Python OpenCV: Read/Display/Write Image

 Read/Display/Write Image

• Reading, displaying and writing images are the basic to image processing and computer vision task.
• In OpenCV, three inbuilt functions are used to load, display and write the images. The inbuilt functions are:
1. imread() - helps to load image from the disk
2. imshow() - helps to display image in a window
3. imwrite() - helps to write image in the directory

Read/Display an Image

For reading the image, imread() is used. The functions takes two parameters:

imread(image, flags)

• image: first argument is the name of the image/path.
• flags: is an optional flag that lets you to specify how you want to load the image. It offers three constants:

1. IMREAD_COLOR: Loads the image in the BGR format (default)
2. IMREAD_UNCHANGED: Loads the image as (including the alpha channel if present)
3. IMREAD_GRAYSCALE : Loads the image as an grayscale format

For display the image, imshow() function is used. The function takes two parameters:

imshow(name of the window, image)

Python Code

Line 2: Import the OpenCV package

Line 4: Loads "lena.jpg" from the disk and assign to img variable

Line 6: Display the image in the window using imshow() function

Line 8: Waits for the use to press any key 

Output

Writing an Image

To write the image, imwrite() function is used. The function takes two parameters:

imwrite(filename, image)

• filename: the first argument is the filename, which must include filename extension
• image: Image that you want to save

Python Code




cv2.imwrite('lena.jpg',img)