OpenCV图像、视频的读取与基本处理

一、图像读取、显示与写出

    关于cv2.imread函数，第二个参数cv2.IMREAD_COLOR表示读取为RGB图像，cv2.IMREAD_GRAYSCALE表示读取为灰度图像

import cv2

def ShowImage(title, img):
    cv2.imshow(title, img)
    cv2.waitKey(0)          #按任意键继续
    cv2.destroyAllWindows()

img = cv2.imread('./cat.jpg', cv2.IMREAD_COLOR) #IMREAD_COLOR, IMREAD_GRAYSCALE
ShowImage('MyImage', img)
cv2.imwrite('./cat2.jpg', img)

二、视频逐帧读取与处理

import cv2

vc = cv2.VideoCapture('test.mp4')

#检查能否打开
if vc.isOpened():
    open, frame = vc.read()     #open是布尔量，表示是否读取成功；frame为第一帧图像
else:
    open = False

while open:
    ret, frame = vc.read()      #再读一帧
    if frame is None:
        break
    if ret == True:
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)  #转换成灰度图像
        cv2.imshow('result', gray)
        if cv2.waitKey(20) & 0xFF == 27:
            break

vc.release()
cv2.destroyAllWindows()