Need explanation of the following MATLAB code?

x=bwperim(im); 
y(x)=255;

Where, im=Binary image of given Gray scale image and y= given gray scale image and bwperim is fuction for calcuation of perimeter.

Answer 1

[Guillaume]

What is there to not understand?

The code uses logical indexing to set the pixels of the perimeter to 255 in the grayscale image.