC())
+		assert.True(t, image.HasICCProfile())
+	})
+
+	t.Run("source without ICC", func(t *testing.T) {
+		image, err := NewImageFromFile(resources + "jpg-24bit.jpg")
+		require.NoError(t, err)
+
+		require.False(t, image.HasICCProfile())
+
+		err = image.TransformICCProfileWithFallback(SRGBIEC6196621ICCProfilePath, SRGBV2MicroICCProfilePath)
+		require.NoError(t, err)
+
+		assert.True(t, image.HasICCProfile())
+	})
+}
+
 func TestImageRef_Close(t *testing.T) {
 	Startup(nil)
 
@@ -661,7 +691,7 @@ func TestImageRef_CompositeMulti(t *testing.T) {
 		image, err := NewImageFromFile(resources + uri)
 		require.NoError(t, err)
 
-		//add offset test
+		// add offset test
 		images[i] = &ImageComposite{image, BlendModeOver, (i + 1) * 20, (i + 2) * 20}
 	}