Edge detection only in a region of an image

I have an image and I want to make edge detection only on a region of this. In order to do so I have created a complex polygon using roipoly. Does anyone know how to perform edge detection on this region now? Thank you very much in advance

Answer 1

[Vishal Neelagiri]

You can use the 'edge' function to detect the edges in an image. You can also use this on the output of the 'roipoly' function. For example:

I = imread('eight.tif');
c = [222 272 300 270 221 194];
r = [21 21 75 121 121 75];
BW = roipoly(I,c,r);
figure, imshow(I)
figure, imshow(BW)

edge(BW)

You can refer to the following documentation links:

https://www.mathworks.com/help/images/ref/roipoly.html#f6-163815

https://www.mathworks.com/help/images/ref/edge.html