finding black pixel position

I need to scan black pixel row by row on image and store (or mark) only the position of first black pixel. after store the coordinate of first black pixel, do again in another row. this process is looping but i don't know how to do this. can anyone can help me...

Answer 1

[Andrei Bobrov]

[ii,jj] = find(all(I==0,3))
[~,k] = unique(ii,'first')
ij = [ii(k) jj(k)]

[mohd]

many thanks andrei bobrov..:). its help me a lot.

[niranjan prasad]

Thanks a lot.This really works for me.