Certainly it can be done much easier. Instead of this
yth_row=(img(xcol,:)+img(xcol-1,:)+img(xcol+1,:)+img(xcol-2,:)+img(xcol+2,:))/5;
try this
yth_rows =(img(xcol-2:xcol+2,:); % this will select from 2 rows before to 2 after, so it is a matrix not a row
yth_row = mean(yth_rows); % obtain the average.
This has the advantage that you could even do it for n and the mean will work no matter how many lines you average, you could even do it in a single line, I did it in two to illustrate above, but this works as well
n = 2; % number of lines above and below to consider
yth_rows =mean(img(xcol-n:xcol+n,:)); % select from n rows above and below average.
Hope that answers the question.
