scanning in RGB vs. CMYK: a major issue here!


Andrea de Polo <andrea@...>
 

Hello everyone,

I have a CreoScitex EverSmart Supreme scanner; I have already scanned 70.000 color and b/w images at 304 dpi, 2000x3000 pixels, RGB-TIFF. Now we got the following scenario: the CreoScitex local site trainer is saying:

  • The scanner acquire the files in RGB
  • The RGB color space has more color info than CMYK
  • It is fine to acquire the files in CMYK but the CreoScitex trainer say that it is not necessary

The problem is as follow: several printers and publishers are saying that they prefer if my company provide them the files as CMYK because the files are easier to print. Also they do not care to give me the output printer type or paper kind, so I do not know which profile embed into my files. They keep say that CMYK is much better, because with the K channel I get images with more vivid colors, more details, better overall.

I am lost! Shall I indeed now go to CMYK or I can use a professional system like GretagMacbeth color profile and spectrolino to apply the proper profile to my RGB files?

Currently my files, without a proper profile look for b/W images bluish on a cromalin test and the color not proper for color images; TIA; Andrea
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Terry Wyse <terry@...>
 

on 3/28/01 4:34 AM, Andrea de Polo wrote:

Hello everyone,

I have a CreoScitex EverSmart Supreme scanner; I have already scanned
70.000 color and b/w images at 304 dpi, 2000x3000 pixels, RGB-TIFF.
Now we got the following scenario: the CreoScitex local site trainer
is saying:

The scanner acquire the files in RGB
The RGB color space has more color info than CMYK
It is fine to acquire the files in CMYK but the CreoScitex trainer
say that it is not necessary


The problem is as follow: several printers and publishers are saying
that they prefer if my company provide them the files as CMYK because
the files are easier to print. Also they do not care to give me the
output printer type or paper kind, so I do not know which profile
embed into my files. They keep say that CMYK is much better, because
with the K channel I get images with more vivid colors, more details,
better overall.
They're saying "more vivid colors, more details, better overall" ?? Well...
I suppose the argument could be made that a CMYK image will have better
shadow detail and possibly sharpness do to the addition of the K channel
("the K is the key!") but to say more vivid colors is just plain wrong in
most all cases.

I think your confusion Andrea is that it sounds to you, based on what you're
hearing, that you have an "option" to go either RGB or CMYK when providing
these files to your printer. The fact is that your images WILL end up in
CMYK at some point regardless. In the printing/prepress world, you simply
can't print RGB without a conversion to CMYK somewhere in the mix. The
question then becomes "WHEN do I convert from RGB to CMYK?".

All things being equal, I think you should consider capturing your image in
RGB from the scanner and performing as much image edits/color corrections as
you can in RGB while at the same time use Photoshop 6's very cool soft
proofing feature to preview the results in CMYK so you know what to expect
of the final results. When you think you've got it, either YOU perform the
RGB-to-CMYK transform (using an appropriate CMYK setup) or have the printer
do the conversion for you and provide you with a proof of the result (note:
give them the RGB image with an embedded profile). Either way, you will have
to know what is the "proper" CMYK setup or profile to use for this printer.
Without it, either you will convert it incorrectly or, even if they perform
the conversion, you may be looking at an incorrect soft proof during your
image editing of the RGB file.

So how do you get the correct CMYK setup?
In my opinion, the printer should either 1) provide you with an ICC profile
generated from their proof/press conditions or 2) at the very least give you
an idea of what they're expecting for UCR/GCR, total ink, dot gain and black
limit. If they can't at least give you that basic info then find somebody
else to work with.

I am lost! Shall I indeed now go to CMYK or I can use a professional
system like GretagMacbeth color profile and spectrolino to apply the
proper profile to my RGB files?
If you want to create your own profile(s), that's fine but I don't feel
anybody should have to, at their expense, create profiles for a specific
printer. If you do end up creating your own profiles (from what? a proof or
press sheets), I would NOT recommend giving these profiles to them without
compensating you for doing THEIR job. If they want to receive proper CMYK
seps from you, then they should give you the means to achieve that and if
that means they provide you with custom ICC profiles of their press
conditions, then so be it. If they can't/won't, give them the RGB and let
them take responsibility for the CMYK conversion.

Short rant:
It's high time printers get a clue and start "empowering" their customers to
give them correctly separated images. Whether it's ICC color management or
simply a proper "generic" PS CMYK setup doesn't matter. I get a bit weary of
hearing printers/prepress shops bitch and moan about the quality of the
images they're getting from their customers when they're providing them ZERO
help in improving the situation. The fact is, with "consumer" scanners
getting better/cheaper all the time and with the proliferation of digital
camera images, the number of supplied RGB images is likely to increase. So
HELP your customers get them right and they'll love you for it or you can
continue to tell them how lousy their images are and watch them take their
work to somebody who will spend some time working with them.
End of rant.

My $.03 worth (since I went a little long) :-)

Terry

_____________________________
Terence L. Wyse
PrePress Systems Specialist
All Systems Integration, Inc.
114 Cummings Park
Woburn, MA 01801
Main office:
781.935.3322 voice
781.935.6622 fax
http://www.allsystems.com
terry@allsystems.com
_____________________________