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

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Fares
Fares 2018-1-28
编辑： Yair Altman 2018-1-29
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.
  1 个评论
Walter Roberson
Walter Roberson 2018-1-28
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.

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回答（2 个）

Yair Altman
Yair Altman 2018-1-29
编辑：Yair Altman 2018-1-29
Jan
Jan 2018-1-29
编辑：Jan 2018-1-29
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.

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