[Scribus] CMYK image processing

pixelnate pixelnate
Tue Mar 21 20:50:47 CET 2006

Kai-Uwe Behrmann wrote:
> What are the right tools you expect an pixel editor should provide?
Well, first, I must be able to convert an image to CMYK. In that, I must 
be able to tell Gimp how I want the channels to be separated. I need to 
be able to choose which printing system I will be correcting for 
(SWOP-coated, uncoated; Toyo inks; etc.), specify dot gain, and choose 
which separation type I want to use (UCR or GCR), and specify ink 
limits. The way Photoshop does this is just about perfect.

I wanted to compare how the Gimp manages color profiles to how Photoshop 
does it, but I cannot find anywhere in the Gimp where you can specify 
which profiles to use on an image. Ideally, we should be able to specify 
default profiles for images, and whether or not Gimp should use the 
embedded profiles. Again, PS is very good here.

In the 'Image > Mode' pull down there should be an option to convert to 
a profile, any profile, from a pop-up option window. For example, if I 
am correcting an image in my default RGB space (Adobe RGB) and I want to 
convert an image to sRGB before I save it for use on the web I can do 
this. Or if I am correcting an image that will be printed on different 
types of media, I can correct it in my default CMYK space and convert 
copies of it for newsprint or 4c silkscreen.

Something that Adobe has added to Photoshop that has been very useful 
for me recently, are Spot channels. Say you have a grayscale image that 
will overprint on top of a pantone color, you can create a CMYK document 
and paste the grayscale image into the black channel. Then add a spot 
channel that will print underneath it. In this way you can set up the 
image exactly as you want it printed without having to rely on 
InDesign's transparency settings. Save this image a a single-file DCS 
and you're set. With this technique you could also add a silver ink to 
the highlights on a saw or anything else metallic. I am sure you get the 

It would also be nice to have a tool like the Selective Color tool that 
Photoshop has. The other color correction tools for use with RGB look 
good, but in the future the devs should really add the ability to use 
the cc tools on adjustment layers.

Overall, I like the Gimp, but it just isn't quite ready for print 
graphics yet. Aside from the lack of CMYK tools, it is just a slow app 
to work in. It really needs a usability expert to go through and come up 
with a better keyboard shortcut map that makes it quicker to select the 
tools in the tools box and in the pull downs and add items that don't 
have shortcuts, i.e. Select > Feather.

I hope this helps. I didn't mean to knock the Gimp, because there is a 
whole lotta goodness in there. It just needs a little more love before 
people are going to give up Photoshop for print work.

_End of line_


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