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

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?

[koray beyaz]

 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)

[DGM]

It's not clear whether this was relevant, but:

https://www.mathworks.com/matlabcentral/answers/1734305-how-to-show-an-image-with-transparent-background-using-uiimage

That covers uiimage() objects in a uifigure, image() objects, and direct compositing approaches.

Answer 1

[Paul Huxel]

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)

Answer 2

[Image Analyst]

See Steve's blogs:

How to overlay a foreground image over a background image? - MATLAB Answers - MATLAB Central

Image overlay using transparency | Steve on Image Processing