How to use cv2.cvtColor() method in OpenCV Python?

cv2.cvtColor() method converts the color space of an image. This function accepts two arguments:

cv2.cvtColor(image, flag)

• The first argument points to the image that you want to convert.
• The second argument is the color conversion flag. The flag has the following format:

cv2.COLOR_CURRENT2NEW

Here, CURRENT refers to the current color space. NEW points to the new color space.

For example, if you want to convert a BGR image to a grayscale, the flag will be cv2.COLOR_BGR2GRAY.

There are various flags that you can pass to the cv2.cvtColor() method, but in this tutorial, commonly used flags are explained below:

cv2.COLOR_BGR2RGB: This flag converts BGR color space to RGB color space.

cv2.COLOR_BGR2GRAY: This flag converts a BGR image to grayscale.

cv2.COLOR_BGR2HSV: If you want to convert a BGR image to HSV, then use this flag.

cv2.COLOR_BGRA2RGBA: This flag reverses the channel of an image from BGRA to RGBA.

Let's learn how to use cv2.cvtColor() method using an example:

Suppose you want to convert JPEG image to grayscale then run the below code:

import cv2

img = cv2.imread('/home/mohit/cardiff.jpg')
if img is None:
  print('Image is not present.')
else:
  img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  cv2.imshow(img)
  cv2.destroyAllWindows()
  cv2.waitKey(0)

Output