[scribus-dev] lcms 2.8 and transparency flattening

[William Bader]

> From: christoph-schaefer at gmx.de
> To: scribus-dev at lists.scribus.net
> Date: Thu, 9 Jun 2016 08:42:37 +0200
> Subject: Re: [scribus-dev] lcms 2.8 and transparency flattening
> 
> Hi Leonard,
> 
> Thanks for your reply. Always appreciated!
> 
> I'm admittedly a layman here, but the reason I posted this was that one of the main problems with transparency flattening was colour management. How can we preserve and mix different colour models with transparency involved, even if we'd choose the "easy way"?
> 
> The issue may become moot once the whole world has adapted PDF/X-4, but it'll take a long time until then.
> 
> Christoph
> 
> > Gesendet: Mittwoch, 08. Juni 2016 um 09:16 Uhr
> > Von: "Leonard Rosenthol" <lrosenth at adobe.com>
> > An: "Scribus Development Mailing List" <scribus-dev at lists.scribus.net>, "Private Scribus Development List" <scribus-team at lists.scribus.net>
> > Betreff: Re: [scribus-dev] lcms 2.8 and transparency flattening
> >
> > Lcms cant help with transparency flattening.
> > 
> > There are two ways to approach that operation – the easy way or the hard way
> > 
> > Easy way: rasterize the entire page containing transparency.  For extra credit, find the smallest bounding box for complete objects that are impacted and only rasterize those, leaving everything else intact.
> > 
> > Hard way: find the exact pieces that are impacted and rebuild new objects representing those, hopefully as vectors (but rasterizing as necessary)


The poppler pdftops utility flattens transparencies the easy way by rasterizing them when the target ps level does not support transparency. If someone needs to flatten transparencies, they could theoretically run pdftops -level1sep -aaRaster yes -binary to make a flattened ps, and then ghostscript ps2pdf to convert the ps back to a pdf, but the new, flattened pdf would be rasterized and probably much larger than the original pdf.
Flattening transparencies the hard way is very hard.
William
 		 	   		  
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