Kirsch

kirsch.py

def rotate(direction, index):
            return direction[-index:] + direction[:-index]
            
def make_kernel(convolution_mask):
    k = list(convolution_mask)
    k.insert(4, 0)
    return np.array(k).reshape(3, 3)
    
def kirsch(img):
    convolution_mask = [5, -3, -3, -3, -3, -3, 5, 5]
    output = np.zeros(img.shape)
    for _ in range(8):
        c = convolve(img, make_kernel(convolution_mask))
        output = np.maximum(output, c)
        convolution_mask = rotate(convolution_mask, 1)
    return output