CODEWITHSUNDEEP
javaandroidchecksumduplicates
Karthik Balakrishnan
Karthik Balakrishnan

Reputation: 4393

Duplicate has different MD5 checksum

WhatsApp creates duplicate copies of images upon sharing. Although the resolution of the images are same, the MD5 checksum of the original image and it's copy are different. Why is this? How do I get my app to realize that this is a duplicate image.

I've tried MD5 and Sha-1, both of the algorithms generated different checksums for the two images.

Upvotes: 0

Views: 1325

Answers (1)

vaughandroid
vaughandroid

Reputation: 4374

Sounds like there's probably a difference in the metadata - e.g. the timestamp might have been changed by the WhatsApp servers when the copy was made.

I suggest you retrieve the pixel data for the images and run your checksums on that. You can use the Bitmap.getPixels() method. e.g.: myBitmap.getPixels(pixels, 0, myBitmap.getWidth(), 0, 0, myBitmap.getWidth(), myBitmap.getHeight());

Remember, just because the checksum is the same that doesn't necessarily mean the images are! If your checksums match, you'll have to do an element-by-element comparison of the data to be 100% sure that the images are identical.

Edit: There's a good example of how to do a pixel-by-pixel test for equality here. Note you can use the Bitmap.sameAs() method if you're using API 12+!

Upvotes: 1

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