Percentage difference between images: Difference between revisions

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@@ Line 735: / Line 735: @@
 <lang java>import java.awt.image.BufferedImage;
-import javax.imageio.ImageIO;
+import java.io.File;
 import java.io.IOException;
-import java.net.URL;
+import javax.imageio.ImageIO;
-public class ImgDiffPercent
+public enum ImgDiffPercent {
+    ;
-{
-  public static void main(String args[])
+    public static void main(String[] args) throws IOException {
-  {
+        // https://rosettacode.org/mw/images/3/3c/Lenna50.jpg
-    BufferedImage img1 = null;
+        // https://rosettacode.org/mw/images/b/b6/Lenna100.jpg
-    BufferedImage img2 = null;
+        BufferedImage img1 = ImageIO.read(new File("Lenna50.jpg"));
-    try {
-      URL url1 = new URL("http://rosettacode.org/mw/images/3/3c/Lenna50.jpg");
+        BufferedImage img2 = ImageIO.read(new File("Lenna100.jpg"));
-      URL url2 = new URL("http://rosettacode.org/mw/images/b/b6/Lenna100.jpg");
-      img1 = ImageIO.read(url1);
+        double p = getDifferencePercent(img1, img2);
-      img2 = ImageIO.read(url2);
+        System.out.println("diff percent: " + p);
-    } catch (IOException e) {
-      e.printStackTrace();
     }
-    int width1 = img1.getWidth(null);
+    private static double getDifferencePercent(BufferedImage img1, BufferedImage img2) {
-    int width2 = img2.getWidth(null);
-    int height1 = img1.getHeight(null);
+        int width = img1.getWidth();
-    int height2 = img2.getHeight(null);
+        int height = img1.getHeight();
-    if ((width1 != width2) || (height1 != height2)) {
+        int width2 = img2.getWidth();
+        int height2 = img2.getHeight();
-      System.err.println("Error: Images dimensions mismatch");
+        if (width != width2 || height != height2) {
-      System.exit(1);
+            throw new IllegalArgumentException(String.format("Images must have the same dimensions: (%d,%d) vs. (%d,%d)", width, height, width2, height2));
+        }
+        long diff = 0;
+        for (int y = 0; y < height; y++) {
+            for (int x = 0; x < width; x++) {
+                diff += pixelDiff(img1.getRGB(x, y), img2.getRGB(x, y));
+            }
+        }
+        long maxDiff = 3L * 255 * width * height;
+        return 100.0 * diff / maxDiff;
     }
-    long diff = 0;
-    for (int y = 0; y < height1; y++) {
+    private static int pixelDiff(int rgb1, int rgb2) {
-      for (int x = 0; x < width1; x++) {
-        int rgb1 = img1.getRGB(x, y);
-        int rgb2 = img2.getRGB(x, y);
         int r1 = (rgb1 >> 16) & 0xff;
         int g1 = (rgb1 >>  8) & 0xff;
-        int b1 = (rgb1      ) & 0xff;
+        int b1 =  rgb1        & 0xff;
         int r2 = (rgb2 >> 16) & 0xff;
         int g2 = (rgb2 >>  8) & 0xff;
-        int b2 = (rgb2      ) & 0xff;
+        int b2 =  rgb2        & 0xff;
-        diff += Math.abs(r1 - r2);
+        return Math.abs(r1 - r2) + Math.abs(g1 - g2) + Math.abs(b1 - b2);
-        diff += Math.abs(g1 - g2);
-        diff += Math.abs(b1 - b2);
-      }
     }
-    double n = width1 * height1 * 3;
-    double p = diff / n / 255.0;
-    System.out.println("diff percent: " + (p * 100.0));
-  }
 }</lang>