I failed to understand the following code which is usefull for isolation of particular cell. especially the third line i failed to understand completely

B=bwperim(BW);
s1=I;
s1(B)=255;

where 'I' is a original image ,BW is a edge detection image. please can u expalin the code . thanks in advance. pleae concentrate especialy third line.

Answer 1

[Walter Roberson]

It sets the perimeter pixels to be white so that they show up against the rest of the image.