Matrix Plot as vector graphic error

Hi all, I want to plot a confusion matrix using imshow(), and everything works fine. However, if I want to export that figure into an eps or svg vector graphic it turns out to look some kind of interpolated

I already figured out that Matlab is somehow trying to upscale the image with interpolation and that the attribute 'ImshowInitialMagnification' for iptsetpref() should help. I tried things like

imshow(ConfusionMatrix);
iptsetpref('ImshowInitialMagnification',100);

but unfortunately that didn't help. It looks fine if I upscale the Matrix by myself

bigArray = imresize(smallArray, 3.456, 'nearest');

but that would kill my ticks as these are indeed for each pixel, so that the original array is actually a 12x12 matrix. Thanks for your help. Best wishes Elias