MATLAB: Control image transparency with a slider- appDesigner

appdesignerimagetransparencyuislider

Hi all,
I'm trying to control de tranparency of two images using a slider.
Currently, I don't know how to do the code for this feature with a callback function with the slider.
Can anybody help me?
What I wanted, for a better understanding, is that when I'm at a max value, I only see one of the images and at the min value I only see the other. Obviously, when I move the slider I want the transparency of them to change.
Thanks in advance
JM

Best Answer

This should get you started.
Two images are plotted on top of each other. A slider is added that sets the AlphaData of the top image.
% Create a figure with two images overlayed 
fig = uifigure('HandleVisibility','on'); 
[X,cmap] = imread('corn.tif');
imshow(X,cmap);
hold on
[X2,map] = imread('peppers.png');
img2 = imshow(X2,map);
% Create a GUI with a slider that controls the 'AlphaData' value of the currently selected object
sld = uislider(fig,'Position',[50,50,300,3],'Value',1,'Limits',[0,1],...
    'ValueChangingFcn', @(sld,event)changeTransparencyFcn(sld,event,img2),...
    'BusyAction', 'cancel');
% set the slider properties such as position etc....
% % https://www.mathworks.com/help/matlab/ref/uislider.html
function changeTransparencyFcn(~, event, hobj)
% hobj is the image object handle
set(hobj,'AlphaData', event.Value)
drawnow limitrate
end
Changes made to improve answer on Feb 9, 2021.
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