Re: colorsync-users digest, Vol 3 #132 - 14 msgs
Re: colorsync-users digest, Vol 3 #132 - 14 msgs
- Subject: Re: colorsync-users digest, Vol 3 #132 - 14 msgs
- From: David Remington <email@hidden>
- Date: Sun, 24 Mar 2002 22:08:08 -0500
The odd colors (warm, nuclear) you see when viewing a Volare capture
in various color spaces is not indicative of a problem with the color
space or the camera data. You may have heard the term "device
specific color" batted about here. RGB values do not describe a
specific color. They relate what RGB values reproduce a color on a
particular device, what values describe a color in a particular color
space, what values a particular combination of
camera/lens/lighting/camera settings/and software uses to describe a
color etc... When you open a Volare file in Adobe or ProPhoto it
looks wrong because the RGB values the camera is using to describe
colors in your scene, and the RGB values which would describe those
colors in Adobe and ProPhoto are different. When you assign a profile
which accurately defines your camera (sometimes a tall order)
Photoshop knows how to interpret its RGB values. Photoshop displays
untagged files as interpreted by your working space. After you assign
the correct profile you can convert to any working space and the
image will display correctly (at least it won't change from one space
to another). Assigning a profile does not change the files RGB
values, converting does. For an example of this open an image of a
Macbeth Color Checker (or something with easily measured color
swatches) note the RGB values Photoshop displays for a particular
patch. If this is an untagged file, or one tagged with your camera
profile, the RGB values will be those that the Volrae/Colorshop (plus
lights lens etc..) came up with. Assign another profile and note the
values. They remain unchanged but the file displays differently
because they are interpreted differently. Now convert to another
profile. Now the vales are different but the file looks the same. The
values have been changed to those that are appropriate for the gamut
of the new space. When you use curves, levels, HS etc... to correct a
untagged file at least part of the correction is a colorspace
matching correction.
Message: 3
Date: Sun, 24 Mar 2002 06:54:34 -0600
Subject: Color space and LAB?
From: Carl Maples <email@hidden>
To: <email@hidden>
<'LAB' is a good thing and it has plenty of practical uses, but serving
as a general storage format is not one of them.>
I am a photographer. I shoot a lot of jewelry and products on a Leaf Volare
for catalogs .etc. I also shoot other things on film and scan. Sometimes
making prints as large as 40 inches x 30 inches from a scanned 35mm. I am so
confused on what work space to use. Based on what I have read on the list I
have gone from AdobeRGB (which looks too 'warm') to Colormatch(which I then
read was too small) to sRGBIEC61966-2.1(which I then read was WEB only). I
use LAB for corrections only. ProPhoto and Bruce look "nuclear"! I do a
'soft' proof on an Epson 900 or 1280.
I have gone from using a profile on the raw camera files to using 'none' and
assigning in Photoshop 6.0.1 on Mac OS 9.2.2. What to do, what to do...
Which space should I use? Can I use the one that "looks best"? Also I use
'LAB' for some corrections...moving from RGB to Lab and back, making
corrections in the lightness and or the A and B channels. Is there anything
wrong with that? Moving back and forth between RGB and LAB???
Carl Maples
Check out my web site.
http://www.carlmaples.com
--
David Remington
Photographer
Digital Imaging and Photography Group
1 West
Widener Library
Cambridge, MA 02138
617-787-4032
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