# Little triangles appearing in a Mathematica region plot with “opacity” saved in a PDF file [duplicate]

This question already has an answer here:

I am trying to produce a region plot of many functions, but Mathematica keeps showing me the little triangles when I save it as pdf. I have seen other solutions which fix the problem with PlotStyle-> color, but the problem here is the opacity of each plot.

An example:

RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}]


will produce this plot:

I saw on the internet suggestions such as:

g2 = p2 /. {Polygon[__] -> {}}


Or some functions that include

PlotPoints -> 100


But that does not work when you have two functions superposed over each other. Of course, you might suggest that I use Show then two region plots, but I don't want to deal with the opacity of each plot, and would rather have Mathematica do that for me.

Any suggestions?

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## marked as duplicate by Jens, rasher, Simon Woods, m_goldberg, Yves KlettApr 20 at 7:22

See the answers at mathematica.stackexchange.com/questions/18625/… –  Steve D Apr 20 at 4:37
If you don't want to convert to a rasterized format, then the solution to Avoiding grid lines inside filled area in RegionPlot exported as PDF appears to work fine here. That's why I would consider this a duplicate of the question linked here or in the above comment by @Steve D. –  Jens Apr 20 at 5:21

Image[RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}]]


Then you can deal with a image object instead of a graphics object

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I intend to use this for a publication, and in the case, when you zoom in, the image is not smooth enough. This won't work, sorry. Thanks for the suggestion though –  Lina Apr 20 at 3:40
@Lina Then there is another method. RegionPlot[{Cos[x^2 y] > 0, Sinc[x y + x y^2] <= 0.3}, {x, -1, 1}, {y, -1, 10}] // FullForm You can see the structure of the Graphics Object. Delete all List with 3 or 4 elements (the triangles and quadrangles), and leave the long List (the curve), then run it. –  Jason Apr 20 at 4:05
I am not sure I understand how to do that... –  Lina Apr 21 at 18:11