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From Jeremias Maerki <...@jeremias-maerki.ch>
Subject Re: How can I change the color model of an EPS image from RGB to CMYK and vice versa?
Date Fri, 17 Dec 2010 20:10:00 GMT
Olivier,
this response has a relationship with my other answer on batik-users
related to SVG: http://markmail.org/message/ffczjrvvlzxdp4bz

How do you generate EPS? With our EPSDocumentGraphics2D? If yes, the
generated colors depend on the Color instances you pass in. We don't
have a switch for either color model. It's always "mixed":

If you pass in an sRGB color, you get device-specific RGB. That is in
contrast to Batik's SVGGraphics2D. We currently don't support color
management for EPS output. All generated colors lose color profile
information and it's basically a game of chance what the final colors
will look like on the printer. We don't have the possibility, yet, to
convert the colors to a specified output profile, so any device-specific
colors will come out right. So, what happens for sRGB colors also
happens for ICC-based Color instances that use a CMYK ICC color profile.
The result will be CMYK, but possibly in the wrong color profile
depending on what printer and paper the document is printed on. Of
course, the colors will always be almost right but if high accuracy is
required some additional measures will be necessary. Basically, you'd
have to make sure that your application always uses ICC-based colors
with the color profile of the printer that the final document will be
printed on.

Long story short: we don't have a switch that magically does the right
thing.

If you need to convert some EPS between RGB and CMYK, you can look at
GhostScript. But even there, questions of required color accuracy might
arise.

As a related side-note: My experience shows that print shops often tell
you that you need to "send the document as CMYK". When asking back, it
often turns out that they don't know so much about color management.
They only learned somewhere that CMYK is better than RGB for printing
which is not wrong but also not the whole story. I'm also still learning
more and more. It's a rather complex field. Anyway, just sending "some
CMYK" doesn't solve any problem. The machines can always process "some
RGB" just as well. What's more important is to have a color-managed
workflow if color accuracy is important. In such a case you have to
approach the whole thing differently and start thinking about color with
more than just "RGB or CMYK". If color accuracy is not that important,
then you can also live with RGB.

On 17.12.2010 17:24:12 olivierk wrote:
> 
> Hi, our web app let users download dynamically generated images in different
> formats, including EPS. Some of our users download the images for printing,
> thus we would like to allow them to choose between RGB or CMYK. Is there a
> way to specify the color model when creating an EPS image? If not, what is
> the default color model and how can I change it to another? Code snippets
> are welcome :)
> 
> Thanks,
> 
> Olivier.
> -- 
> View this message in context: http://old.nabble.com/How-can-I-change-the-color-model-of-an-EPS-image-from-RGB-to-CMYK-and-vice-versa--tp30482512p30482512.html
> Sent from the Xml Graphics - General mailing list archive at Nabble.com.


HTH
Jeremias Maerki


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