[poppler] Migrating poppler to liblcms2 from liblcms1

Albert Astals Cid aacid at kde.org
Sun Jan 22 14:06:07 PST 2012

El Dissabte, 21 de gener de 2012, a les 22:16:00, Till Kamppeter va escriure:
> [ Please always "Reply to all", I am not subscribed. ]
> Hi,
> I only want to say that liblcms1 is not maintained any more upstream and
> has a lot of crash bugs (possible security vulnerabilities).
> The replacement is liblcms2 and to get something more reliable,
> maintained and supported, we are migrating to liblcms2 at Ubuntu:
> https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/885324

Not that it matters much to poppler what downstreams do.

> I think this migration should also be done with Poppler upstream, as
> having a reliable crash-free Poppler is more important than being 5-10 %
> faster. Most users do not perceive if their PDF rendering takes 5-10 %
> more time, but they will perceive when less crashes happen. 

I've yet to find any pdf that crashes in lcms code. Also 10% might not be alot 
in your i7 laptop, but then go to an arm core and tellme 10% is not a lot.

> Also
> security fixes will get rolled out more quickly if a library is
> maintained upstream.
> Also the color accuracy (and that is what Color Management is about) is
> much better with liblcms2.
> So I highly recommend to pass Poppler upstream to liblcms2 (and note
> that the patch does not drop the liblcms1 support).

I'm not against it, i just want someone to speak to the lcms1 devel and ask 
him if he is aware of the speed regressions in lcms2, if they are "to be 
expected" or maybe we are just using the api wrong or maybe he did not profile 
lcms2 much and it can be improved.

Actually i remember reading in his webpage that lcms2 should be much faster 
than lcms1, that's why i did the porting to lcms2 in 2010, and it was my idea 
to make it mandatory for 0.16 until i found that a pdf went from 753 msecs to 
7123 msecs in rendering. 

I will now check again what is the speed in that particular pdf lcms1 vs 


>     Till
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