How to read an image using OpenCV and read a pixel in it

Recipe Objective: How to read an image using OpenCV and read a pixel in it?

In this recipe, let us try to understand how to read an image in OpenCV.

Step 1: Importing OpenCV in python

Before we start working on OpenCV, we have to import the library in python using the following line of code.

import cv2

Step 2: Reading local image

After importing the library, we can read an image as an array in OpenCV using the built-in cv2.imread() function. This function takes two parameters which are as follows

• path: used to specify the path to the image location
• flag: used to determine how the image should be read

The flag parameter can take three values as inputs which are as follows

• cv2.IMREAD_COLOR: Coloured Image format (excludes transparency)
• cv2.IMREAD_UNCHANGED: Coloured Image format (includes transparency)
• cv2.IMREAD_GRAYSCALE: Black and white format

These parameters can also be passed as integers such as 1, -1, and 0, respectively. The default flag value is 1.

Let us try to read an image in colored format.

This is the image that we are going to read

image = cv2.imread("OpenCV_Logo.jpg", cv2.IMREAD_COLOR)

Step 3: Understanding Pixel values

If we print the image variable, we can see the pixel values of the image like this.

print(image)

    array([[[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]],

   [[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]],

   [[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]],

   ...,

   [[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]],

   [[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]],

   [[255, 255, 255],
    [255, 255, 255],
    [255, 255, 255],
    ...,
    [255, 255, 255],
    [255, 255, 255],
    [255, 255, 255]]], dtype=uint8)