halftone.py 文件源码

def gauss_kernel(size, sigma=None, size_y=None, sigma_y=None):
    """
    Generates a 2D Gaussian kernel as a numpy array
        Args:
            size (int): 1/2 the width of the kernel; total width := 2*size+1
            sigma (float): spread of the gaussian in the width direction
            size_y (int): 1/2 the height of the kernel; defaults to size
            sigma_y (float): spread of the gaussian in the height direction; defaults to sigma
        Returns:
            numpy array: normalized 2D gaussian array
    """
    size = int(size)
    if not size_y:
        size_y = size
    else:
        size_y = int(size_y)
    if not sigma:
        sigma = 0.5 * size + .1
    if not sigma_y:
        sigma_y = sigma
    x, y = np.mgrid[-size:size+1, -size_y:size_y+1]
    g = np.exp(-0.5 * (x ** 2 / sigma ** 2 + y ** 2 / sigma_y ** 2))
    return g / g.sum()