Re: Which one has the right color, Emacs or GIMP?

[Stephen J. Turnbull]

Miles Bader writes:

 > Huh?  RGBA is just a notation for a storage format, it says nothing
 > about how the components should or should-not-be interpreted.

Of course it says something.  It says that the various components red,
green, and blue shall be used in strengths given as a fraction of
their maximum, as modified by the alpha if the display is capable.

It's possible to quibble about whether that "strength" must be linear
or merely increasing (the latter interpretation admits gamma
adjustment among others).  But to say "it says nothing" is too much of
a stretch.

I admit I've never read the X Window System Color Management System
documents closely, but I suspect there's a specification there for RGB.

I can say that one of the rationales for RGB.txt was so that color
names could be device-independent, while their RGB values might vary.
But of course that didn't work so well because RGB.txt lives where
libX11 does, not on the server, and nowadays RGB.txt may not be
consulted at all.

 > The gimp, however (and emacs) needs to worry about such things
 > regardless, since in the end it's in charge of what the user sees;
 > hopefully there's helpful meta-data which says what to do...

IMHO, Emacs should delegate this to either the display hardware and
drivers (which should provide a satsifactory default gamma
adjustment), or to another application such as the GIMP.