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Re: Photoshop 6 Color Management (Working with Epson)



<x-flowed>At 7:39 PM -0400 9/2/01, Andrew Pickens wrote:
>Some weeks ago, there was a renewed discussion in this forum on print
>fading which made reference to a paper by Barbara Vogt, "Stability Issues
>and Test Methods for Ink Jet Materials."  On p. 30, the preparation of
>test samples was described, which involved Epson 1270 and 2000P printers
>and HWM and PGPP papers. The following is an excerpt:
>
>"Due to the fact that every printer driver has its own implemented color
>management or color adjustment that always tries to optimize the print, it
>is difficult to print pure color patches. In the driver software, the
>window "no color adjustment" has to be chosen. There are problems with
>printing pure colors at all with a few of the newer printers. Further, the
>software must allow the choice of the right modus (CMYK in this case);
>also any color adjustments provided by the software itself must be
>switched off. Adobe Photoshop 6.0, for example can not be used, due to
>this fact; only the previous versions can be used. Thus, to control the
>printed target, it's recommended that a magnifying glass or a microscope
>be used to view especially the pure color patches."
>
>The concluding sentence was further amplified in subsequent text, pointing
>out that the printed color samples were microscopically examined for
>absence of contamination by dots of other colors.
>
>My question regards the penultimate sentence, "Adobe Photoshop 6.0, for
>example can not be used, due to this fact; only the previous versions can
>be used."  Can someone (e.g., Bruce Fraser, C.D. Tobie) please explain
>this statement?

The problem isn't any version of Photoshop. It's the Epson driver, 
which is an RGB driver all the way. There's simply no way to specify 
to the Epson driver that you want pure patches of C, M, Y, and K. You 
can certainly get Photoshop (any version) to hand off solid C, M, Y, 
and K to the Epson driver, but it's dollars to doughnuts that that 
isn't what will get printed. (Using Printer Color Management in 
Photoshop, with ICM/ColorSync in the driver set to Saturation 
rendering will you closer than any other method I've found with the 
Epson driver, but a loupe reveals small amounts of contamination by 
the other colors.

>
>Note that the first sentence strongly implies that the standard Epson
>driver was used, but leaves open the question of whether a RIP was also
>used.  The printed target was the familiar set of seven 10-step strips of
>CMYK/C/M/Y/R/G/B, so there seems to be no reason to believe that printing
>in CMYK was even attempted.

The only way to get solid C, M, Y and K is to use a RIP, and 
moreover, one that doesn't use Epson's screening. All the RIPs I've 
seen that use Epson screening do a conversion back to RGB somewhere 
along the line...

>
>Then, what is about Photoshop 6 that precluded its use in the printing
>process as so described?  This reminds me of the attempts last spring
>("Red Cast", "Epson Settings, "870 Driver" "Using Epson 870 Profile", et
>al.) to identify the precise effects of the numerous color options
>selectable in PS and the Epson 870/1270 driver, separately and in
>combination, which identifications were never completed.
>
Given the variations from platform to platform, it was probably an 
impossible task. But there's nothing about Photoshop 6 that makes it 
any more or less impossible than previous versions.

Bruce
-- 
bruce@pixelboyz.com
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