Compare two images in Java

Question

Compare two images in Java

saadabc (Programmer)

(OP)

22 Jul 06 19:10

Hi,
I'm trying to compare 2 images to see if they are the exact same or not ....

I'm assuming I would have to compare the bytes representation of the 2 images. I cannot find any methods in the Image, BufferedImage etc classes to get the bytes of the image.

Can anyone help?

Thanks-in-advance.

sedj (Programmer) · Answer 1 · 2006-07-23 04:36:26

I think you would do it like this :

CODE

BufferedImage bi ...

Raster r = bi.getData();
DataBuffer db = r.getDataBuffer();
int size = db.getSize();

for (int i = 0; i < size; i++) {
int px = db.getElem(i);
}

The first thing to do would be to check that the size of the data buffer are the same for both images, and then if they are, compare both images in the for loop.

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saadabc (Programmer) · Answer 2 · 2006-07-23 04:59:27

How do I initialize BufferedImage from a pre-existing image saved on the computer hardrive. e.g, C:\test.jpg .

There doesn't seem to be a filename or path parameter in any of the constructors, or other methods.

Thanks.

Waseem

sedj (Programmer) · Answer 3 · 2006-07-23 05:03:47

BufferedImage bi = ImageIO.read(new File("bla.jpg"));

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saadabc (Programmer) · Answer 4 · 2006-07-23 18:47:23

Thanks - this works!!!

One more question. Do you know where in the data buffer for the image is the information for the background color of the image stored.

sedj (Programmer) · Answer 5 · 2006-07-24 02:26:12

I think it is in the ColorModel for the Raster - just read the API documentation for the classes used - you should find your information there.

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Compare two images in Java