--- a/jdk/src/java.desktop/share/classes/com/sun/imageio/plugins/gif/GIFImageWriter.java	Wed Oct 12 23:04:39 2016 +0530
+++ b/jdk/src/java.desktop/share/classes/com/sun/imageio/plugins/gif/GIFImageWriter.java	Thu Oct 13 11:37:32 2016 +0530
@@ -1314,7 +1314,7 @@
         super(locale);
         this.canWriteCompressed = true;
         this.canWriteProgressive = true;
-        this.compressionTypes = new String[] {"LZW", "lzw"};
+        this.compressionTypes = new String[] {"LZW"};
         this.compressionType = compressionTypes[0];
     }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/javax/imageio/ImageCompressionTypesTest.java	Thu Oct 13 11:37:32 2016 +0530
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+ /*
+  * @test
+  * @bug     6294607
+  * @summary Test verifies whether ImageWriteParam.getCompressionTypes()
+  *          returns any duplicate compression type for ImageIO plugins.
+  * @run     main ImageCompressionTypesTest
+  */
+
+import java.util.Iterator;
+import javax.imageio.ImageIO;
+import javax.imageio.ImageWriteParam;
+import javax.imageio.ImageWriter;
+
+public class ImageCompressionTypesTest {
+
+    static ImageWriter writer = null;
+
+    public ImageCompressionTypesTest(String format) {
+        Iterator it = ImageIO.getImageWritersByFormatName(format);
+        while (it.hasNext()) {
+            writer = (ImageWriter) it.next();
+            break;
+        }
+        ImageWriteParam param = writer.getDefaultWriteParam();
+
+        param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
+        System.out.println("Checking compression types for : " + format);
+        String compTypes[] = param.getCompressionTypes();
+        if (compTypes.length > 1) {
+            for (int i = 0; i < compTypes.length; i++) {
+                for (int j = i + 1; j < compTypes.length; j++) {
+                    if (compTypes[i].equalsIgnoreCase(compTypes[j])) {
+                        throw new RuntimeException("Duplicate compression"
+                                + " type exists for image format " + format);
+                    }
+                }
+            }
+        }
+    }
+
+    public static void main(String args[]) {
+        final String[] formats = {"bmp", "png", "gif", "jpg", "tiff"};
+        for (String format : formats) {
+            new ImageCompressionTypesTest(format);
+        }
+    }
+}
+