Even removing the metadata, a hash comparison is unlikely to be useful. Only one bit of data has to be different for the hash comparison to fail. Let’s do a quick experiment.
A 640x480 image has 307,200 pixels. If one pixel is different, we can say that the image is 99.9997% similar. So, using the number 1 to represent a pixel, I pasted 307,200 1 characters into an SHA-256 hash generator. The generated hash was:
Changing the last 1 to a 0 resulted in the following hash:
Using the following string similarity tester, this shows that the two hashes are 38.28% similar:
So, even if you remove the metadata, unless each pixel in the image is 100% identical, you will not have an identical hash, or even one that is comparable.
Edit: Looks like you typed a reply while I was doing this. This reply is meant to be in response to this post: http://support.plugable.com/plugable/…