[scribus] No real CMYK black possible??

[Jan Schrewe]

Tino Schwarze schrieb am Montag, 23. Juni 2008:
> 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.

Okay, I tried your setup and I get non-matching blacks if I do try a CMYK 
black in Scribus. Then the image is real black und the CMYK black is 
something like 80% black.

If I make a RGB black (Change "Color Model" in the "Edit Color" dialogue to 
RGB) the black from scribus and the black from the RGB image match, if I 
export a PDF/X3 and viewing it in Acrobat Reader.

Did you ceck that you are using the right color model, when you craeted your 
color?

Jan