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From Martin Jacobson <jacobson.mar...@gmail.com>
Subject Re: How can I change the color model of an SVG image from RGB to CMYK and vice versa?
Date Sun, 19 Dec 2010 17:10:42 GMT
I'm going to join this thread because I have an application that
produces SVG maps that are ultimately printed to a vitreous enamel
panel that forms part of a street sign. The app has to work in RGB
because SVG only understands RGB, but the graphic design specification
defines all colours as precise CMYK values. These CMYK values were
arrived at by experimentation with the printer, and cannot be
compromised.
As you know, most RGB values map to a range of CMYK values, depending
mostly on the amount of black (K), so there isn't a nice 1 to 1
relationship between RGB & CMYK. Is there a simple, and foolproof way
of doing the conversion? Our method at the moment is a horrendous hack
that I would blush to describe!

thanks
Martin

On 17 December 2010 21:41, Jeremias Maerki <dev@jeremias-maerki.ch> wrote:
> Olivier,
> a question for you to begin with: do you know the difference between
> calibrated and uncalibrated/device colors? I'm asking because when
> people talk RGB or CMYK they very often mean uncalibrated/device colors.
> That's not something that is useful except if you have the whole
> printing workflow fully under control. Only in this case can you work
> without color management.
>
> That said, an SVG image must always have sRGB colors (not true for
> referenced bitmap images). Any other colors are always added as
> alternatives that are taken if supported. Right now, SVG supports only
> icc-color(), i.e. ICC-based calibrated colors. That way, it is possible
> to define calibrated CMYK colors. AFAIK, SVGGraphics2D only generates
> sRGB colors right now. So even if you specify an ICC-based Paint/Color on
> the Graphics2D side, the color in SVG will end up being converted to
> sRGB through Java's color management.
>
> In the end, I believe that unless your application creates images that
> need to be in exact colors (ex. CI/CD colors from a company, spot colors) for
> a printing workflow, it doesn't make much sense to think about switching
> between color models in the context of SVG. Just use sRGB. The printer
> will then convert the sRGB to the printer's specific CMYK color space
> through one single conversion (if the calibrated colors get preserved
> through the whole workflow).
>
> If the only thing you had in mind was converting some RGB value with a
> fixed formula to CMYK (i.e. uncalibrated colors), you're better off just
> working with sRGB.
>
> http://en.wikipedia.org/wiki/Color_management
>
> HTH
>
> On 17.12.2010 17:24:34 olivierk wrote:
>>
>> Hi, our web app let users download dynamically generated images in different
>> formats, including SVG. 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 SVG 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://batik.2283329.n4.nabble.com/How-can-I-change-the-color-model-of-an-SVG-image-from-RGB-to-CMYK-and-vice-versa-tp3092769p3092769.html
>> Sent from the Batik - Users mailing list archive at Nabble.com.
>
>
>
> Jeremias Maerki
>
>
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>



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