[scribus] No real CMYK black possible??

[Tino Schwarze]

On Mon, Jun 23, 2008 at 12:29:46AM +0200, Jan Schrewe wrote:

> > > > The file will go to an offset print shop[1]. They demand PDF/X3 with
> > > > ISOCoated v2 profile which is what I will provide. I fiddled around
> > > > with gs and cinepaint to check CMYK values and it doesn't look good at
> > > > all (there's no black any more in the files converted using tifficc in
> > > > final PDF/X3 output), but I suppose this is some other glitch, maybe in
> > > > gs (8.50) or in cinepaint... which tool would allow me to check real
> > > > CMYK values in PDF output?
> > >
> > > You don't need to convert your images from RGB to CMYK before you import
> > > them into scribus. Scribus dows take care of that.
> > >
> > > The same goes for colors. As Andreas already said: Define a black in RGB
> > > and let scribus take care of the conversion. You need to make sure that
> > > you use the same input profiles for your colors and your images, though.
> >
> > In theory, yes. But my tests show that RGB-0/0-0 black as a colored
> > rectangle is different from an RGB-0/0/0 black image. Even on screen it
> > looks very different! When I export to CMYK-PDF and look at it in
> > acroread8, it also looks _very_ different. It is not just some
> > almost-indistinguishable difference, you notice it instantly. And I'm
> > not going to try to print that.
> >
> > I only use two profiles: sRGB for all RGB, ISOcoated v2 for all CMYK.
> > I only get a coherent appearance if I use a huge black image as
> > background as opposed to a color (either CMYK or RGB, I couldn't find
> > something that matched).
> >
> > Something in Scribus' RGB image -> CMYK workflow is different from it's
> > RGB color -> CMYK workflow...
> 
> Are you using the same profile for "Solid Colors" and "RGB Images" in the 
> color management settings? Scribus can apply different profiles to them. Does 
> the image have a profile embedded? Is the rendering intent the same as for 
> the colors?

I checked that, about a thousand times... I use "relative colorimetric"
everywhere. I've got sRGB for solid colors as well as images (and as
monitor pseudo-profile). There is no profile in the RGB image, Scribus
displays "sRGB IEC..." as Input profile when I look at the images tab.

If I disable "black point compensation", an image with embedded
ISOCoated profile (produced via tifficc) get's darker on screen,
everything else seems to stay the same. RGB black color and RGB black
image still doesn't match - they are visibly different.

Tino.

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