Saving "heavy" figure to PDF in MATLAB - rendering problem

Question

I generate a figure in MATLAB with large amount of elements (100000+) and want to save it into a PDF file. With zbuffer or painters renderer I've got very large and slowly opened file (over 4 Mb) - all points are in vector format. Using OpenGL renderer rasterize the figure in PDF, ok for the plot, but not good for text labels. The file size is about 150 Kb.

Try this simplified code, for example:

x=linspace(1,10,100000);
y=sin(x)+randn(size(x));
plot(x,y,'.')
set(gcf,'Renderer','zbuffer')
print -dpdf -r300 testpdf_zb
set(gcf,'Renderer','painters')
print -dpdf -r300 testpdf_pa
set(gcf,'Renderer','opengl')
print -dpdf -r300 testpdf_op

The actual figure is much more complex with several axes and different types of plots.

Is there a way to rasterize the figure, but keep text labels as vectors?

Another problem with OpenGL is that is does not work in terminal mode (-nosplash -nodesktop -nodisplay) under Mac OSX. Looks like OpenGL is not supported. I have to use terminal mode for automation. The MATLAB version I run is 2007b. Mac OSX server 10.4.

Answer 1

This is a funny one. Your problem is not Matlab, it's Ghostscript (Matlab creates PDFs by calling Ghostscript, at least on Windows). When I run

x=linspace(1,10,100000);
y=sin(x)+randn(size(x));
plot(x,y,'.')
print -dpsc2 test.ps

I've got a 2Mb PS file (all vector, of course), which when compressed became a 164Kb ZIP. One would expect to get more-or-less the same result when converting PS to PDF, but ps2pdf test.ps produced your 4Mb file!

Since you are on a Mac, you probably have Distiller. I'd give it a try — generate PS files as above, and then run them through Distiller; you should get a 150K vector PDF.

If you insist on rasterizing, I can suggest printing the figure without any axes or labels to a tiff, opening the tiff, and recreating axes and labels on top of it.