// 全流程

 public static void main(String[] args) throws IOException {

     // 获取图像

     File imageFile = new File("c:/1.jpg");

     Image image = ImageIO.read(imageFile);

     // 转换至灰度

     image = toGrayscale(image);

     // 缩小成32x32的缩略图

     image = scale(image);

     // 获取灰度像素数组

     int[] pixels = getPixels(image);

     // 获取平均灰度颜色

     int averageColor = getAverageOfPixelArray(pixels);

     // 获取灰度像素的比较数组（即图像指纹序列）

     pixels = getPixelDeviateWeightsArray(pixels, averageColor);

     // 获取两个图的汉明距离（假设另一个图也已经按上面步骤得到灰度比较数组）

     int hammingDistance = getHammingDistance(pixels, pixels);

     // 通过汉明距离计算相似度，取值范围 [0.0, 1.0]

     double similarity = calSimilarity(hammingDistance);

 }

 // 将任意Image类型图像转换为BufferedImage类型，方便后续操作

 public static BufferedImage convertToBufferedFrom(Image srcImage) {

     BufferedImage bufferedImage = new BufferedImage(srcImage.getWidth(null),

             srcImage.getHeight(null), BufferedImage.TYPE_INT_ARGB);

     Graphics2D g = bufferedImage.createGraphics();

     g.drawImage(srcImage, null, null);

     g.dispose();

     return bufferedImage;

 }

 // 转换至灰度图

 public static BufferedImage toGrayscale(Image image) {

     BufferedImage sourceBuffered = convertToBufferedFrom(image);

     ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);

     ColorConvertOp op = new ColorConvertOp(cs, null);

     BufferedImage grayBuffered = op.filter(sourceBuffered, null);

     return grayBuffered;

 }

 // 缩放至32x32像素缩略图

 public static Image scale(Image image) {

     image = image.getScaledInstance(32, 32, Image.SCALE_SMOOTH);

     return image;

 }

 // 获取像素数组

 public static int[] getPixels(Image image) {

     int width = image.getWidth(null);

     int height = image.getHeight(null);

     int[] pixels = convertToBufferedFrom(image).getRGB(0, 0, width, height,

             null, 0, width);

     return pixels;

 }

 // 获取灰度图的平均像素颜色值

 public static int getAverageOfPixelArray(int[] pixels) {

     Color color;

     long sumRed = 0;

     for (int i = 0; i < pixels.length; i++) {

         color = new Color(pixels[i], true);

         sumRed += color.getRed();

     }

     int averageRed = (int) (sumRed / pixels.length);

     return averageRed;

 }

 // 获取灰度图的像素比较数组（平均值的离差）

 public static int[] getPixelDeviateWeightsArray(int[] pixels,final int averageColor) {

     Color color;

     int[] dest = new int[pixels.length];

     for (int i = 0; i < pixels.length; i++) {

         color = new Color(pixels[i], true);

         dest[i] = color.getRed() - averageColor > 0 ? 1 : 0;

     }

     return dest;

 }

 // 获取两个缩略图的平均像素比较数组的汉明距离（距离越大差异越大）

 public static int getHammingDistance(int[] a, int[] b) {

     int sum = 0;

     for (int i = 0; i < a.length; i++) {

         sum += a[i] == b[i] ? 0 : 1;

     }

     return sum;

 }

 // 通过汉明距离计算相似度

 public static double calSimilarity(int hammingDistance){

     int length = 32*32;

     double similarity = (length - hammingDistance) / (double) length;

     // 使用指数曲线调整相似度结果

     similarity = java.lang.Math.pow(similarity, 2);

     return similarity;

 }