Algorithm 1 Projection of each pixel.

Input: Original image A; Output: $D_0(i,j),D_{45}(i,j),D_{90}(i,j),D_{135}(i,j)$ for each $(i,j)$ in image A 1:initial $i=0$ and $j=0$; 2:for each $(i,j)\in A$ do 3:     Compute $G_0(i,j)$, $G_{90}(i,j)$ with Equations (2) and (3); 4:     Compute $D_0(i,j),D_{45}(i,j),D_{90}(i,j),D_{135}(i,j)$ with Equations (12)–(15); 5:end for 6:return$D_0(i,j),D_{45}(i,j),D_{90}(i,j),D_{135}(i,j)$;