Tiff file lzw compression bit size needs to be capped at 12

src/main/java/mil/nga/tiff/compression/LZWCompression.java

@@ -38,6 +38,11 @@ public class LZWCompression implements CompressionDecoder, CompressionEncoder {
 	 */
 	private static final int MIN_BITS = 9;
 
+	/**
+	 * Max bits
+	 */
+	private static final int MAX_BITS = 12;
+
 	/**
 	 * Table entries
 	 */
@@ -154,7 +159,7 @@ private void initializeTable() {
 	 * Check the byte length and increase if needed
 	 */
 	private void checkByteLength() {
-		if (maxCode >= Math.pow(2, byteLength) - 2) {
+		if (byteLength < MAX_BITS && maxCode >= Math.pow(2, byteLength) - 2) {
 			byteLength++;
 		}
 	}

src/test/java/mil/nga/tiff/TiffReadTest.java

@@ -1,5 +1,6 @@
 package mil.nga.tiff;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 import java.io.File;
@@ -8,6 +9,7 @@
 import org.junit.Test;
 
 import junit.framework.TestCase;
+import mil.nga.tiff.util.TiffConstants;
 import mil.nga.tiff.util.TiffException;
 
 /**
@@ -373,4 +375,25 @@ public void testFloat32VsLZWPredictorFloatingPoint() throws IOException {
 
 	}
 
+    /**
+     * Test the TIFF file where the LZW bit size requires the cap of 12.
+     *
+     * @throws IOException
+     *             upon error
+     */
+    @Test
+    public void testLzw12BitMax() throws IOException {
+
+        File lzw12BitMaxFile = TiffTestUtils
+                .getTestFile(TiffTestConstants.FILE_LZW_12_BIT_MAX);
+        TIFFImage image = TiffReader.readTiff(lzw12BitMaxFile);
+        assertEquals( 1, image.getFileDirectories().size() );
+        FileDirectory dir = image.getFileDirectory();
+        assertEquals( TiffConstants.COMPRESSION_LZW, dir.getCompression().intValue() );
+        assertEquals( 555, dir.getImageWidth().intValue() );
+        assertEquals( 555, dir.getImageHeight().intValue() );
+
+        dir.readRasters();//this will throw a parsing exception if invalid
+    }
+
 }

src/test/java/mil/nga/tiff/TiffTestConstants.java

@@ -92,4 +92,9 @@ public class TiffTestConstants {
 	 */
 	public static final String FILE_LZW_PREDICTOR_FLOATING = "lzw_predictor_floating.tiff";
 
+    /**
+     * LZW 12 bit max TIFF test file
+     */
+    public static final String FILE_LZW_12_BIT_MAX = "lzw12bitmax.tiff";
+
 }