finding original image on computer by image comparison and not its name

Hello.

I have a peculiar question:

Somewhere on my MAC i have an image that I really need to find.

Not an easy task to look though thousands of files

I do not have the image file name, but have a 72dpi copy of the image which has been renamed and posted on the web.

Can I find the original image on my computer by comparing all images stored on my drive to the smaller 72dpi edition?

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Andrzej
http://lowflyingbananas.zenfolio.com/