Re: evaluating pantone colors with photoshop
Re: evaluating pantone colors with photoshop
- Subject: Re: evaluating pantone colors with photoshop
- From: email@hidden
- Date: Wed, 18 Sep 2002 09:40:49 EDT
In a message dated 9/17/02 6:51:57 PM, email@hidden writes:
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A prospect for one of our printers has sent some test files. Each RGB jpeg
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file when opened has 9 squares, every one a different color. The squares
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all have labels like X1, X2, X3, etc. but nothing more specific. The
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customer advises that the intent of this test is to see how well we print
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"pantone colors". When I open the file in Photoshop I am advised that the
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file contains an embedded sRGB IEC61966-2.1 profile.
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I have a few questions and hope this is an appropriate forum (as the larger
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concern is device dependent color or a referenced color space).
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1. Is it reasonable to expect decent results when files that use
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exclusively solid colors (no memory colors) arrive without much "source
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reference" info?
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In one sense the file has all the source reference info needed: the source
space. You may have concerns about the which version of Photoshop provided
these sRGB recipes for Pantone colors, as they have changed with PS versions,
or whether any of the intended colors are outside the sRGB gamut, thus will
be clipped and stand no change of being matched, and as you noted below,
there is even the possibility of the sRGB tag being incorrect. But it appears
this user is attempting a blind test, and as such takes all responsibility
for accuracy of the source file; just check that the customer is in fact
competent to be doing this, and that intent, not ignorance, is the reason for
this format.
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(If we didn't have that Photoshop era where sRGB profiles got embedded in
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everything by default, I would consider the embedded profile as
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intentional, but ...)
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2. Is there a method within Photoshop to reliably learn if "Pantone" colors
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were used? If so, can you point me to more info?
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PostScript can utilize named color callouts from the pallets of applications
like InDesign or Illustrator to make potentially more accuate matches for
library colors like Pantones, but Photoshop is all about pixels, and pixel
color values are not named in this manner. You can use the color picker to
check the values from a given Pantone library against the values in the file,
but thats rather a labor intensive method.
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(I tried a test using the color picker, and Custom Colors along with a
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Pantone book, but colors that are obviously different and show different
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Lab values indicate they are the same Pantone color.)
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One Lab value per Pantone color (at least per library, per version of
Photoshop). Nearest match may offer the same patch for differing values, if
that is what you mean. You need to know the version of Photoshop used to
prepare the file, or its a fools errand.
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3. If someone deliberately prepares a file filled with Pantone colors that
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are "out of gamut" for most process color printers - and the file is sent
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to the printer with no adjustments, what would be reasonable to expect?
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(Please - no Bill G answers like "how do you define reasonable?")
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If the Pantone color in question does not show the little three cornered icon
below it in the Solid in RGB guide, it won't be accurately achievable in
sRGB; if it does not have the little four cornered icon below it, it won't be
accurately achievable on a standard SWOP press. An intelligent customer would
have chosen their sample colors from this particular Pantone book, and made
sure both icons were present for each color chosen. I wouldn't count on it...
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FYI I have asked for more information about this file - for example whether
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it really was prepared in an sRGB workspace - but it is unlikely that I
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will get a response before the printed results are due.
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Do you care about the job, or the customer, or the work involved in this
questionable test? Set your own counterstandards: that jobs (even test files)
can't be accepted for print without being qualified as appropriately
processed. Pantone to sRGB to press without a documented workflow or a proof
is not a reasonable process.
In fact: choose your own set of Pantone vaules, place them in Photoshop 7
(where they will match current Pantone books reasonably) through a qualified
process, and print as a second section of the same test sheet. Then you can
point out the known Pantones, and show they match the book, and mention that
the match of the users side is dependant on the user's knowledge of proper
workflow.
C. David Tobie
Design Cooperative
email@hidden
Design Cooperative
email@hidden
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