[Scribus] Colour separations and line screen

Louis Desjardins louis_desjardins
Tue Feb 28 17:48:59 CET 2006

Frank Cox a ?crit :
> On Tue, 28 Feb 2006 12:26:53 +0100 (MET)
> Peter Nermander <m8130 at abc.se> wrote:
>>The printer should have a RIP that is suitable for the press, just find out what
>>input file format that RIP takes.
> "The printer" is us.  We own the printing press.  (Actually three, but only
> one colour machine.)  As far as I'm aware, we don't have a RIP for it, though,
> it's just a big machine in the corner.
>>You can not use the driver for your desktop printer to create suitable files.
>>Your desktop printer most likely has its own built in "RIP", so the computer
>>sends it postscript and the printer itself turns it into rasterized bitmaps
> Our workflow is as follows:
> 1) Create the document with Scribus.
> 2) Print the document from Scribus on press plates using the HP5100 printer
> that's plugged into the computer that we run Scribus on.
> 3) Put those plates in the press and start the print run.

I assume from what I read that you are able to set a linescreen from 
your printer's driver. If it works for black and white and spot colors 
jobs, then I cannot see why it wouldn't work for color seps.

You do not need to go through a PDF to print to your printer. You can 
print directly, thought the print dialog. In order to tell Scribus to 
print color seps (so each plate separately) you have to tell it "print 
separation" in the print dialog. From then, provided your printer's 
driver has a linescreen option, you should be able to achieve exactly 
what you want. I am not used to CUPS and the like but this is basically 
how it should work.

Your HP printer has its own built-in RIP (Raster Image Processor). What 
this basically does is transform the editable data from the source 
application to non-editable data so the printer can print it. What the 
printer does is actually a snap shot of your job at the very moment you 
print it. In your case, you choose to print on a material that can then 
be put on a small press. I guess it is some kind of polymer. This has to 
be screened to achieve proper offset printing.

The built-in RIP in the HP printer is not what we call a high-end RIP of 
course. It has a fixed resolution of 1200 dpi (where high-end RIPs have 
2400 and 3600 dpi... sometimes even higher) the ripped files cannot be 
saved for further use, you are limited to the options that are there and 
the screen capability must be basic (regular linescreen, regular dots, 
nothing sophisticated). But it sure is one and if you are satisfied with 
the output result on your plates, then it's ok!



> This works great for doing black-and-white and spot colour on the other two
> presses.  But now we are trying to get this third press that is supposed to do
> full colour working and are getting quite lost in the process.
>>Note that the bitmaps output from a RIP becomes HUGE so unless you really have a
>>very good reson it is best to let this part be handled by the printer.
> We have a very good reason to handle it ourselves, as you can see above.
> What exactly is a RIP?  Software?  A special printer driver, perhaps?  Or
> something else altogether?

Louis Desjardins
Mardigrafe inc.
T 514 934 1353
F 514 934 3698

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