Re: I need a comparison/hashing algorithm (not the usual).

Another theoretical approach would be to compress both images into JPEGs and then parse the JPEG file for the 8x8 chunks

Calculate a hash for each of the chunks and then you could compare the list of hashes for each image.

Alternatively you could break each image up into 8x8 chunks and then "naively" quantise them (take it down to 12bit or even 9 bit colour depth).
Then calculate the average and median for each of the quantised chunks and compare the lists of values for each image.

Cheers The Cat

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Re^2: I need a comparison/hashing algorithm (not the usual). by Cap'n Steve (Friar) on Sep 24, 2004 at 18:55 UTC
Wow, there's definitely some good ideas there, thanks guys. This is all theoretical at the moment so I'm just investigating the possibilities, but I'll be sure to read up on some of the suggestions.	[reply]