On 21 March 2018 at 07:38, Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Richard Copley <rcopley@gmail.com>
> > Date: Tue, 20 Mar 2018 19:56:12 +0000
> > Cc: John Wiegley <johnw@gnu.org>, Tom Tromey <tom@tromey.com>,
> >       Emacs Development <emacs-devel@gnu.org>
> >
> > Patch 1 is a small fix for the current formula using color-distance.
> > Patch 2 uses luminance as in Tom's original patch.
> > I think patch 2 gives better contrast.
>
> Thanks, but I think this is a step backward, as it more or less goes
> back to the code before the discussion of bug#25525.
>

Patch 2 does, yes. It's good to step backwards, because (the effect of) the
original code was OK, whereas the current code leads to unreadable text.

How about making the threshold a customizable value instead, with the
> current hard-coded value the default?  That'd be compatible, and
> should allow you to get the contrast of your liking.
>

It sounds like you want to insist that white-on-pale-green is somehow
better than black-on-pale-green, or that there's some other consideration
that's more important.
I don't understand.