Hi Thomas,

thanks for your interest in the patch! Just today (see the archives), Albert Astals Cid told me that the patch passed the regression tests and he asked me about my todo list and FIXMEs. Among others, these FIXMEs contain the feature request to extend the shader to CMYK as well... my main problems are/were: I don't have test documents and I have few spare time for implementations (and a huge todo list for my free plotting package pgfplots).

I am willing to send any patches that you wish, but I suggest to await Albert's decision. If he incorporates it into the poppler master branch as-is, then you just need to pull and get the most recent changes. Any further feature requests (including CMYK support) could then be implemented as further patches- and if you have time to work on them, it would be great.

I think that my implementation can be extended to CMYK without any problems- or are there peculiarities when it comes to interpolation in CMYK color spaces? I guess it works as for RGB, so my implementation might already work without changes (as soon as the sanity check is removed). I just don't have test documents.

Best regards

Christian

Am 06.10.2010 09:33, schrieb Thomas Freitag:
 Hi Christian!

Sorry, I just subscribed to the poppler mailing list, so I didn't get Your patch and haven't seen the complete discussion. As far as I understand, You speed up matrix and triangle patch shadings, but only with RGB colorspaces. I would be interested in having that at least for CMYK, too, and I would be able to test that. So can You send me the patch and a hint what I should do to have it in CMYK? In the past I speed that up in increasing the gouraudColorDelta value, which also gave sufficient results, but Your solution seems to be better.

Best regards,
Thomas

Am 05.10.2010 22:59, schrieb Albert Astals Cid:
A Dijous, 15 de juliol de 2010, Christian Feuersaenger va escriure:
Dear poppler developers,

hereby I propose a new patch for a high quality, fast gouraud
shader for
triangle shadings.

The patch provides
- scalable triangle shadings (in contrast to the old approach),
- correct shading, no approximation using flat triangles,
- greatly (!) improved rendering speed,
- support for opacity (in contrast to the previous approach).

This patch is relative to the master branch,
git show poppler-0.14.0-91-g31ac578 .

It is unrelated to my previous patch proposals concerning shadings;
the
other patch proposal (my mail several weeks ago) is still important
and
relevant. The patch in this mail is independent and does not
include my
previous patch proposals.

I tested the new patch with pdftoppm and with the xpdf-poppler fork of
Rogerio Brito; it appears to work reliable. I tested
- matrix shadings and triangle patch shadings (Types 4 and 5),
- degenerated triangles,
- clipping,
- opacity,
- RGB color spaces.

The implementation now supports these shadings on a display driver
level
and is implemented directly in the splash device (using scanline
sweeps).

I've been defensive: I have no test cases for other color spaces and I
have no test data for non-parametric shadings. Consequently, I
disabled
the shader for these cases; it will fall back to the existing
solutions
(approximate shading by means of many flat triangles).

I hope you find my patch proposal useful. I believe it is worthy of
being part of libpoppler.
Do you have a pdf where we can see the improvement this patch gives?

Albert

Thanks,

Christian
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