MATLAB: Update the ROI with drawrectangle change

computer visiondrawrectanglefigureguiMATLAB

Hi,

I'm trying to draw a shape (rectangle, circle etc.) to determine region of interest (ROI) in an image. When I use the drawrectangle function, I can get the corners of the first instance that the rectangle is drawn, however when I edit the rectangle on the figure (change size/position), it does not update the roi variable. How can I update the roi variable when the rectangle is altered in a script?

Code I use is below and I use R20109a;

temp = snapshot(cam1);

imshow(temp);

rect = drawrectangle;

roi = rect.Position;

Best Answer

For anyone who is wondering how to solve this issue; here is my solution that works;

This is the main code

imshow(snapshot(camL));

rect = drawrectangle;

roiL = rect.Position;

addlistener(rect,'ROIMoved',@(src, evt) roiChange(src,evt,'roiL'));

And the function

function roi = roiChange(src,evt,roi)

assignin('base',roi,evt.CurrentPosition);

end

Thanks for all the help.

Related Solutions

MATLAB: Moving ROIs within images and across images

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')

MATLAB: Changing drawellipse to drawcircle doesn’t work like I wished

I don't know why it works right now, but I changed the drawcircle/drawellipse to images.roi.Ellipse with fixed values.

%% nothing changed above
%% define ellipse
% show the image and place a circle to the right ROI
subplot(1,1,1);
imshow(image)
title('Please place circle.');
roi = images.roi.Ellipse(gca,'Center',[200,200],'Semiaxes',[Radius,Radius],'FixedAspectRatio',true,'InteractionsAllowed','translate');
waitfor(msgbox('Please adjust the circle on the original image manually and confirm it here \bfafterwards\rm with ok.','Circle correctly positioned','none',Opt));
roi = addlistener(roi,'ROIMoved',@allevents);

Now it creates a ROI that is fixed in aspect ratio and radius of the circle. You are only allowed to move the circle around your image.

Best Answer

Related Solutions

MATLAB: Moving ROIs within images and across images

MATLAB: Changing drawellipse to drawcircle doesn’t work like I wished

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