Working with image files

OpenCV provides a very simple way to load images, using imread():

import cv2
image = cv2.imread('test.jpg')

To show the image, you can use imshow(), which accepts two parameters:

• The name to write on the caption of the window that will show the image
• The image to be shown

Unfortunately, its behavior is counterintuitive, as it will not show an image unless it is followed by a call to waitKey():

cv2.imshow("Image", image)cv2.waitKey(0)

The call to waitKey() after imshow() will have two effects:

• It will actually allow OpenCV to show the image provided to imshow().
• It will wait for the specified amount of milliseconds, or until a key is pressed if the amount of milliseconds passed is <=0. It will wait indefinitely.

An image can be saved on disk using the imwrite() method, which accepts three parameters:

• The name of the file
• The image
• An optional format-dependent parameter:
...