Re: Fast way to compare two picture-files

looking for the fastest way to compare two picture-Files

Not sure if you are trying to do a "this picture file is a duplicate file of this picture file" or if you're tyring to do some sort of image recognition so I don't know if this is what you are asking for.

If you are just looking at two files to see if they are duplicates one thought I have is to do an MD5 sum on the two files and see if the hash matches. If they match chances are they are the same image. If not they are definitely not hte same image.

Peter L. Berghold -- Unix Professional
Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

Comment on Re: Fast way to compare two picture-files

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Re^2: Fast way to compare two picture-files by ikegami (Patriarch) on Dec 29, 2008 at 02:06 UTC
Why do people always suggest finding the digest to compare two files? Graciously assuming calculating the digest is instantaneous, using the digest method requires reading the entire file whereas one can usually exit after one pair of reads using a byte for byte comparison. Using the digest method is great when comparing a file against multiple others over a long time period. It's a poor method when comparing two files. If they match chances are they are the same image. If you're going to follow up by checking the files byte for byte, it might make more sense to find the digest of the first X bytes of the file instead of the digest of the entire file.	[reply]
Re^3: Fast way to compare two picture-files by abell (Chaplain) on Dec 29, 2008 at 10:17 UTC
It's out of similar considerations that some time ago I wrote dupseek. Even for multiple files, just using parts of file contents instead of digests works quite well (and rules out even the very small risk of collisions). The stupider the astronaut, the easier it is to win the trip to Vega - A. Tucket	[reply]