Re: PNG pictures have gamma correction twice applied

[Richard Stallman]

    When a PNG image is displayed, first all the gamma correction factors
    of the screen and image are taken into account, and the PNG library
    is called with that information.  The resulting color triples are in
    properly gamma-adjusted 24bit color space, ready for putting on the
    screen.

Is the same thing true for other image formats, or only for PNG?

             Then Emacs looks up every pixel in a lookup table, and if it
    does not find it there, it again does gamma correction and other
    stuff.

The fix would seem to be to delete the second gamma correction.  The
two hard questions are (1) where this code is and (2) whether the
change needs to be made for all image formats or just for PNG.

It sounds like you know the answer to (1).  Could you tell us?
Would someone like to investigate the answer to (2)?