How to preserve filter effects in PDF output?

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yking
Posts: 2
Joined: Tue Aug 13, 2019 8:35 pm

How to preserve filter effects in PDF output?

Postby yking » Tue Aug 13, 2019 9:06 pm

Hello all,

I've got a problem regarding filter effects; as I'm new to using those, I'm not sure if this is a bug and suspect I'm just doing something wrong or expecting a feature that's actually not supposed to be there.

I want to use a filter effect (e.g. Blend/Multiply) and have this effect preserved upon exporting to PDF. I know that PDF cannot deal with filters, so I have the "Rasterize filter effects" checkbox ticked. However, the blend mode is still not preserved.

I have attached a simple test file: The red and green circles are on Layer 1, which has Normal Blend mode, the blue circle is on Layer 2, which has Multiply Blend mode. Moreover, the green circle has a Blur of 10. In Inkscape, everything displays as it should (i.e., the green circle is blurred and the areas where the blue circle overlaps with the red and green circles are black, see Filter_in.png). Now when I export this to PDF, the overlapping areas are not black, so the filter is not preserved (see see Filter_out.png). However, the green circle is still correctly blurred, and when choosing a lower DPI, the blue circle is visibly pixelated and thus it is clear that it is indeed rasterized - but without the filter.

I have installed Inkscape version 0.92.4. I have tried using the filter effects both for layers as above, as well as by creating filters with the filter editor and applying them to individual objects, which led to the same results. I have also tried different DPI values for the PDF output (lower ones including 90 DPI and 96 DPI), which didn't resolve the problem either.

I must miss something rather simple here, I'd be glad if anyone could enlighten me!

PS: For now I use Edit -> Make a Bitmap Copy as a fallback but I'd much rather have filter effects actually be rasterized upon PDF export.
Attachments
Filter_out.png
Filter_out.png (52.95 KiB) Viewed 116 times
Filter_in.png
Filter_in.png (44.27 KiB) Viewed 116 times
Filter.svg
(3.34 KiB) Downloaded 8 times

Moini
Posts: 3294
Joined: Mon Oct 05, 2015 10:44 am

Re: How to preserve filter effects in PDF output?

Postby Moini » Tue Aug 13, 2019 10:28 pm

I haven't tested myself, but I don't think you're missing anything here - looks like a bug to me. Can you test this with the current alpha version and report a bug if the issue persists?

https://inkscape.org/releases/master/

https://inkscape.org/report
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

yking
Posts: 2
Joined: Tue Aug 13, 2019 8:35 pm

Re: How to preserve filter effects in PDF output?

Postby yking » Wed Aug 14, 2019 11:56 pm

Thank you, I have tested this with the alpha version and the problem persists.
I have created a bug report: https://gitlab.com/inkscape/inbox/issues/771

Moini
Posts: 3294
Joined: Mon Oct 05, 2015 10:44 am

Re: How to preserve filter effects in PDF output?

Postby Moini » Thu Aug 15, 2019 7:17 am

Thanks!
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)


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