I'm currently trying to figure out how JPEG's are made in depth out of interest. I found documents on the different sections (soi, sof, sos, eoi etc) which are pretty straight forward, but not how to get a single pixel out of there.
My first thought was to make a small image, 2x2 for example, but with all the headers and sections it's still to big to isolate the pixel information without knowing the exact location and method to extract it. I'm sure it's compressed, but is their a way to get it out manually? (as RGB?)
Anyone has a clue on how to do this?
Getting the value of a single pixel of a JPEG image requires parsing some (if not most) of those sections anyway.
There's a good step-by-step guide available at https://www.imperialviolet.org/binary/jpeg/ (though the code is in Haskell, so it might be moderately inscrutable to mere mortals) that explains the concepts behind turning a JPEG into a bunch of RGB values.