CODEWITHSUNDEEP
imagematlabimage-processingmatrix
Roma
Roma

Reputation: 49

Getting pixel location given its value

is it possible in matlab to get the location of a pixel(rows and column) if the value at that pixel location is known?

Thanks in advance.

Regards

Upvotes: 0

Views: 142

Answers (1)

Shai
Shai

Reputation: 114786

You can use find to get the coordinates of the pixel

[y x] = find( grayImg == val, 1 ); %// find one pixel that has intensity val

For RGB image, you need three values

[y x] = find( rgbImg(:,:,1) == r_val & rgbImg(:,:,2) == g_val & rgbImg(:,:,3) == b_val, 1 )

In case of single precision image, one might find the comparison == too strict (see, e.g. this thread). Therefore, a relaxed version can be applied:

thresh = 1e-5;
[row col] = find( abs( grayImg - val ) < thresh, 1 );

To find a pixel within thresh tolerance of val.

You may also try and find the pixel with value closest to val:

[~, lidx] = min( abs( grayImg(:) - val ) );
[row col] = ind2sub( size(grayImg), lidx );

Upvotes: 2

Related Questions