Re: RGB Color Space Info Request
Re: RGB Color Space Info Request
- Subject: Re: RGB Color Space Info Request
- From: bruce fraser <email@hidden>
- Date: Mon, 25 Nov 2002 17:34:48 -0800
At 12:14 PM +1100 11/26/02, Graeme Gill wrote:
"Bruce J. Lindbloom" wrote:
So it got me thinking. Is the choice of working space important? How do you
choose the best working space? (I suppose you could just pick "BestRGB"
since they wouldn't have let Don Hutcheson name it that if it wasn't really
the best, right? Just teasing you, Don.) How do you compare the relative
merits of two working spaces? What are the desirable properties of a working
space? How would you go about designing one that meets certain criteria
(aside from using trial and error)? These are tough questions, and the more
I think about them, the more I realize how little I understand about this.
Maybe this is a dumb suggestion (I'm not that familiar with Photoshop,
and I haven't played with the latest and greatest), but surely
the right answer is not to use any device dependent space as
a "working space". Use a device independent space that doesn't
have any gamut restrictions. 8 bit Lab might be a first cut
approximation (although perhaps overly quantized for many peoples
taste). Perhaps there is room for someone to standardize an
11 bit Lab interchange/working space ? (ie. use 32 bits per Lab pixel).
In what sense would you consider spaces like Adobe RGB, Best RGB or
Ektaspace device-dependent?
The problem with zero gamut restrictions is that, if you're limited
to three primaries, any space that covers the entire range of human
color vision necessarily encompasses not just all the colors we can
see, but a whole bunch of primary values that don't correspond to
anything we can see, let alone capture or reproduce. So you're
wasting an awful lot of bits.
Photoshop 7 actually supports 48-bit Lab. It's a nice space for
archiving raw captures from high-bit devices, but it's not a great
deal of fun for editing, particularly editing wide-gamut material
where the hue errors inherent in Lab become painfully obvious.
Device-independent RGB spaces offer a fairly elegant solution -- the
main problem is that there are too damn many of them (and to the
small extent to which I've contributed to that, I apologize...)
--
email@hidden
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