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Re: Frame background mode


From: Luc Teirlinck
Subject: Re: Frame background mode
Date: Tue, 28 Dec 2004 14:42:50 -0600 (CST)

Juri Linkov wrote:

   I suggest to improve the formula used to determine whether the
   background is light or dark.  The new formula uses the optimal
   weighting coefficients for RGB color components to reflect the
   perception of color luminance.

and:

   +               (>= (+ (* (nth 0 bg-color-values) 0.30)
   +                      (* (nth 1 bg-color-values) 0.59)
   +                      (* (nth 2 bg-color-values) 0.11))

Where did you get the .30 .59 .11 from?

The way colors are perceived, including their brightness, depends on
many things.  Your monitor, your eyes, the background colors you are
currently looking at (background color of your screen, color of your
walls), the kind of light that is present other than the light
produced by your computer (daylight, artificial light, the exact
wavelength distribution of that artificial light, no additional
light...), the intensity and angle of that light and so on.

If you have an abnormal color vision, like me (I am a very abnormal
trichromat) you have to customize your monitor.  Customizing every
single color for every single program you are using is hopeless. 

If I use the default settings of my monitor, the most basic color,
white, 255 255 255, looks to me like light green with some shade of
light blue, in other words, a greenish cyan.  It probably looks
perfectly white to most other people.  (Actually, if I allow direct
sunlight to hit my monitor, it turns white, even for me.)  Green, 
0 255 0 looks tremendously brighter than blue, 0 0 255, which in turn
looks tremendously brighter than red, 255 0 0.  I can _see_ red text
on a black background, but not read it.  Same with cyan on white,
which is actually cyan on lighter and greener cyan.  Same with yellow
on white, which is actually light green on a more bluish light green.

So I have to customize my monitor.  The question is: what strategy do
I need to use to customize it?  What I did is I tried to make red,
green and blue equally bright.  Now, under my usual (day)light
conditions, white looks white and I have less trouble with
unreadability due to bad (for me) color combinations.  If I allow
direct sunlight to hit my monitor, then my de-cyanized white turns
bright rose, but I better not allow that to happen anyway.  Ideally, I
would need different customizations of my monitor for day and night
use, but the difference, while noticeable, is not really big enough to
be worth that trouble.

If I understand correctly the old code assumed that red, green and
blue have exactly the same brightness.  For my monitor, eye and usual
conditions, that is actually correct, because I made it correct.
Again, if I understood correctly, your code assumes that green is, to
some specified degree, brighter than red, which is brighter than blue.
Again, where did you get these numbers from?  What brightness relation
do people who construct monitors _try_ to achieve under which
conditions?

I agree with Eli that it is better not to mess with this until after
the release.

Sincerely,

Luc.




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