5:6:5 RGB Considered Harmful

[Jim Gettys]

More than most people will know:

To save money on the backlight, we match the colors of the LED's in the
backlight, but allow much more variation of color than you'd naively
expect.  This lets us use much cheaper LED's (by using most LED's
produced, rather than just those that happen to match a pretty arbitrary
specification, and the eye is very good at compensating for different
colors (so long as they match).

This is why we don't normally notice much difference in white between
white from sunlight, fluorescent lights, or incandescent, which are
actually quite different colors.
                                    - Jim


On Mon, 2007-03-12 at 11:00 -1000, Mitch Bradley wrote:
> 
> Benjamin M. Schwartz wrote:
> > Quoting Albert Cahalan <acahalan at gmail.com>:
> >   
> >> 5:6:5 can't even do grey.
> >>     
> >
> > I can't speak to the other problems with 565, but this one can be partially
> > remedied.  In 565, white is normally (31,63,31).  If we change our display's
> > color balance so white is (31,62,31) then there are 30 available exact shades
> > of gray.
> >
> > We lose essentially no precision, and the format becomes a strict superset of
> > 555.
> > Of course, (31,63,31) would be clipped to white.
> >   
> I expect that the unit-to-unit variance in the color temperature of the 
> backlight LEDs exceeds 1 LSB  of green in 565.
> 
> > Just a thought.
> >
> > --Ben
> >
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-- 
Jim Gettys
One Laptop Per Child