Try using saveas to save the figure as an image.
These formats would contain one 'int' per pixel, even if many data points were plotted there.
I prefer PNG as JPG could contain artifacts.
Plotting with a marker '.'
>> numpts=1e5; iii=1:numpts; plot( sin(3*pi*iii/numpts)+rand(size(iii)),'.') >> saveas(gcf,'t1.png','png'); saveas(gcf,'t1.pdf','pdf')
t1.pdf ~= 1.5Mb t1.png = 86k
Plotting with lines - the PDF is able to compress some how. t1.pdf = 109k t1.png = 27k
Also, I recall that with older matlabs, the PNG resolution was greater if figure was large on the screen. With 2014b doesn't seem to be that way.