Re: HTML foreground and background colors being the same... poll time!

[Ken McGlothlen <mcglk@serv.net>]

colin@xemacs.org (Colin Rafferty) writes:

| William M Perry writes:
| 
| > I'd vote for (c), but I have no clue on how to go about finding or writing
| > a good contrast-finding algorithm.  Anyone out there know of one?
| 
| I vote for (c), but I know that finding contrasting colors is hard to
| do.  However, since all you need is a single constrasting color, you
| could choose between black and white.
| 
| ;; Take the "average" level, and go opposite
| 
| (defun infer-contrasting-color (r g b)
|   (if (and (<= r 255)
| 	   (<= g 255)
| 	   (<= b 255))
|       (if (< (+ r g b) 384) "white" "black")   ; (/ (* 256 3) 2) => 384
|     (if (< (+ r g b) 98304) "white" "black"))) ; (/ (* 65536 3) 2) =>  => 382
| 
| ;; Colin

This is actually a slight improvement to the one I was going to suggest; I
guess I've been doing web stuff for so long, I forgot about 16-bit color.  :)

This is perhaps slightly less boring than the complement one, but does produce
readable results in all cases, even the annoyingly borderline ones, and it's
the one I'd support.

Of course, a gnus-select-perfect-colors-based-on-subject-matter function might
be better, but might make the package run a bit slow.  :)