Re: Gray space
Re: Gray space
- Subject: Re: Gray space
- From: Jim Rich <email@hidden>
- Date: Thu, 21 Nov 2002 15:14:00 -0500
On 11/21/02 2:55 PM, "David Remington" <email@hidden> wrote:
David,
Now I have a better sense of what you are doing.
One option is that once you have gotten say into an Adobe working space such
as Adobe RGB 1998 is to create a grayscale profile and convert your images.
This for me is the most straight forward way to get to gray.
As for 20 % dot gain. Its not a bad place to start. If images come out too
light or dark then go up or down in increments of 5% until you feel good
about it.
Here part of a post/tip about this topic (grayscale) from the other day
relating to creating custom grayscale profiles.
<Why don9t you use Photoshop to create the GS printer profile by using a
densitometer to measure thirteen halftone dot values from the grayscale dot
gain dialog box that range from light to dark. And then if necessary tweak
the highlight and shadow target values to get what you want.>
This process would get you well on your way.
Jim Rich
>
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
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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
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