Question

我希望我的程序在倒计时结束后捕获图像。但在倒计时期间，我想让它向我展示现场摄像头。这是我的代码。

import cv2
import time
cam = cv2.VideoCapture(0)
countdown=3
img_counter = 0
cv2.namedWindow("test")
ret, frame = cam.read()
cv2.imshow("test", frame)
img_name = "example.png"

while countdown >0:
                time.sleep(1)
                print(countdown)
                countdown -=1
                if countdown == 0:
                    cv2.imwrite(img_name, frame)
                    print("{} written!".format(img_name))

cam.release()

cv2.destroyAllWindows()

Answer 1

您需要的是waitKey函数。它保存代码的执行，其中包含参数中指定的毫秒的数量。因此，如果您想等待3秒钟，您可以减少毫秒而不是秒，如下所示：

import numpy as np
import cv2
cap = cv2.VideoCapture(0)
seconds = 3

millis = seconds * 1000
while (millis > 0):
   # Capture frame-by-frame
   ret, frame = cap.read()
   millis = millis - 10
  # Display the resulting frame
   cv2.imshow('video recording', frame)

   if cv2.waitKey(10) & 0xFF == ord('q'):
       #this method holds execution for 10 milliseconds, which is why we 
       #reduce millis by 10
       break

 #once the while loop breaks, write img
img_name = "example.png"
cv2.imwrite(img_name, frame)
print("{} written!".format(img_name))

Python，倒计时结束后使用网络摄像头捕获图像

1 个答案: