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POMathematica: Transparent background with PNG
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copied!<p>This is most likely a bug in Mathematica 8.0.1 and maybe other versions too. Lets try the following:</p> <pre><code>Table[ Export[ "Res_" <> ToString[r] <> ".png", Rasterize[ Style[x^2 + y^2, 40], Background -> None, ImageResolution -> r ], Background -> None], {r, {20, 40, 100, 300, 400, 500, 600}} ] </code></pre> <p>This is a screen shot of what I obtain:</p> <p><img src="https://i.stack.imgur.com/PejVz.png" alt="Output"></p> <p>First thing to notice is that the last two pictures are the wrong size. This is fine to some extent since I'm satisfied with a resolution of 300 or above. Now look at this:</p> <pre><code>in = 72; G3D = Graphics3D[AspectRatio -> 0.925, Axes -> {True, True, True}, AxesEdge -> {{-1, -1}, {1, -1}, {-1, -1}}, AxesStyle -> Directive[10, Black], BaseStyle -> {FontFamily -> "Arial", FontSize -> 12}, Boxed -> False, BoxRatios -> {1, 1, 1}, LabelStyle -> Directive[Black], ImagePadding -> All, ImageSize -> 5 in, PlotRange -> All, PlotRangePadding -> None, TicksStyle -> Directive[10], ViewPoint -> {2, -2, 2}, ViewVertical -> {0, 0, 1}, Background -> None ]; surf = Show[ Graphics3D[Sphere[{0, 0, 0}, 1], Background -> None, AxesLabel -> {"x", "y", "z"}], Options[G3D] ]; fig = Show[surf, AxesStyle -> Directive[Opacity[0]], Background -> None ]; </code></pre> <p>I wish to <code>Export</code> fig as a png file with transparent background with a high resolution. Here goes my lame attempt with the always buggy Mathematica.</p> <pre><code>Table[ Export[ "Res_" <> ToString[r] <> ".png", Rasterize[fig, ImageResolution -> r, Background -> None], Background -> None ], {r, {20, 40, 100, 300, 400, 500}} ] </code></pre> <p>Here is a screenshow of a few png files.</p> <p><img src="https://i.stack.imgur.com/RPQff.png" alt="Images"></p> <p>All of them came out with the expected resolution :). But what happened to my transparent background? I have specified many times through my code <code>Background -> None</code> and yet this doesn't want to work. I looked around the web and I found this:</p> <p><a href="http://forums.wolfram.com/mathgroup/archive/2009/Feb/msg00943.html" rel="nofollow noreferrer">http://forums.wolfram.com/mathgroup/archive/2009/Feb/msg00943.html</a></p> <p>Lets use this idea.</p> <pre><code>bgImage = Image[ConstantArray[{0, 0, 0, 0}, Reverse[ImageDimensions[fig]]], ColorSpace -> "RGB"]; compImage = ImageCompose[bgImage, fig]; Table[Export["Res_" <> ToString[r] <> ".png", Rasterize[compImage, ImageResolution -> r, Background -> None], Background -> None], {r, {20, 40, 100, 300, 400, 500}}] </code></pre> <p><img src="https://i.stack.imgur.com/kSaGb.png" alt="Images"></p> <p>No backgrounds!!! :) Great. But what happened to the sizes of my images? The resolution is increasing but the image size started to decrease. I have really been messing around with this problem for too long now. I hope one of you can shed some light into this Mathematica bug and can find a hack in order to achieve a transparent background PNG with high resolution. Please mention the Mathematica version you guys are using if you find an answer.</p>

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