[Openicc] questions about Scribus and color management

[Peter Linnell]

On Wed, 2003-12-10 at 14:53, Jan-Peter Homann wrote:
> Hi List
> Kai Uwe told me, that this list is close to the scribus team.
I have started it after discussions with Sven Nuemann of the GIMP team.

The idea is a working mailing list to discuss interoperation and do
things like share profile locations etc..

> As I´m familar with DTP, color management and PDF, I have some questions 
> about the implementation under Scribus.
> 
> As I´m not a programmer, I may be use not the correct terms:

Same here. I do DTP consulting, but really I am not a programmer in the
sense that I am contributing code to Scribus, but I can follow reading
source code and understand a fair amount about building and compiling.
> 
> The Scribus Color & Imaging model
> --------------------------
> In the Adobe world, the Adobe programms are using the same technologies 
> for some basic functions like simulating correct CMYK colors via color 
> management at the screen or central color settings.
> 
> I think Adobe is using the same routines / modules in his applications.

Correct on most modern Adobe apps - exception - Pagemaker 7.0.
> 
> If Scribus has already color management implemented, why should other 
> applications not use modules from scribus ?

Mostly because the way the apps use different toolkits Qt/GTK+ etc..The
key part is lcms which does the work. That is what other applications
need to use. 
> 
> My question to the Scribus programmer: Do you think, this makes sense ?
> And if yes, can you give a short description about the scribus Color & 
> imaging model ?
> 
> - Could other applications use your CMYK color specifier ?
> - Could other applications use your routines for displaying vector 
> graphics and images with color management at the monitor ?

If they are Qt based, I would imagine yes.. Perhaps other members of the
team would answer more specifically.
> 
> PDF and color management
> -------------------------
> As I talked with some programmers, PDF is very complex format, if you 
> want it to colormatch to the screen or to a printing colorspace.
> 
> Can you explain, how color is handled for PDFs which are placed in Scribus ?

They are not color managed for previewing on screen. They are imported
and a 72 dpi png is created to speed rendering. This is mostly for
positioning purposes. Indesign and Pagemaker use the same concept. 

However, you can apply profiles and rendering intents in PDF exported
from Scribus. That is a requirement of PDF/X-3. 
> 
> How is transparency handled in in Scribus especialy, if you are 
> generating PDF/X-3 were some flattening is necessary for transparent 
> objects?

By definition PDF/X-3 is PDF 1.3 which does not support transparency. To
have transparent objects, you must enable "Use PDF 1.4 features in the
display preferences. The default is off. So the choice is one or the
other and it is displayed on-screen correctly, as well as exported
properly. 

I have test PDF's with 1.4 transparency, which display and RIP properly
on both Win2k and Macs.

> 
> 
> 
> SVG and color management
> -------------------------
> For me SVG seems to be a much better fileformat, if complex objects 
> should stay editable. Comparing it to EPS or PDF, which are now used for 
> exchangig complex objects in DTP-Workflows SVG seems for me to be the 
> better format.

It is a complex file format, but has the potential to be *the*
interchange format for vector artwork. SVG weaknesses: Fonts and text
handling. EPS can remain editable, if properly prepared. PDF has limited
editing capabilities, except with Pit Stop.


> Do you support the color management features of SVG in Scribus ?

Not on import, but SVG objects can be viewed with "soft proof" on
screen. My casual reading of the spec indicates icc colors are limited
to RGB spaces. I could be wrong there, plus there is a draft SVG-Print
standard under consideration. 
> 
> If you support color management for displaying SVG, could other 
> applications use this routines ?
> 
Not easily unless it is using Qt as a main toolkit.
> 
> General question
> ----------------
> Why not defining a Scribus imaging archtitecture, which is free for 
> other projects to use in the field of graphic arts ?
> 
That is what this list is meant to make this possible in the future. 
> 
> Last question
> ------------
> With some help from a friend, I was able to compile littleCMS under 
> MacOS X. Is it possible to compile also Scribus incl. using the color 
> management features of little CMS ?

Yes, but it is not trivial. One of our developers, Paul Johnson has
compiled Scribus natively using the Qt for Mac files, but he has said
there is much work to make it integrate better with MacOSX. 

Scribus is avaialble via Fink and is actively maintained. 

I have been truly swamped with work, but I hope to draft a short
statement of purpose why this list was started.

Peter