Transparency rendering problems in Mathematica 10 (Mac)

Question

Bug introduced in 10.0.0 and fixed in 10.0.1

For some weird reason, they apparently changed the styling of contours in ContourPlot for 10.0. Here is a comparison of the results for V9 and V10 (first 9, then 10):

ContourPlot[Sin[x y], {x, 0, 3}, {y, 0, 3}, 
    ContourShading -> None,  ContourStyle -> {{Red, Thickness[0.008]}}]

Mathematica 9 output Version 9

Mathematica 10 output Version 10

Firstly, can I override the coloring? I would like to keep the solid colors that were in V9. And secondly, where do those dark spots come from? Is this a bug?

Edit: yes, this does look like a bug. The dark spots are only visible in the Mac version.

Interestingly enough, for about half a second after the output appears, what I see on the screen is similar to what Export produces (shown below). The only difference is that the lines are thinner in the exported .png (another bug?). After those 0.5 seconds, another level of transparency kicks in and I see what is shown in the top picture below.

ContourPlot[Sin[x y], {x, 0, 3}, {y, 0, 3}, 
    Contours -> {.9}, ContourShading -> None, 
    ContourStyle -> {{Red, Thickness[0.17]}}]

enter image description here <- What I see. <- What Export produces.

@YiWang you meant Classic? It's okay but it adds a strange blue frame even with `Frame->None" added. And the dark spots are still suspicious. — Alex Bogatskiy, Jul 10 '14 at 07:05
it sounds like it I assume as I do not see the result you show on my windows 7 system. — Nasser, Jul 10 '14 at 07:25
ContourStyle -> {{Red,Opacity[1],Thickness[0.008]}} gives the same contour line colors as in v9. — kglr, Jul 10 '14 at 07:25
@kguler installed the Windows version... yep, no spots there. — Alex Bogatskiy, Jul 10 '14 at 09:38
Here is a wild guess: Might these spots come from overlapping ends of line segments (caps), and they become darker due to additive effects and the transparency? See this answer: http://mathematica.stackexchange.com/a/5406/58 — Thomas, Jul 10 '14 at 10:31
@Thomas interesting... If that's the case, then I guess there is no simple way to fix this. — Alex Bogatskiy, Jul 10 '14 at 10:39
@level1807 Presumably (but I don't know) rendering in general (and of transparent objects in particular) uses OS functionality and is therefore platform specific, which might explain why it occurs on Macs but not Windows. — Thomas, Jul 10 '14 at 10:50
I can reproduce the dots you see under Linux. Also, I think that @Thomas is correct. Try this: Contours -> {.9}, ContourShading -> None, ContourStyle -> {{Red,Thickness[0.1]}} — sebhofer, Jul 10 '14 at 11:30
@sebhofer there is even more to this problem, as my experiment with Export shows (see the edited post). — Alex Bogatskiy, Jul 10 '14 at 11:38
Interesting: They fixed the overlap in 10.0.1, and in 10.0.2 they changed the Opacity[0.5] to Opacity[1]. — Michael E2, Aug 09 '15 at 12:08

score 6 · Accepted Answer · edited Apr 13 '17 at 12:55

6

I propose two possible solutions:

Turn off transparency by including Opacity[1] in the CountourStyle
Use CapForm["Butt"] to prevent the line caps from overlapping. With this solution you can keep transparency on, and the result will look like:

With CapForm["Butt"] theoretically there can still be a slight misalignment, or crack between the lines, but this is unlikely to be visible in practice.

Edit: Another possible solution is adding the option Method -> {"TransparentPolygonMesh" -> True}, as described here. I don't know what this does exactly.

edited Apr 13 '17 at 12:55

Community

1

answered Jul 10 '14 at 13:40

Szabolcs

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Wow, this is a pretty neat solution. Is there a way to tell if they actually use "Butt" automatically in the Windows version? Or anything else.. – Alex Bogatskiy Jul 10 '14 at 15:44
@level1807 You could try all possible values in the Windows version and see if it makes a difference. If it does not make a difference, then the most likely explanation is that lines that are specified together, as a single Line primitive, are also rendered together by Windows, and transparency is added only after all lines have been rendered. I would compare Graphics@{Thickness[0.2], Opacity[0.5], Line[{{{-1, 0}, {1, 0}}, {{0, -1}, {0, 1}}}]} with Graphics@{Thickness[0.2], Opacity[0.5], Line[{{-1, 0}, {1, 0}}], Line[{{0, -1}, {0, 1}}]} on both Windows and Mac. – Szabolcs Jul 10 '14 at 15:54
@level1807 See my update. – Szabolcs Jul 10 '14 at 16:00

score 3 · Answer 2 · answered Jul 11 '14 at 07:36

3

I don't know if this help or not but here is what I got for you.

ContourPlot[Sin[x y], {x, 0, 3}, {y, 0, 3}, ContourShading -> None, 
 ContourStyle -> {{Red, Thickness[0.008]}}, PlotTheme -> None]

enter image description here

answered Jul 11 '14 at 07:36

Basheer Algohi

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Wow, I didn't think this is None =) Apparently Opacity[1] already gave the save effect, but thanks. This question has now transformed into a discussion of rendering bugs. – Alex Bogatskiy Jul 11 '14 at 16:01

Transparency rendering problems in Mathematica 10 (Mac)

2 Answers2