First image processing program in Computer Vision

Introduction

We use image processing to help computers understand and change pictures. This is the first step to teach computers to see like humans.

You want to open and show a picture on your computer.

You need to change a picture to black and white.

You want to resize a photo to fit on a website.

You want to find simple details like edges or colors in a picture.

Syntax

Computer Vision

import cv2

# Load an image from file
image = cv2.imread('path_to_image.jpg')

# Show the image in a window
cv2.imshow('Image Window', image)
cv2.waitKey(0)
cv2.destroyAllWindows()

Use cv2.imread() to load an image from your computer.

cv2.imshow() opens a window to display the image. cv2.waitKey(0) waits for a key press to close the window.

Examples

This loads a color image and shows it in a window.

Computer Vision

import cv2

# Load and show a color image
image = cv2.imread('flower.jpg')
cv2.imshow('Color Image', image)
cv2.waitKey(0)
cv2.destroyAllWindows()

This loads the same image but in black and white.

Computer Vision

import cv2

# Load image in grayscale (black and white)
gray_image = cv2.imread('flower.jpg', cv2.IMREAD_GRAYSCALE)
cv2.imshow('Grayscale Image', gray_image)
cv2.waitKey(0)
cv2.destroyAllWindows()

This makes the image smaller and shows it.

Computer Vision

import cv2

# Resize image to half its size
image = cv2.imread('flower.jpg')
small_image = cv2.resize(image, (image.shape[1]//2, image.shape[0]//2))
cv2.imshow('Small Image', small_image)
cv2.waitKey(0)
cv2.destroyAllWindows()

Sample Model

This program loads a color image, changes it to black and white, shows both, and prints their sizes.

Computer Vision

import cv2

# Load an image
image = cv2.imread('flower.jpg')

# Convert to grayscale
gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Show original and grayscale images
cv2.imshow('Original Image', image)
cv2.imshow('Grayscale Image', gray_image)
cv2.waitKey(0)
cv2.destroyAllWindows()

# Print image shapes
print(f'Original image shape: {image.shape}')
print(f'Grayscale image shape: {gray_image.shape}')

Important Notes

Make sure the image file path is correct or the program will not load the image.

Color images have 3 channels (blue, green, red), grayscale has 1 channel.

Use cv2.destroyAllWindows() to close all image windows properly.

Summary

Image processing lets computers open and change pictures.

Use OpenCV functions like imread, imshow, and cvtColor to work with images.

Showing images and printing their size helps understand what the program does.