Re: RGB Color Space Info Request
Re: RGB Color Space Info Request
- Subject: Re: RGB Color Space Info Request
- From: Jon Meyer <email@hidden>
- Date: Mon, 25 Nov 2002 09:23:14 -0500
Neil has identified the position I firmly agree with.
When I ran a Crosfield to Mac link 12 years ago, the scan was created
for the specific output requirement. It seems most ICC consultants
are still taking that approach.
If on the other hand, information from the chrome can be maintained
for the year 2025 ultra-wide gamut output device, then we should err
on the photographer's behalf.
This led to the development of a family of working spaces. All have
the same primaries, to just cover Ektachrome and Fujichrome. The
contrast at 2.46 is a good chrome saturation match.
Following conversion from input profile to
DA_FilmContrast_Workspace.icc, the resultant file nearly matches the
raw in all ways except the artifacts. Local contrast, separation and
absence of orange/red saturated issues are addressed.
The cool thing is that if a photographer captures an 18% gray card,
it becomes 128s in the RGB file. With proper handling by the output
file, it becomes 18% gray in the final print.
In order to handle the specific needs of the photographer, three
"contrast mask" working spaces finesse the output to create the look
of Portra, Supra and Ultra papers.
By assigning one of these three spaces to the archive quality
FilmContrast file, the contrast of the output is delicately handled.
Let me explain.
Portraits have traditionally liked ColorMatch because of its 1.8
gamma. Assigning DA_PortraContrast_Workspace achieves the same subtle
transitions in skin tone highlight to shadow reproduction, while
maintaining Dmin, midtones and Dmax.
Assigning DA_SupraContrast_Workspace ideally manages output for
fashion and similar work.
Assigning DA_UltraContrast_Workspace is a fantastic way of shaping
the contrast for saturated commercial work. Sky blue, Red Stop Signs,
Big Greens. . . all while maintaining that important midtone
reproduction.
------
While this workflow is a bit more involved than other approaches, it
proves to me significantly more accurate (without editing output
profiles for contrast issues).
Real world tests have been done on output. Remember, viewing
differences on screen is limited to the range of reproduction allowed
by the monitor (where sRGB and Adobe RGB emulate the monitor gamut).
These spaces deal with the range of color and detail which falls
outside of the monitor gamut and reproduction.
------
The Museum of Modern Art in NY as well as the Art Institute in
Chicago and others in all areas of photography and graphics are using
the family of spaces, because of their accuracy.
------
Please contact me offline to obtain the spaces. Online questions will
be addressed through the list.
- Jon
*******************************************************
Jon Meyer
GrafixGear
email@hidden
http://www.GrafixGear.com
8 West Glen Avenue
Ridgewood, NJ 07450
USA
(201) 447-1510 voice
(201) 447-3326 fax
Speaking from a photographer's standpoint I think the preservation of
the detail and tonal info from an original is paramount [as well as the
colour of course].
What concerns me in this scenario -
when the savage [no gamut mapping] move from scanner space > RGB WS
clips actual image data [yes, it's rare we get such strong colours in
nature - but look at those strong yellows on the Fuji Lanovia test
transp' for example].
By that, I mean that the areas of high gamut colour [inside scanner
<space> but outside the WS] - which previously contained tonal
differentiation are now clipped to the same value, I've see it in
backlit leaves. If the WS is too small [as ARGB often is from a wide
gamut scanner (if I may call it that)] this tonal info is now gone -
whatever the output device. If that tonal separation had been
preserved, it could have been used in printing - with careful
targetting and the infinitely more sensitive conversion we get when
going WS > Output space.
I agree it's rare to see the difference in prints - but why not hald
all the data unclipped 'til output since we can??
Regards
NeilB
--
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