[argyllcms] Re: Custom Illuminant

  • From: Roger Breton <graxx@xxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 08 Jul 2014 14:33:56 -0400

If memory serves, BetaRGB was created by Bruce Lindbloom a long time ago to
fully encompass one the going CMYK color gamut, was it SWOP? Its algorithms
were tuned to search the RGB primaries that would result in no clipping for
this "reference" CMYK gamut, if I recall. Ever heard of ColorSynergy from
PictoColor? Brings back lots of fond memories.

/ Roger

-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Ben Goren
Sent: 8 juillet 2014 13:58
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Custom Illuminant

On Jul 8, 2014, at 10:01 AM, Roger Breton <graxx@xxxxxxxxxxxx> wrote:

> My very humble experience is leading me to believe that there are very 
> few instances of saturated colors in photographs or every day pictorials?

Saturated colors are very uncommon. Most colorants have spectral profiles
similar to those of the paints artists and home painters use. Yellows,
oranges, and reds all reflect nothing shorter than a certain wavelength and
have a steep transition to being highly reflective (and basically flat) at
some point; where that point is is what determines their color, and how
sharp the transition is determines their saturation. Greens and blues and
violets have a single spectral peak that doesn't tend to be all that bright.
The wavelength of the peak determines hue again, and the slope of the peak
determines saturation. Then, of course, there're all the mixtures, including
many metameric matches with much more complex spectra.

To get truly saturated colors you generally need quantum mechanics:
diffraction gratings and variations on that theme (including butterfly
wings), or lasers. (There are other sources, but none common).

But, even if you're photographing something iridescent or a laser light show
or the like...how are you going to output those saturated colors?

Your monitor isn't going to come close. Your printer doesn't stand a chance.

Unless you're doing some sort of empirical analysis, the fact that you've
got a digital file with numbers representing those colors really doesn't do
you much good.

There might be some large gamut monitors or printers that are finally
pushing the boundaries of BetaRGB. It's probably a good time to start
thinking about an update (GammaRGB?) with a gamut expanded enough to
accommodate the next couple generations of devices. But, unless you're
already outputting to something with a gamut larger than BetaRGB, you're
basically not going to find a better compromise than what BetaRGB already
represents.

b&


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