OpenCV处理摄像头实时流时按指定按键保存imgCanny窗口图像的实现方法问询

必改前置问题 #

先解决原有代码的运行错误：

• 删掉开头的cv2.waitKey(0)，这行会阻塞程序初始化流程
• 补充缺失的导入语句和变量定义，在cap = cv2.VideoCapture(1)之后添加以下代码：

import numpy as np
import cv2
frameWidth = 640
frameHeight = 480
font = cv2.FONT_HERSHEY_SIMPLEX
save_cnt = 0 # 保存计数，避免文件被覆盖

核心功能修改 #

在主循环的按键判断逻辑里，新增指定按键触发保存的逻辑，示例用s键作为保存触发键，你可以自行替换为其他按键。
找到原来的按键判断部分：

key = cv2.waitKey(100)

if key == 27: #kills with Esc
    break

修改为：

key = cv2.waitKey(100)
if key == 27: # 按ESC退出程序
    break
if key == ord('s'): # 按s键保存Canny窗口画面
    save_path = f"canny_capture_{save_cnt}.png"
    cv2.imwrite(save_path, imgCanny)
    print(f"画面已保存至：{save_path}")
    save_cnt += 1

逻辑说明 #

• cv2.imwrite可以直接把当前帧的imgCanny对象写入本地，和cv2.imshow展示的内容完全一致
• 保存的图片默认存放在你运行代码的同级文件夹下，文件名带递增序号，不会覆盖之前的保存结果
• 如果要更换触发按键，只需要把ord('s')里的s换成你想要的按键字符即可，比如ord('c')就是按C键保存

完整修改后可运行代码 #

import cv2
import numpy as np

cap = cv2.VideoCapture(1)
frameWidth = 640
frameHeight = 480
font = cv2.FONT_HERSHEY_SIMPLEX
save_cnt = 0

cap.set(3, frameWidth)
cap.set(4, frameHeight)

def empty(a):
    pass

cv2.namedWindow("Parameters")
cv2.resizeWindow("Parameters", 640, 240)
cv2.createTrackbar("Threshold1", "Parameters", 150, 500, empty)
cv2.createTrackbar("Threshold2", "Parameters", 255, 500, empty)

def getContours(img, imgContour):
    contours, hierarchy = cv2.findContours(img, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
    for cnt in contours:
        area = cv2.contourArea(cnt)
        approx = cv2.approxPolyDP(cnt, 0.009 * cv2.arcLength(cnt, True), True)
        n = approx.ravel()
        i = 0
        for j in n:
            if (i % 2 == 0):
                x = n[i]
                y = n[i + 1]
                string = str(int(x / 3.5)) + " " + str(int(y / 3.5))
                print(string)
                if (i == 0):
                    cv2.putText(imgContour, "", (x, y), font, 0.5, (255, 0, 0))
                else:
                    cv2.putText(imgContour, string, (x, y), font, 0.5, (0, 255, 0))
            i = i + 1
        if area > 3000:
            cv2.drawContours(imgContour, cnt, -1, (255, 0, 255), 1)
            peri = cv2.arcLength(cnt, True)

while True:
    success, img = cap.read()
    imgContour = img.copy()
    imgBlur = cv2.GaussianBlur(img, (31, 31), 1)
    imgGray = cv2.cvtColor(imgBlur, cv2.COLOR_BGR2GRAY)
    threshold1 = cv2.getTrackbarPos("Threshold1", "Parameters")
    threshold2 = cv2.getTrackbarPos("Threshold2", "Parameters")
    imgCanny = cv2.Canny(imgGray, threshold1, threshold2)
    kernel = np.ones((5, 5))
    imgDil = cv2.dilate(imgCanny, kernel, iterations=1)
    getContours(imgDil, imgContour)
    cv2.imshow("Canny", imgCanny)
    cv2.imshow("Dilated", imgContour)
    cv2.imshow("Test", imgDil)
    
    key = cv2.waitKey(100)
    if key == 27:
        break
    if key == ord('s'):
        save_path = f"canny_capture_{save_cnt}.png"
        cv2.imwrite(save_path, imgCanny)
        print(f"画面已保存至：{save_path}")
        save_cnt += 1

cap.release()
cv2.destroyAllWindows()

内容的提问来源于stack exchange，提问作者Oliver Taylor