Re: CompassProfile - help creating greyscale profile for RGB device.
Re: CompassProfile - help creating greyscale profile for RGB device.
- Subject: Re: CompassProfile - help creating greyscale profile for RGB device.
- From: email@hidden
- Date: Wed, 9 Apr 2003 12:08:08 EDT
In a message dated 4/8/03 8:12:39 PM, email@hidden writes:
>
We are attempting to generate a greyscale profile for our LightJet printers.
>
These are photographic printers using RGB lasers to expose photographic
>
emulsions. We print both chromogenic and real black and white materials.
>
Here
>
is the rub: Although there are several workarounds for creating grey
>
swatches,
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the software refuses to recognize the need to evaluate them as grey, so the
>
resulting profiles attempt to force color back into the image file. This
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results in extreme color posterization, and any hope of tonal integrity is
>
lost.
>
There are two possibilities here that can be confused with one another. If
you build a color profile for grayscale uses, it will attempt to blend colors
effectively to create neutral grays. This is fine for printing grayscale
iamges with color processes, but unrelated to printing with grays only.
For printing true grays only, a three dimensional Look Up Table is not
applicable, all you need is a two dimensional curve correction ofr your one
channel. You can build one of those in Photoshop's custom CMYK setup's custom
black dot gain window, and save it out as a CMYK profile, if your application
will then use the black curve from that profile effectively to print B&W
images, or you could build one in the standard curves window in Photoshop
from a 16 patch gray ramp and correction points to match in Photoshop, and
then use an action to apply that curve to all your images before printing.
C. David Tobie
Design Cooperative
email@hidden
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