[cairo] [Regression in 1.15] pdftocairo -pdf inverts image color in this PDF (#105294)

[Bryce Harrington]

On Tue, Oct 16, 2018 at 11:32:52AM +0200, Paul Menzel wrote:
> Dear Bryce,
> 
> 
> On 06/08/18 01:44, Bryce Harrington wrote:
> > Has anyone had a chance to look into this?
> 
> I do not think so.

Ah, actually on the bug report there was some subsequent discussion and
analysis.  The commenters suggest that some PDF viewers already include
code to invert CMYK for Adobe Photoshop JPEGs, so including the
workaround in Cairo double-inverts in that case.

Possibly this is just something that PDF viewers need to handle
themselves, or maybe there is a more sophisticated solution that can be
added to Cairo.  But in either case I agree we should avoid introducing
regressed behavior for 1.16, and back out the patch until someone can
dig into this deeper.

> > Is a proper fix feasible within a couple weeks (before I do the next
> > 1.15 snapshot)?  If it's not feasible and a revert has to be done,
> > would one of you like to take care of that or should I handle it?
> 
> It’d be great if you could do it. `git revert` and adding a reference to
> the bug report.

Will do.

> > I'll try to revisit this issue again before finalizing the snapshot,
> > at least to follow up with the revert if nothing else is possible.
> 
> It’d be great, if this could be done before the 1.16 release.

Thanks for reminding me about this.

Bryce