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Partially transparent markers with edges are rendered differently by agg, pdf and svg backends. #10035
Description
Bug report
Bug summary
The baseline images for the rgba_markers test (rgba_markers.{png,pdf,svg}) clearly show differences in rendering between agg, pdf and svg:
top left is the svg baseline rendered by inkview (inkscape) 0.92.2, top right is the png baseline, bottom left is the pdf baseline rendered by okular 17.08.3, bottom right is the pdf baseline rendered by gs 9.22 (gs is used by the testing framework to rasterize the pdf for image comparisons).
Code for reproduction
N/A
Actual outcome
On the right subplot, whether the central blue disk overlaps with the edge red circle depends on the backend... and, for the case of pdf, also on the renderer (so that part may possibly be a bug in eother okular or gs, but at least svg and png should not be different).
Expected outcome
All three backends should render hatching in a similar manner.
Matplotlib version
- Operating system:
- Matplotlib version: master
- Matplotlib backend (
print(matplotlib.get_backend())): - Python version:
- Jupyter version (if applicable):
- Other libraries:
Activity
QuLogic commentedon Jul 28, 2020
Copying my comment from #15051:
I don't think we set knockout groups; I think this is an implicit behaviour in PDF:
It seems that some PDF viewers render this incorrectly.
anntzer commentedon Jul 29, 2020
Actually I think pdf's behavior is nicer, but we could at least think whether having consistent behavior across the backends is a goal here. For example mplcairo's pdf output is the same as for svg (i.e. with the visible overlap). (Perhaps it's just a matter of setting
overprintto False? I haven't fully parsed the spec...)See also #13360.
github-actions commentedon Apr 28, 2023
This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!
anntzer commentedon Apr 29, 2023
The svg part has been fixed by #11105, but understanding the difference in pdf rendering by ghostscript would still be nice (or perhaps it's just a matter of passing the right flags to it).