Expand description
x and y dimensions are in the plane of the input. Each dimension can expand at most two in each axis per round (one positive and one negative). Adding padding at the edges to avoid boundary checks gives a maximum width of 8 + 2 * (6 + 1) = 22 for the x and y dimensions and 1 + 2 * (6 + 1) = 15 for the z and w dimensions.