Re: RGB Color Space Info Request
Re: RGB Color Space Info Request
- Subject: Re: RGB Color Space Info Request
- From: Don Hutcheson <email@hidden>
- Date: Fri, 22 Nov 2002 22:43:02 -0500
All my clients use either DonRGB or BestRGB because the default RGB spaces
provided with Photoshop (Adobe98, ColorMatch RGB, Apple RGB, sRGB, etc)
actually 'clip' or 'plug' detail in highly-saturated transparencies or
digital files. This is because simplified RGB profiles do not contain a
gamut compression tag, so out-of-space colors are simply truncated with no
attempt at hue or lightness preservation.
For example, when you convert from a scanner profile (which should reproduce
even the most saturated original essentially perfectly) to a 'clipping' RGB
space, the difference between two very saturated reds, one cold and one
warm, can be irretrievably lost, even before you start editing the image.
The reason nobody seems to notice this is that the average monitor won't
show these colors either. In fact most of the common RGB spaces derive from
video display roots.
But the gamut of a good SWOP or commercial press often exceeds that of even
the best commercially-affordable CRT or LCD display, and the terrible fact
is that converting into one of the common RGB spaces actually reduces the
effective gamut of the final printed piece! The range of offset lithography
is limited enough already. The last thing you want to do is restrict it even
further due to monitor limitations.
To solve this problem, both DonRGB and BestRGB encompass the full gamut of
virtually any transparency film and enclose the full gamut of even the best
commercial press. So when you convert into either of these spaces, all
colors in the original are maintained, even if you can't see them on your
monitor. When you convert from DonRGB or BestRGB to your CMYK space, instead
of clipping the out-of-gamut colors, the gamut compression built into all
good CMYK profiles carefully re-maps extremely saturated colors to maintain
at least a hint of their original hue and shape.
You can see the gamut differences between different RGB spaces in my free
Microsoft Excel spreadsheet "RGB_coords" at www.hutchcolor.com. But a much
better way to visualize the difference between RGB spaces and press gamuts
is to buy Steve Upton's incredibly cool and useful "ColorThink" from
www.chromix.com. As already mentioned by numerous other posts, it's far and
away the best tool available today for understanding color spaces and ICC
profiles. In fact I insist that all my clients get a copy.
Don
*************************************
Don Hutcheson
Hutcheson Consulting
(Color Management Solutions)
Phone: (908) 689 7403
Mobile: (908) 500 0341
email@hidden
*************************************
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