Make a pause between images display in openCV

Question

I would like to show several images, making a pause in between. I have tried with waitKey, waiting the user to press ESC, but it doesn't seem to be working.

import numpy as np
import cv2

img = cv2.imread('image1.jpg',0)
cv2.imshow('image',img)


# here it should be the pause
k = cv2.waitKey(0)
if k == 27:         # wait for ESC key to exit
    cv2.destroyAllWindows()

img = cv2.imread('image2.jpg',0)
    cv2.imshow('image',img)

Any suggestion?

Thanks in advance

Answer 1

In the code you've posted, image1.jpg is displayed and waits for the user to press any key since you've used waitKey(0). The 0 indicates the program will wait until a user hits a key. You can add the number of milliseconds you want to wait before the second image is displayed in place of the 0. Once you've pressed a key, image2.jpg is read but not displayed since you do not have a waitKey after the second imshow and the program will exit.

You can try the following code. This code assumes that your "several images" are located in a folder and it displays an image, pauses for 3 seconds and displays the next.

import cv2
import os

folder_path = ''#folder path to your images

for path in os.listdir(folder_path):#loop to read one image at a time 
    imgpath = os.path.join(folder_path, path)

    frame = cv2.imread(imgpath, 1)

    cv2.imshow('Window', frame)

    key = cv2.waitKey(3000)#pauses for 3 seconds before fetching next image
    if key == 27:#if ESC is pressed, exit loop
        cv2.destroyAllWindows()
        break

Answer 2

In the waitkey() call the number is the number of milliseconds to wait for.