opencv-python实例系列一-摄像头图片视频操作

谁践踏了优雅 2022-01-21 03:23 365阅读 0赞

### 文章目录 ###

*   *  1、加载一张图片，并且在窗口中显示
     *  2、BGR转化为灰度图片
     *  3、调用摄像头并保存为视频
     *  4、调用摄像头并在窗口中显示

## 1、加载一张图片，并且在窗口中显示 ##

import cv2
    
    img = cv2.imread('北京.jpg') # 导入图片
    
    # cv2.namedWindow('Image')
    # cv2.imshow('Image', img)
    cv2.imshow('my image', img)
    cv2.waitKey(0) # 不加这一条会无响应，这也太奇怪了，直接给我卡死了
    cv2.destroyAllWindows()

打印img的类型，是numpy的数组  
![在这里插入图片描述][20190607222659515.png]

## 2、BGR转化为灰度图片 ##

import cv2
    
    img = cv2.imread('北京.jpg')
    img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    cv2.imwrite('北京.png', img)
    cv2.imshow('Image', img)
    cv2.waitKey()
    cv2.destroyWindow("Image")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70]  
在pycharm中查看相关的方法，有各种图片转化的模式。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70 1]

## 3、调用摄像头并保存为视频 ##

调用VideoCapture类  
可以设置帧率  
可以设置图片的大小  
设置拍摄的时长：通过计算帧来实现  
cameraCapture.read()返回两个参数，一是否成功，二图片frame  
打印frame类型  
![在这里插入图片描述][20190607225140356.png]

import cv2
    
    cameraCapture = cv2.VideoCapture(0)
    fps = 30
    size = (int(cameraCapture.get(cv2.CAP_PROP_FRAME_WIDTH)),
            int(cameraCapture.get(cv2.CAP_PROP_FRAME_HEIGHT)))
    print('width={0}, height={1}'.format(
        int(cameraCapture.get(cv2.CAP_PROP_FRAME_WIDTH)),
        int(cameraCapture.get(cv2.CAP_PROP_FRAME_HEIGHT))
    ))
    
    videoWriter = cv2.VideoWriter(
        'MyOutputVid.avi', cv2.VideoWriter_fourcc('I', '4', '2', '0'),\
        fps, size
    )
    
    success, frame = cameraCapture.read()
    numFramesRemaining = 10 * fps - 1
    while success and numFramesRemaining > 0:
        videoWriter.write(frame)
        success, frame = cameraCapture.read()
        numFramesRemaining -= 1
    cameraCapture.release()

## 4、调用摄像头并在窗口中显示 ##

调用摄像头，在窗口中显示。捕获键盘和鼠标活动，例如鼠标单击退出窗口，安任意建退出。

import cv2
    
    clicked = False
    def onMouse(event, x, y, flags, param): # 鼠标触发的事件
        global clicked
        if event == cv2.EVENT_LBUTTONUP: # 左键松开
            clicked = True
        return
    
    cameraCapture = cv2.VideoCapture(0)
    cv2.namedWindow('Video')
    cv2.setMouseCallback('Video', onMouse)
    
    print("正在读取摄像头，按任意建或者左键点击退出")
    
    success, frame = cameraCapture.read()
    while success and cv2.waitKey(1) == -1 and not clicked:
        cv2.imshow('Video', frame)
        # cv2.imshow('Video2', frame) # 多个窗口
        success, frame = cameraCapture.read()
    
    cv2.destroyWindow('Video')
    cameraCapture.release()

事件对应的表  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70 2]  
书上是这么说的  
![在这里插入图片描述][20190607231336471.png]

[20190607222659515.png]: /images/20220121/2b273cc33a464510ab62d84cd86b6f24.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70]: /images/20220121/d0b570dec5e544bf91ffcbb19dd9cbb2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70 1]: /images/20220121/384b38fa84e248728de13f50b2c74f5c.png
[20190607225140356.png]: /images/20220121/150adc7a507b470488f01def33ff2cea.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dqaDI2MjIwNzUxMjc_size_16_color_FFFFFF_t_70 2]: /images/20220121/c590611f620b42c6a6dd6db3f65651b9.png
[20190607231336471.png]: /images/20220121/e0cb433b7a4340d2904af0ab25e56309.png