Re: Gray space
Re: Gray space
- Subject: Re: Gray space
- From: David Remington <email@hidden>
- Date: Thu, 21 Nov 2002 14:55:02 -0500
Jim,
The prints are to be photographed with a Leaf Volare camera and
exported as 16 bit RGB files. They will then be converted to gray
scale and edited in photoshop. Based on the volume of prints (25,000)
cost constraints dictate automated batch processing. I will record an
action in Photoshop then test it on a range of prints repeating until
it works as well as possible on the majority. I haven't worked
extensively with gray scale images and am surprised by the different
way Photoshop handles assigning and converting between profiles. For
instance when working in gray scale assigning a gray profile changes
the values, where in RGB only converting actually changes values.
Right now I'm opening in RGB, converting to gray scale (I've selected
2.2 gamma as the working space), assigning a profile that gives a
pretty good tonal match (1.8), converting to 2.2, applying a curve,
converting to 8 bit, saving a tiff (tagged 2.2), then going on to
make and save several progressively smaller jpgs. Convoluted but it's
working. Still, I need to get my head around it better. Incidentally,
I've set the exposure and tonal curve in the camera software to
approximate a 1.8 gamma curve based on reflective values from a Kodak
Q-13 gray scale. This gives me a good starting point and the gamma
spaces in Photoshop match up pretty well. It's funny though, if I
open a capture of the Q-13 and convert to gray scale spot readings
give me my capture values for a 1.8 gamma (in this case a
curve/exposure setting that hits 240 for the "A" patch, 100 "M", and
30 "B"). When I then assign the 1.8 space my values change to those
of a 2.2 space (243, 117, 44). When I then convert to 2.2 the values
are unchanged "correct" 2.2 gamma readings. See what I mean about
counterintuitive? Anyhow, I'm happy to get feedback on this.
Thanks,
David
David,
Hmm...
To me it is not clear how you are handling the capture of the images and how
you are planning to set up your workflow.
Are you using a digital camera?
Are you shooting B&W film that will be scanned?
Or are you scanning color or grayscale prints?
If you are using color images or black and white prints, how and where in
your workflow are you planning to convert the images to grayscale?
Jim Rich
--
David Remington
Collections Reformatting Photographer
Digital Imaging and Photography Group
D 40
Widener Library
Cambridge, MA 02138
617-496-9346
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