Re: ICC DCam part 2
Re: ICC DCam part 2
- Subject: Re: ICC DCam part 2
- From: Michael Schnelle <email@hidden>
- Date: Thu, 03 May 2001 16:09:46 +0200
- Organization: Winkler Studios GmbH
Part 2 of my answer to Bjarne:
Questions ?
Why do I use three different greyscales:
- The Gretag ColorChecker is used by the most (every?) digital camera
system software for calibration an in my daily work for nothing else
because the Color-patches are like magnets for every kind of dirt an You
cant clean it without changing the color or luminance-values.
- The IT8 Scanner Testchart is of course used for making profiles.
Because it is a photographic emulsion the density and color will change
when exposing it to bright light. Thats the reason why I normally make a
new reference data with my Gretag Spectroscan before I profile my Camera.
- Both, the Gretag CC and the IT8 TC are to big and to expensive for
daily work. Thats the reason for using the Kodak Greyscale, which is
much cheaper ( about 1/10) than the other charts an it has constant
colors even from a 5 year old to a new chart. For my work I cutted the
both brightest, the medium grey an the both darkest patches out of the
chart and mounted it together to a mini-testchart for small sets.
Why is 250 the upper RGB limit for each color ?
To reproduce any colors by using ICC Profiled camera systems the Color
has to be in the range of the IT8 Testchart. If one Color or white point
has one value at 255 you dont know if the real value will be at 255 ore
may be even brighter at f.e. 265. For stupid camera softwares this is
not possible. F.e. before I calibrated my systems like above a special
bright signal-yellow with UV-parts on a package was reproduced to
brighter green-yellow. Now it will be reproduced to nearly the same
yellow like in the original.
In most of the camera softwares it is possible to embedd the profile in
the picture-file. But in my experience when the file will be opened with
different Photoshop versions at different places the colors may be
different and at some applications CM is set completely off. The
responsibility for giving out correct camera files is in my hand. Thats
why I use Logo / Gretag Batchmatcher software for profiling my camera files.
I hope my at this place described experience will help You and many
other digital photographers in finding their way through the CM-jungle.
In my case I4m still not through !
If there are more questions ore may be more simple ways to reach the
aim, tell me !
Winkler Studios GmbH
Michael Schnelle
email@hidden
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