How to plot png images with transparent background?

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Mr M.
Mr M. 2018-4-12
编辑： DGM 2022-11-3
I've just used image(), and the transparent area are shown with black colour by default, however I need white background. I tried to use set(gcf,'color','white') but this cannot help.

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Walter Roberson
Walter Roberson 2018-4-12
When you image() pass in 'AlphaData', and the transparency data. The alpha needs to be floating point (not logical) in the range 0 to 1 and the same size as the image.

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Mr M.
Mr M. 2018-4-12
OK, but how to read the png to keep transparent background?
  2 个评论
Cris LaPierre
Cris LaPierre 2019-9-11
Images get displayed in an axes. Even if the image doesn't have a background, it will at least originally display in an axes with a background color set to white. You can turn that off using
axis off
of
set(gca,'Color','none')
DGM
DGM 2022-11-3
编辑：DGM 2022-11-3
If you're trying to retain the original alpha content from the PNG file:
% read the image and its alpha
[inpict,~,alpha] = imread('peppers_rgba.png');
% show the image with the alpha from the file
image(inpict,'alphadata',im2double(alpha))
% set the axes background color if desired
set(gca,'color',[0.8 0.3 1])
If instead, your concern is how the transparent regions are visualized, then consider this example regarding display matting for transparent images.

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