Skeleton intersection code for

skeletonintersection.py

def getSkeletonIntersection(skeleton):
    """ Given a skeletonised image, it will give the coordinates of the intersections of the skeleton.
    
    Keyword arguments:
    skeleton -- the skeletonised image to detect the intersections of
    
    Returns: 
    List of 2-tuples (x,y) containing the intersection coordinates
    """
    # A biiiiiig list of valid intersections             2 3 4
    # These are in the format shown to the right         1 C 5
    #                                                    8 7 6 
    validIntersection = [[0,1,0,1,0,0,1,0],[0,0,1,0,1,0,0,1],[1,0,0,1,0,1,0,0],
                         [0,1,0,0,1,0,1,0],[0,0,1,0,0,1,0,1],[1,0,0,1,0,0,1,0],
                         [0,1,0,0,1,0,0,1],[1,0,1,0,0,1,0,0],[0,1,0,0,0,1,0,1],
                         [0,1,0,1,0,0,0,1],[0,1,0,1,0,1,0,0],[0,0,0,1,0,1,0,1],
                         [1,0,1,0,0,0,1,0],[1,0,1,0,1,0,0,0],[0,0,1,0,1,0,1,0],
                         [1,0,0,0,1,0,1,0],[1,0,0,1,1,1,0,0],[0,0,1,0,0,1,1,1],
                         [1,1,0,0,1,0,0,1],[0,1,1,1,0,0,1,0],[1,0,1,1,0,0,1,0],
                         [1,0,1,0,0,1,1,0],[1,0,1,1,0,1,1,0],[0,1,1,0,1,0,1,1],
                         [1,1,0,1,1,0,1,0],[1,1,0,0,1,0,1,0],[0,1,1,0,1,0,1,0],
                         [0,0,1,0,1,0,1,1],[1,0,0,1,1,0,1,0],[1,0,1,0,1,1,0,1],
                         [1,0,1,0,1,1,0,0],[1,0,1,0,1,0,0,1],[0,1,0,0,1,0,1,1],
                         [0,1,1,0,1,0,0,1],[1,1,0,1,0,0,1,0],[0,1,0,1,1,0,1,0],
                         [0,0,1,0,1,1,0,1],[1,0,1,0,0,1,0,1],[1,0,0,1,0,1,1,0],
                         [1,0,1,1,0,1,0,0]];
    image = skeleton.copy();
    image = image/255;
    intersections = list();
    for x in range(1,len(image)-1):
        for y in range(1,len(image[x])-1):
            # If we have a white pixel
            if image[x][y] == 1:
                neighbours = zs.neighbours(x,y,image);
                valid = True;
                if neighbours in validIntersection:
                    intersections.append((y,x));
    # Filter intersections to make sure we don't count them twice or ones that are very close together
    for point1 in intersections:
        for point2 in intersections:
            if (((point1[0] - point2[0])**2 + (point1[1] - point2[1])**2) < 10**2) and (point1 != point2):
                intersections.remove(point2);
    # Remove duplicates
    intersections = list(set(intersections));
    return intersections;

what is zs here on line 34 ??

Hello @JD-Hell did you know what is zs?

I also want to know what zs is in line 34.

what is zs here on line 34 ??

Apologies - zs is a library I wrote to get neighbours of a pixel. I'll see if I can find the code. I had no idea people needed this still!

def neighbours(x,y,image):
    """Return 8-neighbours of image point P1(x,y), in a clockwise order"""
    img = image
    x_1, y_1, x1, y1 = x-1, y-1, x+1, y+1;
    return [ img[x_1][y], img[x_1][y1], img[x][y1], img[x1][y1], img[x1][y], img[x1][y_1], img[x][y_1], img[x_1][y_1] ]   

Use this to get the neighbours in a clockwise order.

Hi,
I'm very new to python. I need to use the function getSkeletonIntersection(skeleton) for junction points. But when i add neighbours(x,y,image) in the file like
https://stackoverflow.com/questions/41705405/finding-intersections-of-a-skeletonised-image-in-python-opencv/41708407#41708407
as stated here- it shows UnboundLocalError: local variable referenced before assignment

when I add neighbours(x,y,image) inside of getSkeletonIntersection(skeleton) it shows
TypeError: 'list' object is not callable while trying to access a list

Could you please help here?