Export Matlab figure as PNG?

Question

I need to automatically export figures from Matlab to PNG. My figure has a size of 600x200 px:

hFig = figure(1); 
set(hFig, 'Color', [1 1 1]); % backgroundcolor white
set(hFig, 'Position', [500 500 600 200]) % size 600x200

I tried e.g.

print -dpng image.png

but the image.png is larger than 600x200 px. Exporting the figure manually from the Figure Window GUI using the "save" button works great, I want to do exactly this automatically / from a script. Thanks for any hint!

I think the proper way to "call" the command is print(hFig, '-dpng', 'image.png') — trumpetlicks, Jun 29 '12 at 12:41
Thank you trumpetlicks, but unfortunately that ends up as 1201x901, while the matlab GUI export function gives me the 600x200 (like it should be) ): — stefan.at.kotlin, Jun 29 '12 at 12:47
@trumpetlicks: Both ways of calling `print` are equivalent. See here: http://www.mathworks.de/help/techdoc/ref/syntax.html — Florian Brucker, Jun 29 '12 at 12:57
possible duplicate of [Printing a MATLAB plot in exact dimensions on paper](http://stackoverflow.com/questions/3600945/printing-a-matlab-plot-in-exact-dimensions-on-paper) — Amro, Jun 29 '12 at 13:16

score 15 · Accepted Answer · answered Jun 29 '12 at 12:47

15

I also know the problem that figures save never look the same as on screen.

There is the saveas command which might work for you - but does also some resolution changing for me.

Only way I know is to carefully set every aspect like this:

set(gcf,'PaperUnits','inches','PaperSize',[2,6],'PaperPosition',[0 0 2 6])
print('-dpng','-r100','test')

(so paper size is 2x6" and print with 100dpi, PaperPosition is important as you will have otherwise some extra border.)

answered Jun 29 '12 at 12:47

bdecaf

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The `'PaperSize'` and `'PaperPosition'` should be `[6, 2]` and `[0 0 6 2]`, respectively, to match the original code, but otherwise this is the way to go. – Florian Brucker Jun 29 '12 at 12:56
Thank you both, that works great! The titel is shifted by some px, but that's the only difference to saving it manually and no problem. – stefan.at.kotlin Jun 29 '12 at 13:01
A follow up question on this: How can I surpress displaying the figure window? – stefan.at.kotlin Jun 29 '12 at 13:02
To answer my own follow up question: hFig = figure(1); set(hFig, 'visible', 'off'); – stefan.at.kotlin Jun 29 '12 at 13:12

Dan Becker · Answer 2 · 2012-06-29T21:54:00.830

My preferred approach for generating png plots from MATLAB is the export_fig utility available at the MATLAB file exchange.

Here's an example:

set(gcf, 'Position', [100 100 500 500], 'Color', 'w')

x=0:0.01:10;
plot(x, sin(x))
set(gca, 'FontSize', 20, 'FontName', 'Arial')

export_fig 'strip-diff-far-forward.png' -painters -nocrop

This will create a png that is 500 x 500 pixels, with 20 pixel fonts. I'm sure that internally it does the same kinds of things as in bdecaf's answer, but it is all ecapsulated in a function for you already, and has a bunch of other features too.

The drawback is that if you use the -painters renderer (which I think looks the best) you will need to have ghostscript installed. If you don't want to mess with that, you can change -painters to -opengl

Edit Now setting figure size correctly!

score 1 · Answer 3 · answered Jun 29 '12 at 13:48

Based upon bdecaf's answer:

set(gcf,'PaperUnits','inches','PaperSize',[600/96,200/96],'PaperPosition',[0 0 600/96 200/96])
print('-dpng','-r96','test')

96 is the dpi of my system. This gives me EXACTLY the same output as the save function. For Windows the dpi is typically 96, sometimes 120. Simply adjust it accordingly to your system. Note that on a beamer the DPI might again be different from your system, especially if your system has 120 DPI! 96 DPI should in general be a quite safe choice for beamers I think. Google if you need help finding out the DPI setting of your system. This answer is 99,9% based on bdecaf and Florian, so I will leave bdecaf's answer selected as the right one.

edit: 600 = horizontal image size in px, 200 = vertical image size in px

score 1 · Answer 4 · edited Feb 11 '15 at 18:37

1

Amro answer works perfectly, after you generate your figure, set PaperPositionMode to auto and the print size will be the same as screen size.

set(gcf, 'PaperPositionMode','auto')   
print('-dpng','test.png')

edited Feb 11 '15 at 18:37

NG_

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answered Feb 11 '15 at 18:18

Reza

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score 0 · Answer 5 · answered Jun 29 '12 at 13:15

0

Try:

set(hFig, 'PaperPositionMode','auto')   %# WYSIWYG
print -dpng -r0 image.png               %# at screen resolution

This tells it to produce an image the same size as it appears on screen.

answered Jun 29 '12 at 13:15

Amro

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Export Matlab figure as PNG?

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