on 1/14/01 1:46 PM, photoscientia at [EMAIL PROTECTED]
wrote:
> I've measured my monitor as having a 600:1 brightness range, a good paper
> print
> has what? 200:1?
What's that got to do with color gamut?
> A small shift in the green phosphor would eliminate the discrepancy, but the
> comparison between reflective and self-luminous colour spaces is problematic
> in any case.
You can't simply shift the green phosphor if they can't go any farther. It's
not like the movie "Spinal Tap" where you can crank up the amplifier to 11.
Today's displays don't have the gamut to do what we want (produce a pure
cyan on screen).
> The Epson 1270 is reckoned by many people to give one of the best outputs you
> can
> obtain with inks, so I would have thought that matching it's gamut would be a
> good
> test of any RGB space.
Here's the gamut of a 1270 using Photo paper next to sRGB. As I've mentioned
in the past, output devices have gamut's who's shapes are quite different
from RGB Working Spaces as you can see here. As you can see, the cyans and
greens fall far outside sRGB. sRGB is a bit wider in reds. The Epson is
short, as you'd expect in blues.
> IMHO the SWOP colour diagram is a 'cheat'.
> It seems to me as if the publishers of that chart have some vested interest in
> making RGB spaces look bad. Are they half-tone ink manufacturers by any
chance?
The gamut maps are generated from the profiles for both devices. The SWOP
profile was created by Heidelberg from measured data of ink sheets from a
press that confirms to TR001 SWOP spec. I have plenty of profiles I've made
myself from CMYK proofing devices (Matchprint, Iris, Kodak Approval) which
I'd be happy to map. But TR001 is a specific press standard that actually
defines SWOP (anything not conforming to TR001 isn't officially SWOP even
though you or a printer can call it SWOP).
Andrew Rodney
Epson vs. sRGB
