Templates of preset directions and their associated directions. The templates correspond to directions of 45◦, 22.5◦, and 0◦, as shown by the dash lines. Each preset direction d ∈ {0,...,7} can be obtained by using the template directly, rotating the template by 90◦ clockwise (marked by †) or reflecting the template along the horizontal axis (marked by ρ)
Primary filter templates associated with direction d ∈ {0,...,7} (subject to rotation and reflection), where w1 4/16 and w2 2/16 for even strength indexes, and w1 w2 3/16 for odd strength indexes. Secondary filter templates associated with each direction (subject to reflection), where w3 2/16 and w4 1/16. The secondary filter is applied along the direction 45◦ off the corresponding primary direction d.