锐化：会让图片的轮廓更加明显（仔细观察效果图，原本暗的地方变更亮了）
import cv2
import numpy as np
image = cv2.imread('images/Hillary.jpg')
kerel_sharpening = np.array([[-1,-1,-1],
[-1,9,-1],
[-1,-1,-1]])
sharpened = cv2.filter2D(image,-1,kerel_sharpening)
cv2.imshow("sharpened",sharpened)
cv2.waitKey()
图片锐化
