What is the fastest way to export a figure in MATLAB?

I am trying to save a figure as a .png using:

    saveas(plot_handle,'temp_figure.png','png' )

This takes about 0.8 seconds to save the figure. Is there a way I can export the figure as an image faster?

Details about what I'm trying to do:

I wrote a matlab function that produces a plot. I used the matlab compiler to compile that function as a .dll, and use it within a body of c++ code. The c++ code is essentially a GUI made with MFC, and one of the buttons calls the matlab function from the .dll. My problem is that I want the plot to show up on the GUI. The way I do this is make the matlab function save the figure as an image (png or bitmap), and then let the c++ code load that image and put it on the GUI. This works, but it is too slow because it takes 0.8 seconds to save the figure as an image.

[Walter Roberson]

You could try export_fig from the file exchange, and you could try print(), but I am not sure that either one will be faster.

Answer 1

[Yair Altman]

ScreenCapture: https://www.mathworks.com/matlabcentral/fileexchange/24323-screencapture-get-a-screen-capture-of-a-figure-frame-or-component

export_fig: https://www.mathworks.com/matlabcentral/fileexchange/23629-export-fig

Answer 2

[Jan]

See FEX: savepng for a faster method to write a PNG file.

But sharing data between processes using the slow disk as a channel is a bad idea in general. The compression of the PNG format takes time also twice: for encoding and decoding. You could get the screen's contents by

cdata = print('-RGBImage', '-r0')

But this is not fast also. I assume this is better:

function RGB = FigShot(FigH)
screen = get(groot, 'ScreenSize');
pos    = getpixelposition(FigH);
robot  = java.awt.Robot;
rect   = java.awt.Rectangle(pos(1), screen(4) - pos(4) - pos(2), pos(3), pos(4));
jImage = robot.createScreenCapture(rect);
h      = jImage.getHeight;
w      = jImage.getWidth;
pixel  = reshape(typecast(jImage.getData.getDataStorage, 'uint8'), 4, w, h);
RGB = cat(3, transpose(reshape(pixel(3, :, :), w, h)), ...
             transpose(reshape(pixel(2, :, :), w, h)), ...
             transpose(reshape(pixel(1, :, :), w, h)));
end

But I do not have a smart idea of how to get the image data to your other process.