how to track boundary in matlab

Question

piku mandal 2018-10-4

编辑： JSC 2018-10-4

how to track boundary of the red underlined image?

KSSV 2018-10-4

Attach original image...

Answer 1

JSC 2018-10-4

编辑：JSC 2018-10-4

First you should read in the image:

Image=imread('03.png');

Then you can do a color conversion by thresholding on the color channels:

RedChannel=Image(:,:,1);
GreenChannel=Image(:,:,2);
%convert red areas to 1 and others to 0
Image_BW = (RedChannel>200).* (GreenChannel<100);

There is also an app for color thresholding: https://de.mathworks.com/help/images/image-segmentation-using-the-color-thesholder-app.html

Finally you can get a cell array of the boundary pixels with

B=bwboundaries(Image_BW);

and plot the result:

figure(1)
clf
imshow(Image_BW)
%Get and plot boundaries
for i=1:size(B)
   Bound=B{i};
   hold on
   plot(Bound(:,2),Bound(:,1),'g-')
end