GLDM matrix's shape in example

[flora-sun-zhixin]

Should not the GLDM matrix in the example in shape of (5, 9) for 2D images? Or the 0s after size 4 are trimmed because the counts are all 0s?

As a two dimensional example, consider the following 5x5 image, with 5 discrete gray levels:

$$ \textbf{I} = \begin{bmatrix} 5 & 2 & 5 & 4 & 4\\ 3 & 3 & 3 & 1 & 3\\ 2 & 1 & 1 & 1 & 3\\ 4 & 2 & 2 & 2 & 3\\ 3 & 5 & 3 & 3 & 2 \end{bmatrix} $$

For $\alpha=0$ and $\delta = 1$, the GLDM then becomes:

$$ \textbf{P} = \begin{bmatrix} 0 & 1 & 2 & 1 \\ 1 & 2 & 3 & 0 \\ 1 & 4 & 4 & 0 \\ 1 & 2 & 0 & 0 \\ 3 & 0 & 0 & 0 \end{bmatrix} $$

[friskluft]

Yes, zero columns are truncated to save memory and reduce compute cost.