Jon, that image (*) isn't exactly raw. It has undergone some processing. It's been cropped, of course, and also its brightness values have been changed destructively. The pixels in raw.gif have only 41 different brightness values, while the corresponding pixels (the 4,513th through 5,632nd rows) in cydonia1.tif have 53 different brightness values. Twelve values have been removed. I'm attaching for you a graph of the algorithm (a non-invertible integer function) that someone used to create raw.gif.

I'm posting this followup, not because I believe that the slight alteration that was done to raw.gif has any practical importance, but instead because I think that we should try to be extremely clear about which images are raw, and which images have been processed.

(*) sha1sum ("raw.gif") == "6cc5bb505aae76422b9040ab4ddc226264aff32d"

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