Need some explanation for a line of code.

http://www.mathworks.com/matlabcentral/fileexchange/35752-finger-region-localisation/content/lee_usage.m

Can any1 tell me why in the "rgb(:,:,1) = (img - img.*edge_img);" line of code, it need to " - img.*edge_img"? what is that "img.*edge_img" mean? I try to delete the " - img.*edge_img" from that line of code, still will get the same output. So can any1 explain it to me? Thank You.

Answer 1

[Walter Roberson]

It is subtracting out the image masked by the edge image. If the edge image is all 0's then that would result in no change. If the edge image is not all 0's then possibly the changes would be subtle.