[poppler] Color conversion while rendering for printing

Leonard Rosenthol lrosenth at adobe.com
Mon Jun 11 21:08:31 UTC 2018

What exactly do you mean by “rendering for printing”?   Do you mean rasterizing the page to a “bitmap” OR conversion to a PDL such as Postscript OR something else?

The exactly output format plays a HUGE factor in whether color management (or any sort) is required or necessary.


From: poppler <poppler-bounces at lists.freedesktop.org> on behalf of William Bader <williambader at hotmail.com>
Date: Monday, June 11, 2018 at 7:02 AM
To: "poppler at lists.freedesktop.org" <poppler at lists.freedesktop.org>
Subject: Re: [poppler] Color conversion while rendering for printing

ghostscript had a similar issue with performance, and they added a -dUseFastColor to bypass ICC lookups.  https://www.ghostscript.com/doc/9.23/Use.htm#EPS_parameters<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ghostscript.com%2Fdoc%2F9.23%2FUse.htm%23EPS_parameters&data=02%7C01%7Clrosenth%40adobe.com%7C568c5e86e9ac4b0ade6208d5cfa404d5%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C636643225726934480&sdata=keEYP9Bj9FO796Mbqs0j8ktGGT4x3SD6yeE%2Fx7lvOnQ%3D&reserved=0>

They are also working on a fork of LCMS that is faster and thread-safe. https://www.ghostscript.com/doc/9.23/History9.htm#Version9.23<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ghostscript.com%2Fdoc%2F9.23%2FHistory9.htm%23Version9.23&data=02%7C01%7Clrosenth%40adobe.com%7C568c5e86e9ac4b0ade6208d5cfa404d5%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C636643225726934480&sdata=Y0%2B4L3yXNhQkXUD4Q039N3252ntXBlssZ5VVNQlX3Uw%3D&reserved=0>

I think that only the final application to process the file should apply the color conversion. Viewers know that they are the final application. When poppler renders a document, it doesn't know if the results will be sent to another application, to a printer that will apply its own color conversion, or to a printer that will output it directly. That might be another reason to make it optional.


From: poppler <poppler-bounces at lists.freedesktop.org> on behalf of Carlos Garcia Campos <carlosgc at gnome.org>
Sent: Monday, June 11, 2018 9:10 AM
To: poppler at lists.freedesktop.org
Subject: [poppler] Color conversion while rendering for printing


does it make sense to do color conversions using CMS while rendering
document for printing? I don't know much about CMS, I'm asking because
libcms is very very slow in some documents. When rendering individual
pages like viewers do, the slowdown is not that noticeable, but when
printing an entire document the slowdown is very annoying. I think we
could use the existing printing flag we pass when creating the GfxState
to not use CMS.

Carlos Garcia Campos
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x523E6462<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpgp.mit.edu%3A11371%2Fpks%2Flookup%3Fop%3Dget%26search%3D0x523E6462&data=02%7C01%7Clrosenth%40adobe.com%7C568c5e86e9ac4b0ade6208d5cfa404d5%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C636643225726944489&sdata=2rB%2B8UnaCfV%2BY05XMm6kJtte8A7T65D4aXlusNr4inw%3D&reserved=0>
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