public static Bitmap convertGreyImg(Bitmap img) { int width = img.getWidth(); //获取位图的宽 int height = img.getHeight(); //获取位图的高 int[] pixels = new int[width * height]; //通过位图的大小创建像素点数组 img.getPixels(pixels, 0, width, 0, 0, width, height); int alpha = 0xFF << 24; for (int i = 0; i < height; i++) { for (int j = 0; j < width; j++) { int original = pixels[width * i + j]; int red = ((original & 0x00FF0000) >> 16); int green = ((original & 0x0000FF00) >> 8); int blue = (original & 0x000000FF); int grey = (int) ((float) red * 0.3 + (float) green * 0.59 + (float) blue * 0.11); grey = alpha | (grey << 16) | (grey << 8) | grey; pixels[width * i + j] = grey; } } Bitmap result = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565); result.setPixels(pixels, 0, width, 0, 0, width, height); return result; }

参考资料:Android实现图片相似度

去看下Android的这个类ColorMatrix
Android的矩阵(一)：ColorMatrix