[scribus] Color management conclusions (was: Re: No real CMYK black possible??)

[Jean Ghali]

Tino Schwarze-2 wrote:
> 
> On Mon, Jun 23, 2008 at 01:58:06PM -0700, Jean Ghali wrote:
> 
>> > I observed the following:
>> > - black image with ISOCoated profile looks different on screen than
>> >   black RGB image, even though they come out the same in CMYK
>> (ISOCoated
>> >   image looks a lot blacker on screen). IMO that shouldn't be the case.
>> 
>> This is perfectly expected and not an issue. The RGB and CMYK ISOCoated
>> black points are simply completely different. A RGB monitor profile will
>> usually have its black point set at L*0, the CMYK ISOCoated black point
>> is
>> around L* 14, which means that RGB black is *way* darker than ISOCoated
>> black and explain why they look different on screen. When RGB black is
>> converted to ISOCoated, well it just does not fit in the ISOCoated gamut
>> and
>> is usually mapped to ISOCoated black point ("black point compensation").
>> Which explain why RGB black looks identical to ISOCoated black after
>> conversion.
> 
> I don't agree. I've got the "simulate printer on screen" checkbox
> enabled. Therefore, what will look the same on printer should look the
> same on screen, no matter what the source profile is. It should always
> get converted source->printer->screen - that's what a soft proof is for,
> IMO. Otherwise it is useless.
> 
> 

The "simulate printer on screen" option has some issue caused directly by
changes in littlecms 1.16/1.17. lcms 1.15 works better in that respect. To
make things looks better disable black point compensation when using the
printer simulation.

Jean
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