Why figure doesn't render properly? (Opengl painters)
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I was trying to save a uint8 3D RGB matrix into png format with print(), but some pixels showed undesired shades. First try, I was saving a simple magenta rectangle (matrix 300x600x3) and the shades were on the borders: I solved setting the renderer to 'painters' (figures attached)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1154838/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1154843/image.png)
But when I tried the same on a much larger matrix (945x2556x4355) with more complex plot, even '-painters' does not work
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1154848/image.png)
Maybe here is not very clear, but in the original output I just want white and magenta pixels, while you can see here there are a lot of pink and grey shades that (I checked it) are not present in the original matrix and they don't show up when I display the image with imshow(). It's a matter of how Matlab represent the output.
I've read that Matlab can't mantain 'painters' for complex plot and adjust automatically the renderer to Opengl, so I tried to force it with several solutions:
imshow(layer1) % my matrix
s=1
fig=get(groot,'CurrentFigure');
fig.PaperUnits='points';
fig.PaperPosition=[0 0 288 144]; % I need a 600x300 pixel output
fig.Renderer='painters';
fig.RendererMode='manual';
filenamearray=["layer",s];
loopfilename=strjoin(filenamearray,'_');
axis off;
print('-painters','-dpng',loopfilename);
%%% or
print('-painters',loopfilename,"-dpng");
%%% or
print('-vector',loopfilename,"-dpng");
%%% or
print('-zbuffer',loopfilename,"-dpng");
%%% or
saveas(fig,"layer1",'png');
but they work only for the simple rectangle.
Any hint? Thanks in advance
8 个评论
Robert U
2022-10-14
Can you provide some data you are working with. Then, it would be possible to reconstruct your problem maybe, and try to fix it.
Kind regards,
Robert
回答(2 个)
Robert U
2022-10-14
Hi Simone Cotta Ramusion,
as suspected I could reproduce the smoothing at the edges. Setting smoothing off, eliminates the shaded starting and ending pixels in each line. Even I use the default renderer.
brick=zeros(300,600,3,'uint8');
brick(:,:,1)=165;
brick(:,:,2)=35;
brick(:,:,3)=99;
imshow(brick)
loops=1;
for index=1:loops
filenamearray=["face",index];
loopfilename=strjoin(filenamearray,'_');
imshow(brick);
fig=get(groot,'CurrentFigure');
fig.PaperUnits='points';
fig.PaperPosition=[0 0 288 144]; %
fig.GraphicsSmoothing = 'off';
axis off;
print(loopfilename,"-dpng");
end
16 个评论
Robert U
2022-10-21
Hi Simone Cotta Ramusino,
I found another post here: https://de.mathworks.com/matlabcentral/answers/54750-getting-better-high-resolution-images leading to the website https://matlab.fandom.com/wiki/FAQ#How_do_I_save_my_figure,_axes,_or_image?_I'm_having_trouble_with_the_built_in_MATLAB_functions.
I tried https://github.com/altmany/export_fig but without changing settings I did not succeed to remove the artifacts in the bigger brick export. Maybe, investing more effort is necessary.
Kind regards,
Robert
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