--- /dev/null	2017-05-22 14:23:35.000000000 -0700
+++ new/test/javax/imageio/plugins/png/ImageCompare.java	2017-05-22 14:23:34.000000000 -0700
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2000, 2017, 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.
+ */
+
+import java.awt.image.BufferedImage;
+import java.awt.image.ColorModel;
+import java.awt.image.Raster;
+
+// Utility to compare two BufferedImages for RGB equality
+public class ImageCompare {
+
+    public static void compare(BufferedImage oldimg,
+                               BufferedImage newimg) {
+        int width = oldimg.getWidth();
+        int height = oldimg.getHeight();
+        if (newimg.getWidth() != width || newimg.getHeight() != height) {
+            throw new RuntimeException("Dimensions changed!");
+        }
+
+        Raster oldras = oldimg.getRaster();
+        ColorModel oldcm = oldimg.getColorModel();
+        Raster newras = newimg.getRaster();
+        ColorModel newcm = newimg.getColorModel();
+
+        for (int j = 0; j < height; j++) {
+            for (int i = 0; i < width; i++) {
+                Object oldpixel = oldras.getDataElements(i, j, null);
+                int oldrgb = oldcm.getRGB(oldpixel);
+                int oldalpha = oldcm.getAlpha(oldpixel);
+
+                Object newpixel = newras.getDataElements(i, j, null);
+                int newrgb = newcm.getRGB(newpixel);
+                int newalpha = newcm.getAlpha(newpixel);
+
+                if (newrgb != oldrgb ||
+                    newalpha != oldalpha) {
+                    throw new RuntimeException("Pixels differ at " + i +
+                                               ", " + j);
+                }
+            }
+        }
+    }
+}