How to save a figure in a MAT-file?

Question

I want to save the image in a figure directly as a 256x256 size MAT-file. However, I found that the saved MAT-file sizes were different, and when using imagesc to d

Answer 1

save doesn't do anything unexpected here. The issue is that the direction of the y-axis is inverted. In other words, the image pixels are counted from the left top whereas the plots are usually made from left bottom.

If you remove this line set(gca,'Position',[0 0 1 1]); in your code, you'll be able to see this.

---

Notice the highlighted parts in the following plots.

Spectogram plotted using the code from its documentation):

While, the imagesc(mat); gives:

---

So how to fix this?
Just reverse the y-axis direction i.e.

imagesc(mat);
set(gca,'YDir','normal');

Result: