image - How to save figure with transparent background

Question

I have a plot in Matlab and am setting the background to transparent by:

set(gcf, 'Color', 'None');
set(gca, 'Color', 'None');

When I try to save the image (from the viewer), I save as a ".png", but it saves with a white background. How can I save it with the transparent background?

Answer 1

It is disappointing but, MATLAB's default saveas and print commands cannot deal with transparent things very well. You'll have to save it with some background and then convert it either through imread/imwrite or some other tool.

There are some tools that might be helpful:

• Export fig http://www.mathworks.com/matlabcentral/fileexchange/23629
• svg export http://www.mathworks.com/matlabcentral/fileexchange/7401-scalable-vector-graphics-svg-export-of-figures

I prefer vector graphics, so use svg exports when transparency is needed. If indeed you have a bitmap, use imwrite(bitmapData, 'a.png', 'png', 'transparency', backgroundColor).