Incorrect import of gradients from Adobe Illustrator PDFs

[Alex Valavanis]

Forwarded from Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=539601
Reported by: Török Edwin <email address hidden>
Date: Sun, 2 Aug 2009 10:03:01 UTC
Severity: normal
Found in version inkscape/0.46-9

When the attached file [Dragon.ai] is imported into Inkscape, the gradient on the dragon's neck appear incorrectly. This does not happen when the file is viewed in evince/xpdf/etc. The file was created in Illustrator 8, I think... it's in the old PDF format.

As pointed out by suv by email, this may well be a duplicate of bug #410846. However, it would be good to have some input from someone with more experience with old Illustrator files before marking it as a duplicate.

[Alex Valavanis (valavanisalex)]

Added a screenshot [inkscape-import-screenshot.png] showing the incorrect rendering of the gradient on the Dragon's neck in inkscape_0.48.1-2ubuntu2 in Ubuntu Natty.

[Alex Valavanis (valavanisalex)]

Added a screenshot [evince-screenshot.png] showing the correct rendering in evince.

[Alvin Penner (apenner)]

confirmed on Windows XP, Inkscape rev 10670. Unfortunately, this is not the same as Bug 530895.

[Guillermo Espertino (Gez) (gespertino-gmail)]

Hmmm. That's a known issue.
If you used blending modes in Illustrator, they won't be used in
inkscape, since we don't have per-object blending.
Notice that inkscape is displaying the right gradients (grayscale
gradients) without transparency, while the original gradients were
probably blended using screen mode.
You could move all the gradients to a new layer and use screen mode
for that layer, and it should look pretty close to the original.

If I'm right, this is not a bug, but a missing feature. And iirc it
was reported before (I just can't find the old report).
Probably this bug should be re-named to "support PDF per-object
blending modes" and moved to the wishlist.

[Guillermo Espertino (Gez) (gespertino-gmail)]

D'Oh!
Nevermind. Next time I'll read the full report better before replying.
I skipped the part that links to the exact bug report I was referring to (where I said exactly the same I did here).

/me blushes...

[Guillermo Espertino (Gez) (gespertino-gmail)]

Ok, let me try to redeem myself :-)
According to wikipedia, transparency, opacity masks AND PDF support arrived to Illustrator in version 9, so this file can't be from AI 8, but...
Prior Adobe Illustrator 10, .ai files weren't PDF compatible. So this can't be from AI9 either.
So I tried to get more information from the file. I found that Evince gives enough information: opened the file in evince, went to file, properties, and it reports that the file was created in AI CS3.
So this isn't an old AI file and it's likely to have used blending modes for those gradients.

I'm pretty sure this is a duplicate of #410846.
I insist that we should turn this report into a feature request to avoid future duplicates.
Technically it may not be a bug, but inkscape isn't showing the expected result.