Java Compare one BufferedImage to Another

Question

I need to compare two buffered images to see if they are the exact same. Simply saying if that equals that doesn't work. My current method is

                 { 
                 Raster var1 = Img1.getData();    
                 Raster var2 = Img2.getData();

                 int Data1 = (var1.getDataBuffer()).getSize();
                 int Data2 = (var2.getDataBuffer()).getSize();

                 if (Data1 == Data2)
                         {
                         return true;
                         }
                 else 
                           {
                           return false;
                           }
                 }

But that doesn't really work. What other more reliable way is there?

Answer 1

The obvious solution would be to compare, pixel by pixel, that they are the same.

boolean bufferedImagesEqual(BufferedImage img1, BufferedImage img2) {
    if (img1.getWidth() == img2.getWidth() && img1.getHeight() == img2.getHeight()) {
        for (int x = 0; x < img1.getWidth(); x++) {
            for (int y = 0; y < img1.getHeight(); y++) {
                if (img1.getRGB(x, y) != img2.getRGB(x, y))
                    return false;
            }
        }
    } else {
        return false;
    }
    return true;
}

Answer 2

Yeah, assuming they are both in the same format read them as byte strings and compare the bit strings. If one is a jpg and the other a png this won't work. But I'm assuming equality implies they are the same.

here's an example on how to do the file reading;

http://www.java-examples.com/read-file-byte-array-using-fileinputstream

Answer 3

What about hash codes?

img1.getData().hashCode().equals(img2.getData().hashCode())