#621 Don't add ICC profile for default gray images

(cherry picked from commit 105a1ee466f07d6b3397eac61f17543bdb26fb93)

imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/color/ColorSpaces.java

@@ -239,6 +239,7 @@ public final class ColorSpaces {
      * @return {@code true} if {@code profile} is equal to the default sRGB profile.
      * @throws IllegalArgumentException if {@code profile} is {@code null}
      *
+     * @see java.awt.color.ColorSpace#CS_sRGB
      * @see java.awt.color.ColorSpace#isCS_sRGB()
      */
     public static boolean isCS_sRGB(final ICC_Profile profile) {
@@ -247,6 +248,21 @@ public final class ColorSpaces {
         return profile.getColorSpaceType() == ColorSpace.TYPE_RGB && Arrays.equals(getProfileHeaderWithProfileId(profile), sRGB.header);
     }
 
+    /**
+     * Tests whether an ICC color profile is equal to the default GRAY profile.
+     *
+     * @param profile the ICC profile to test. May not be {@code null}.
+     * @return {@code true} if {@code profile} is equal to the default GRAY profile.
+     * @throws IllegalArgumentException if {@code profile} is {@code null}
+     *
+     * @see java.awt.color.ColorSpace#CS_GRAY
+     */
+    public static boolean isCS_GRAY(final ICC_Profile profile) {
+        Validate.notNull(profile, "profile");
+
+        return profile.getColorSpaceType() == ColorSpace.TYPE_GRAY && Arrays.equals(getProfileHeaderWithProfileId(profile), GRAY.header);
+    }
+
     /**
      * Tests whether an ICC color profile is known to cause problems for {@link java.awt.image.ColorConvertOp}.
      * <p>

imageio/imageio-core/src/test/java/com/twelvemonkeys/imageio/color/ColorSpacesTest.java

@@ -184,6 +184,24 @@ public class ColorSpacesTest {
         ColorSpaces.isCS_sRGB(null);
     }
 
+    @Test
+    public void testIsCS_GRAYTrue() {
+        assertTrue(ColorSpaces.isCS_GRAY(ICC_Profile.getInstance(ColorSpace.CS_GRAY)));
+    }
+
+    @Test
+    public void testIsCS_GRAYFalse() {
+        assertFalse(ColorSpaces.isCS_GRAY(ICC_Profile.getInstance(ColorSpace.CS_sRGB)));
+        assertFalse(ColorSpaces.isCS_GRAY(ICC_Profile.getInstance(ColorSpace.CS_LINEAR_RGB)));
+        assertFalse(ColorSpaces.isCS_GRAY(ICC_Profile.getInstance(ColorSpace.CS_CIEXYZ)));
+        assertFalse(ColorSpaces.isCS_GRAY(ICC_Profile.getInstance(ColorSpace.CS_PYCC)));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testIsCS_GRAYNull() {
+        ColorSpaces.isCS_GRAY(null);
+    }
+
     @Test
     public void testEqualHeadersDifferentProfile() throws IOException {
         // These profiles are extracted from various JPEGs, and have the exact same profile header...

imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/TIFFImageWriter.java

@@ -32,6 +32,7 @@ package com.twelvemonkeys.imageio.plugins.tiff;
 
 import com.twelvemonkeys.image.ImageUtil;
 import com.twelvemonkeys.imageio.ImageWriterBase;
+import com.twelvemonkeys.imageio.color.ColorSpaces;
 import com.twelvemonkeys.imageio.metadata.Directory;
 import com.twelvemonkeys.imageio.metadata.Entry;
 import com.twelvemonkeys.imageio.metadata.tiff.Rational;
@@ -849,9 +850,11 @@ public final class TIFFImageWriter extends ImageWriterBase {
         else {
             entries.put(TIFF.TAG_SAMPLES_PER_PIXEL, new TIFFEntry(TIFF.TAG_SAMPLES_PER_PIXEL, numBands));
 
-            // Note: Assuming sRGB to be the default RGB interpretation
+            // Embed ICC profile if we have one that:
+            // * is not sRGB (assuming sRGB to be the default RGB interpretation), and
+            // * is not gray scale (assuming photometric either BlackIsZero or WhiteIsZero)
             ColorSpace colorSpace = colorModel.getColorSpace();
-            if (colorSpace instanceof ICC_ColorSpace && !colorSpace.isCS_sRGB()) {
+            if (colorSpace instanceof ICC_ColorSpace && !colorSpace.isCS_sRGB() && !ColorSpaces.isCS_GRAY(((ICC_ColorSpace) colorSpace).getProfile())) {
                 entries.put(TIFF.TAG_ICC_PROFILE, new TIFFEntry(TIFF.TAG_ICC_PROFILE, ((ICC_ColorSpace) colorSpace).getProfile().getData()));
             }
         }

imageio/imageio-tiff/src/test/java/com/twelvemonkeys/imageio/plugins/tiff/TIFFImageWriterTest.java

@@ -554,6 +554,28 @@ public class TIFFImageWriterTest extends ImageWriterAbstractTest<TIFFImageWriter
         }
     }
 
+    @Test
+    public void testWriteGrayNoProfile() throws IOException {
+        ImageWriter writer = createWriter();
+
+        FastByteArrayOutputStream bytes = new FastByteArrayOutputStream(512);
+
+        try (ImageOutputStream output = ImageIO.createImageOutputStream(bytes)) {
+            writer.setOutput(output);
+            writer.write(new BufferedImage(10, 10, BufferedImage.TYPE_BYTE_GRAY));
+        }
+
+        try (ImageInputStream input = ImageIO.createImageInputStream(bytes.createInputStream())) {
+            ImageReader reader = ImageIO.getImageReaders(input).next();
+            reader.setInput(input);
+
+            TIFFImageMetadata metadata = (TIFFImageMetadata) reader.getImageMetadata(0);
+            Directory ifd = metadata.getIFD();
+
+            assertNull("Unexpected ICC profile for default gray", ifd.getEntryById(TIFF.TAG_ICC_PROFILE));
+        }
+    }
+
     @Test
     public void testWriteParamJPEGQuality() throws IOException {
         ImageWriter writer = createWriter();
@@ -583,7 +605,7 @@ public class TIFFImageWriterTest extends ImageWriterAbstractTest<TIFFImageWriter
         // Read original LZW compressed TIFF
         IIOImage original;
 
-        try (ImageInputStream input = ImageIO.createImageInputStream(getClass().getResource("/tiff/a33.tif"))) {
+        try (ImageInputStream input = ImageIO.createImageInputStream(getClassLoaderResource("/tiff/a33.tif"))) {
             ImageReader reader = ImageIO.getImageReaders(input).next();
             reader.setInput(input);