OpenCV像素值取反

import  cv2  as cv
import numpy as np
# 像素取反
def get_img_info(img):
    height = img.shape[0]  # 高
    width = img.shape[1]     #宽
    channels = img.shape[2]  #通道数
    #将图像的每个像素点进行反选操作
    for row in range(height):
        for col in range(width):
            for c in range(channels):
                pv = img[row, col, c]
                img[row, col, c] = 255 - pv
    cv.imshow("reserve", img)
    cv.waitKey()
     cv.destroyAllWindows()

# 像素取反
def get_img_reserve(img):
#直接调用反选函数
   dst = cv.bitwise_not(img)
   cv.imshow("reserve",dst)
   cv.waitKey()
   cv.destroyAllWindows()