bug#41544: 26.3; Possible incorrect results from color-distance

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Mon, 1 Jun 2020 19:24:45 +0200
> Cc: tom@tromey.com, simon@polaris64.net, 41544@debbugs.gnu.org
> 
> > I'm worried because the way our automatic color mapping on
> > color-challenged TTYs works took some time to get right, and it worked
> > well for years.  If we want to risk rocking that particular boat som
> > profoundly, we had better had a very good reason, preferably several
> > good reasons.
> 
> Not quite sure what you are talking about here. You previously asked about 
> the exact value of TTY_SAME_COLOR_THRESHOLD. Were you unsatisfied with my 
> answer, and if so, in what respect?

I'm just looking at the changes.  I see a change in how colors are
converted to RGB triplets.  I see a change in what colors are
considered dark and light, with a new function which decides that that
is being used for frame background mode and in several lisp/term/
files, including 16-color terminals.  I'm asking why do we want to
make all those changes, which modify very basic aspects of our color
support on many terminals.