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.