>>I would suggest that editing the image and saving it (without actually making changes) is actually altering the compression level of the jpg So, in fact, the image has changed.
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>>If it's not actually changing the compression level, then I would guess the jpg header is being modified. Compare the files with a hex editor and then, if that is the case, strip out the header string prior to comparison.
>>
>>In the end, it sounds like you want more of a soundex() for images? Can't help there. Sorry.
>
>Thanks for the feedback. A soundex() for images would be nice!

I suspect Brandon is right, Paint is probably changing the compression level to what it thinks is "correct".

What you might be able to do is determine the compression level before anyone does any editing, then when it's saved again, make sure the same compression level is used. While I can't offer any specifics one place you could start looking is in the GDIPlusX library: http://www.codeplex.com/wikipage?ProjectName=VFPX&title=GDIPlusX . There are some people on this forum knowledgeable with this library who can probably help.