Tony writes ...
> On Wed, 17 Jan 2001 10:02:16 -0800 shAf
> ([EMAIL PROTECTED]) wrote:
>
> > ...
> > without regard to monitor gamut, 0-0-255 falls outside
> > the L*a*b gamut... which is the only color
> > definition defined to come even close to
> > physical reality.
>
> I think you are only illustrating that 16.4m colours far
> exceeds the discrimination of human vision, and that
> 8 bits should be enough for anything we intend looking at.
Altho I agree 8bits is enough (barely) to provide human
discrimination, I don't agree with any of the 16M colors being beyond
human discrimination. Perhaps you can point to an example(?) I'm
actually saying all of the 16M colors do not exist, in human
perception or physical reality.
> You can, though, often see differences of ~3-5L
> if there is a suitable reference, though
> it depends on the colour and luminance.
My "perfect" camera/film/scanner" analogy stated the point I wanted
to make regarding RGB=0-0-255. Another would be a L*a*b conversion.
That is, if you create an image of false colors ... 360 degree hue
left-to-right and brightness vertically ... you'll have a
representation of ALL (almost) RGB values. If you accept that Lab is
the best model we have for human perception and the colors available
in nature, then if you convert from RGB=>Lab and then convert back
(highbits please), you'll end up with an image which looks a lot like
the original, but if you diff the original with the converted, you'll
realize the number of pixels which fell outside Lab space. It is damn
near half of the image!
Of course anyone can point to some problems associated with my
experiment ... conversion artifacts, the CM engine and its rendering
intent ... but I've played with combinations, and all imply a similar
number of RGB values which are outside Lab.
Real colors are comprised of a volume inside the RGB "cube" ...
RGB=0-0-255, and a number of other RGB values, are not inside the
"real colors" volume". An interesting debate would be the acceptance
of Lab color space as a representation of "real" colors. Why or why
not is beyond my knowledge, but I've read a number of implications
which would claim so.
shAf :o)
