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?

Note: instead of this: `if (i1 == i2){ return true; } else { return false; }` always do this: `return (i1 == i2);`. This won't solve your problem in this case, but it's much cleaner looking. — Cory Kendall, Mar 08 '13 at 23:28
Possible duplicate of [Is there a simple way to compare BufferedImage instances?](http://stackoverflow.com/questions/11006394/is-there-a-simple-way-to-compare-bufferedimage-instances) — N Kumar, Oct 20 '15 at 18:23

score 26 · Accepted Answer · edited Jan 31 '14 at 00:13

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;
}

score 1 · Answer 2 · answered Mar 08 '13 at 23:26

1

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

answered Mar 08 '13 at 23:26

evanmcdonnal

46,131
16
104
115

OP states that he has `BufferedImage`s, he may not have the actual files themselves. – devrobf Mar 08 '13 at 23:32
@jazzbassrob if that's the case the bytes are already in memory so it only makes the comparison easier. – evanmcdonnal Mar 09 '13 at 00:23
@evanmcdonnal for example? They're not even in a file format yet. – Cruncher Dec 10 '15 at 16:57

score -3 · Answer 3 · answered Jan 04 '17 at 15:50

-3

What about hash codes?

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

answered Jan 04 '17 at 15:50

SimmaDahnNah

1

3

It's not save to assume that data is the same if the hashcode is the same. You still have to compare the actual data – doerig Jan 04 '17 at 16:15
Worse yet: Both `BufferedImage` and `BufferedImage.getData()` return different hashes for the same data. They don't implement `hashCode()` – Mark Jeronimus May 19 '22 at 13:01

Java Compare one BufferedImage to Another

3 Answers3

Linked