OpenCV半小时掌握基本操作之图像基础操作

# 截取图像
img = cv2.imread("picture.jpg")
img = img[200:600, 400:1000]
cv2.imshow("cut", img)
cv2.waitKey(0)
cv2.destroyAllWindows()

cv2.split(img)

# 获取颜色通道
img = cv2.imread("picture.jpg")  # 读取图片
b, g, r = cv2.split(img)  # 分割颜色通道
print(r.shape, g.shape, b.shape)  # 调试输出

(1263, 1920) (1263, 1920) (1263, 1920)

# 单通道显示
img = cv2.imread("picture.jpg")  # 读取图片
cur_img = img.copy()  # 深拷贝
cur_img[:, :, 0] = 0  # B通道设置为0
cur_img[:, :, 1] = 0  # G通道设置为0
cv2.imshow("B channel", cur_img)  # 图片展示
cv2.waitKey(0)
cv2.destroyAllWindows() 

cv2.VideoCapture(video_path or device_index ) 

# 读取视频
vc = cv2.VideoCapture("video.mp4")

# 循环
while (True):

    # 读取一帧，ret为bool类型，指示是否成功读取这一帧
    ret, frame = vc.read()

    # 转为灰度图
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # 显示
    cv2.imshow('frame', gray)

    # 若没有按下q键，则每1毫秒显示一帧
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# 释放
vc.release()
cv2.destroyAllWindows()