double_threshold

[james77777778]

I think task4: double_threshold has an error that we should use x, y to check the neighbors which might be a strong edge pixel.
Following is my correct version and it works.

for i in index_weak_edge_pixel:
    x = i[0]
    y = i[1]
    if(x > 0 and y > 0 and x < 511 and y < 511):
        north = (x-1, y)
        south = (x+1, y)
        east = (x, y+1)
        west = (x, y-1)
        north_east = (x-1, y+1)
        north_west = (x-1, y-1)
        south_west = (x+1, y-1)
        south_east = (x+1, y+1)
        # check if any of the 8 neighbors is a strong edge pixel
        if((strong_edge_pixel[north] > 0) or
           (strong_edge_pixel[south] > 0) or
           (strong_edge_pixel[east] > 0) or
           (strong_edge_pixel[west] > 0) or
           (strong_edge_pixel[north_east] > 0) or
           (strong_edge_pixel[north_west] > 0) or
           (strong_edge_pixel[south_west] > 0) or
           (strong_edge_pixel[south_east] > 0)):
            final_image[x][y] = 1  # classify the pixel as an edge pixel

I just notify if others want to use this code and thanks author for this great work!