I came across this example on how to call the function graycomatrix

>I = imread('circuit.tif'); 
>GLCM2 = graycomatrix(I,'Offset',[2 0;0 2]); 
>stats = GLCM_features1(GLCM2,0)

but I do not understand the effect of the second parameter in graycomatrix. I've read Matlab documentation but the explanation is difficult to understand.

Answer:

The second and third parameters to graycomatrix are a combined name-value pair. The value ([2 0; 0 2]) in this case is a matrix which determines the relative spacing (i.e. offset, the name of the parameter) of pixels which are examined in order to get the co-occurrence count of each value pair.

Each row in this p-by-2 matrix defines a single relative position in [row column] format. The first row of the matrix is [2 0]. This means that each pixel is compared to the pixel 2 rows down, 0 columns over (i.e. in the same column). The second row [0 2] indicates that each pixel is also compared to the pixel 0 rows away (i.e. in the same row) and 2 columns over.

Thus, each pixel is compared against two of its neighbor pixels: the pixel 2 columns to the right, and the pixel 2 rows down. The pairs formed by both of these relationships are used to increment the appropriate pixels in the output image.