MATLAB: Obtain a difference image

digital image processingimage processingMATLAB

Can any body guide me How to obtain a difference image by taking first-order horizontal differences?

diffImage = conv2(grayImage, [1, -1], 'same');

If I remember correctly, diff works across the first non-singleton dimension. So diff(A) works across columns and diff(A(1, :)) works across rows.

x = [1,2,3; 4,5,6];
diff(x, [], 1)
ans =
   3     3     3
diff(x, [], 2)
ans =
   1     1
   1     1

To crop you can use imcrop(), or simply use indexing:

croppedImage = fullImage(row1:row2, col1:col2);