Query regarding Edge histogram descriptor

Hello All, According to standard,there are 5 types of edges i.e.horizontal,vertical,45 degree diagonal,135 degree diagonal and non directional. I have applied sobel edge detection algorithm. My question is 1) how do i identify the type of the edge whether it is horizontal/vertical? Thanks & Regards, MSA

The EHD operators are - in contrast to Sobel - asymmetric. For example, something like [-1 1 ; 1 -1] is used for diagonal edges. The intensity image is simply folded with each operators locally and the edge type is chosen by selecting the maximum output of the five operators (one for each type). If you want to use Sobel, I recommend computing the gradient and quantizing it to the four major directions (and "non-directional").