pyramid.py 文件源码

def compute_grad(self):
        """
        precompute gradient's magnitude and angle of pyramid
            where angle is between (0, 2?)
        """

        for oct_ind, layer_ind, layer in self.enumerate():
            # todo: better kernel can be used?
            grad_x = cv2.filter2D(layer, cv2.CV_64F, np.array([[-1, 0, 1], [-2, 0, 2], [-1, 0, 1]]))
            grad_y = cv2.filter2D(layer, cv2.CV_64F, np.array([[-1, -2, -1], [0, 0, 0], [1, 2, 1]]))
            grad_mag = np.sqrt(grad_x**2 + grad_y**2)
            grad_ang = np.arctan2(grad_y, grad_x)  # each element in (-?, ?)
            grad_ang %= TAU  # (-?, 0) is moved to (?, 2*?)

            self._grad_mag[oct_ind][layer_ind] = grad_mag
            self._grad_ang[oct_ind][layer_ind] = grad_ang