get pixel coordination by rgb values matlab

Question

how can I get the x,y coordinates for pixels in an image by rgb values in matlab ?

for example : I've got an image that I want to locate the pixels coordinates od the black area in it..

Answer 1

If you want to find all coordinates of pixles with values (R, G, B) then

[y, x] = find(img(:,:,1)==R & img(:,:,2)==G & img(:,:,3)==B);

For black pixels choose R=0, G=0, B=0