ImgSobelMorph: ImgSobelMorph is the image, which the source image has been processed by step one to step three and morphology method.
r: r is the row of the image.
c: c is the column of the image.
ImgENP is a two-dimensional array with r rows and c columns, whose value set to be zero.
For i set 2 to r-1
For j set 2 to c-1
If the sum of ImgSobelMorph (i-1:i+1, j-1:j+1) is greater than 1
Then ImgENP (i, j) set to be 1
ImgENP: ImgENP is the output image after being processed by ENPM algorithm.