How to find the average colour of an image in Python with OpenCV?

In Python, using the OpenCV library to calculate the average color of an image is a straightforward process. Here are the specific steps and code examples:

Step 1: Import necessary libraries

First, install and import the OpenCV library (commonly referred to as cv2) and the numpy library for mathematical calculations.

python
import cv2
import numpy as np

Step 2: Read the image

Use the cv2.imread() function to load the image you want to process. This function requires the image file path as a parameter.

python
image = cv2.imread('path_to_your_image.jpg')

Step 3: Calculate the average color

Apply the cv2.mean() function to compute the average color across all pixels. This function returns the average values for each channel.

python
mean_color_per_channel = cv2.mean(image)

Step 4: Output the result

cv2.mean() returns a tuple containing the average values for each channel. For color images, this is typically in the form of (Blue, Green, Red, Alpha). You can simply print this result or process the values further as needed.

python
print("Average BGR values:", mean_color_per_channel)

Complete code example

Combine the steps into a single script:

python
import cv2
import numpy as np

# Image file path
image_path = 'path_to_your_image.jpg'

# Read the image
image = cv2.imread(image_path)

# Calculate the average color
mean_color_per_channel = cv2.mean(image)

# Print the result
print("Average BGR values:", mean_color_per_channel)

Note

• Ensure the correct image path.
• cv2.mean() calculates the average color across all pixels, considering every pixel in the image.
• For images with an alpha channel (e.g., PNG), the returned tuple includes the alpha value.

This method is a simple and effective approach for calculating the average color of an image, widely applied in image processing, machine learning preprocessing, and other fields.