TMI-73: Now handles TIFF files using only the lower 8 bits of each 16 bit entry in the ColorMap.

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

@@ -340,17 +340,7 @@ public class TIFFImageReader extends ImageReaderBase {
                     throw new IIOException("Missing ColorMap for Palette TIFF");
                 }
 
-                int[] cmapShort = (int[]) colorMap.getValue();
+                IndexColorModel icm = createIndexColorModel(bitsPerSample, dataType, (int[]) colorMap.getValue());
-                int[] cmap = new int[colorMap.valueCount() / 3];
-
-                // All reds, then greens, and finally blues
-                for (int i = 0; i < cmap.length; i++) {
-                    cmap[i] = (cmapShort[i                  ] / 256) << 16
-                            | (cmapShort[i +     cmap.length] / 256) << 8
-                            | (cmapShort[i + 2 * cmap.length] / 256);
-                }
-
-                IndexColorModel icm = new IndexColorModel(bitsPerSample, cmap.length, cmap, 0, false, -1, dataType);
 
                 return IndexedImageTypeSpecifier.createFromIndexColorModel(icm);
 
@@ -413,6 +403,43 @@ public class TIFFImageReader extends ImageReaderBase {
         }
     }
 
+    private IndexColorModel createIndexColorModel(final int bitsPerSample, final int dataType, final int[] cmapShort) {
+        // According to the spec, there should be exactly 3 * bitsPerSample^2 entries in the color map for TIFF.
+        // Should we enforce this?
+
+        int[] cmap = new int[cmapShort.length / 3];
+
+        // We'll detect whether the color map data is 8 bit, rather than 16 bit while converting
+        boolean cmapIs8Bit = true;
+
+        // All reds, then greens, and finally blues
+        for (int i = 0; i < cmap.length; i++) {
+            cmap[i] = (cmapShort[i                  ] / 256) << 16
+                    | (cmapShort[i +     cmap.length] / 256) << 8
+                    | (cmapShort[i + 2 * cmap.length] / 256);
+
+            if (cmapIs8Bit && cmap[i] != 0) {
+                cmapIs8Bit = false;
+            }
+        }
+
+        if (cmapIs8Bit) {
+            // This color map is using only the lower 8 bits, making the image all black.
+            // We'll create a new color map, based on the non-scaled 8 bit values.
+
+            processWarningOccurred("8 bit ColorMap detected.");
+
+            // All reds, then greens, and finally blues
+            for (int i = 0; i < cmap.length; i++) {
+                cmap[i] = (cmapShort[i                  ]) << 16
+                        | (cmapShort[i +     cmap.length]) << 8
+                        | (cmapShort[i + 2 * cmap.length]);
+            }
+        }
+
+        return new IndexColorModel(bitsPerSample, cmap.length, cmap, 0, false, -1, dataType);
+    }
+
     private int getSampleFormat() throws IIOException {
         long[] value = getValueAsLongArray(TIFF.TAG_SAMPLE_FORMAT, "SampleFormat", false);
 

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

@@ -29,6 +29,7 @@ package com.twelvemonkeys.imageio.plugins.tiff;/*
 import com.twelvemonkeys.imageio.util.ImageReaderAbstractTestCase;
 import org.junit.Test;
 
+import javax.imageio.ImageReadParam;
 import javax.imageio.ImageReader;
 import javax.imageio.event.IIOReadWarningListener;
 import javax.imageio.spi.ImageReaderSpi;
@@ -176,4 +177,31 @@ public class TIFFImageReaderTest extends ImageReaderAbstractTestCase<TIFFImageRe
             stream.close();
         }
     }
+
+    @Test
+    public void testColorMap8Bit() throws IOException {
+        TestData testData = new TestData(getClassLoaderResource("/tiff/scan-lzw-8bit-colormap.tiff"), new Dimension(2550, 3300));
+
+        ImageInputStream stream = testData.getInputStream();
+
+        try {
+            TIFFImageReader reader = createReader();
+            reader.setInput(stream);
+
+            IIOReadWarningListener warningListener = mock(IIOReadWarningListener.class);
+            reader.addIIOReadWarningListener(warningListener);
+
+            ImageReadParam param = reader.getDefaultReadParam();
+            param.setSourceRegion(new Rectangle(8, 8));
+            BufferedImage image = reader.read(0, param);
+
+            assertNotNull(image);
+            assertEquals(new Dimension(8, 8), new Dimension(image.getWidth(), image.getHeight()));
+            assertEquals(0xffffffff, image.getRGB(0, 0)); // The pixel at 0, 0 should be white, not black
+            verify(warningListener, atLeastOnce()).warningOccurred(eq(reader), contains("ColorMap"));
+        }
+        finally {
+            stream.close();
+        }
+    }
 }