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How can I add transparency to an image displayed in App Designer UIAxes?

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koray beyaz
koray beyaz on 4 Oct 2017
Answered: Paul Huxel on 6 Jan 2020
I am using imread for a png image. Since AlphaData is not a property of UIAxes, I cannot use
set(h, 'AlphaData', alpha_data);
Is there any other way to add alpha values to UIAxes?

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koray beyaz
koray beyaz on 10 Oct 2017
In this particular problem I needed the image background color and the UIFigure background color to be the same. I took a png image with transparent background and figured a workaround.
[im,map,alpha]=imread('carblack.png');
im1 = im(:,:,1); %R
im2 = im(:,:,2); %G
im3 = im(:,:,3); %B
zeroel = find(~alpha) ; % Find transparent pixels (background)
im1(zeroel) = [0.81*255]; % Make those pixels a known color
im2(zeroel) = [0.87*255]; % which is the background color
im3(zeroel) = [0.91*255]; % of my UIFigure
imfinal(:,:,1) = im1;
imfinal(:,:,2) = im2;
imfinal(:,:,3) = im3;
%imshow(imfinal,'Parent',app.UIAxes)

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Answers (1)

Paul Huxel
Paul Huxel on 6 Jan 2020
AlphaData will be a property of the image that is the child of the UIAxes. It can then be set as follows:
app.UIAxes = uiaxes(uifigure); % spoof App Designer UIAxes (for demonstration)
[im,map,alpha] = imread("https://upload.wikimedia.org/wikipedia/commons/2/21/Matlab_Logo.png");
imshow(im,'Parent',app.UIAxes)
set(app.UIAxes.Children,'AlphaData',alpha)

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