Matlab app designer, overlaying images with transparency in UIAxes?

Question ---------

I am trying to display 2 overlaid images in an app within a UIAxes. I know about

imshowpair(bg,fg,'blend');

, and although it does work, it doesn`t allow me to control the transparency level.

I tried following Steve's tip , where he recommends using

f1=imshow(fig1); 
f2=imshow(fig2);

and then

set(f2,'AlphaData',alpha);

, but it doesn't work properly within a UIAxes. When I set the 'AlphaData' property, both images become transparent.

Any ideas on how can I do this? The idea would be to have a slider where the user can set the transparency of the top image interactively.

Reference code and images ----------------

    f1=imshow(ref,'Parent',app.UIAxes);
    hold on
    f2=imshow(gbT2,'Parent',app.UIAxes);
    hold off
    set(f2,'AlphaData', alpha);

Answer 1

[Chris Portal]

Using R2018a, I'm not able to reproduce this. This is the code I tried:

I = imread('cameraman.tif');
f1 = imshow(I,'Parent',app.UIAxes);
hold(app.UIAxes, 'on')

I2 = imread('pout.tif');
f2 = imshow(I2,'Parent',app.UIAxes);
hold(app.UIAxes, 'off')

set(f2,'AlphaData', 0.5);