MATLAB: Moving ROIs within images and across images

digital image processingimageimage analysisimage processingImage Processing ToolboxMATLABsubplot

I have a code where I read in two images and display it side-by-side. I draw a region of interest within the first image, and the region is automatically shown on the second image. When I move the rectangle to another region within the first image, only that rectangle moves (not the second image's rectangle). How can I fix this so that when I move the first rectangle, the second move moves to the same position as well.
What I have now
% Read images
I = imread('cameraman.tif');
I2 = imread('cameraman.tif');
% plot image 1 & draw a rectangular ROI on images
subplot(1,2,1); imshow(I);
roi = drawrectangle('LineWidth',2,'Color','white');
subplot(1,2,2); imshow(I2);
roi2 = drawrectangle(gca,'Position',roi.Position);
% set up listeners for ROI moving events
addlistener(roi,'MovingROI',@allevents);
addlistener(roi,'ROIMoved',@allevents);
% allevents callback function displays the previous position & the current position of the ROI
function allevents(~,evt)
    evname = evt.EventName;
    switch(evname)
        case{'MovingROI'}
            disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moving current position: ' mat2str(evt.CurrentPosition)]);
        case{'ROIMoved'}
            disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moved current position: ' mat2str(evt.CurrentPosition)]);
    end
end

Best Answer

Currently, your event lister function is just priting the values. You need to set the position too. Try following code
% Read images

I = imread('cameraman.tif');
I2 = imread('cameraman.tif');
% plot image 1 & draw a rectangular ROI on images

subplot(1,2,1); imshow(I);
roi = drawrectangle('LineWidth',2,'Color','white');
subplot(1,2,2); imshow(I2);
roi2 = drawrectangle(gca,'Position',roi.Position);
% set up listeners for ROI moving events
addlistener(roi,'MovingROI',@(r1,evt) allevents(r1,evt,roi2));
addlistener(roi,'ROIMoved',@(r1,evt) allevents(r1,evt,roi2));
% allevents callback function displays the previous position & the current position of the ROI
function allevents(roi1,evt,roi2)
    evname = evt.EventName;
    roi2.Position = roi1.Position;
    switch(evname)
        case{'MovingROI'}
            disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moving current position: ' mat2str(evt.CurrentPosition)]);
        case{'ROIMoved'}
            disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);
            disp(['ROI moved current position: ' mat2str(evt.CurrentPosition)]);
    end
end
Or a simpler solution using linkprop()
% Read images
I = imread('cameraman.tif');
I2 = imread('cameraman.tif');
% plot image 1 & draw a rectangular ROI on images
subplot(1,2,1); imshow(I);
roi = drawrectangle('LineWidth',2,'Color','white');
subplot(1,2,2); imshow(I2);
roi2 = drawrectangle(gca,'Position',roi.Position);
linkprop([roi, roi2], 'Position')
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