Motion detection with camera in Raspberry Pi - Mini Project: Build & Apply

Motion detection with camera

📖 Scenario: You have a Raspberry Pi with a camera module. You want to detect when something moves in front of the camera. This project will help you write a simple program to detect motion by comparing images.

🎯 Goal: Build a Python program that captures images from the Raspberry Pi camera, compares them to detect motion, and prints a message when motion is detected.

📋 What You'll Learn

Use the picamera library to capture images.

Use the PIL (Pillow) library to process images.

Compare two images to detect changes.

Print Motion detected! when movement is found.

💡 Why This Matters

🌍 Real World

Motion detection is used in home security cameras to alert owners when someone moves in front of the camera.

💼 Career

Understanding how to capture and process images on devices like Raspberry Pi is useful for jobs in IoT, embedded systems, and security technology.

1

Set up initial variables and import libraries

Import the picamera and PIL.Image libraries. Create two variables called image1_path and image2_path with values 'image1.jpg' and 'image2.jpg' respectively.

Raspberry Pi

# Import picamera and PIL.Image
# Create variables image1_path and image2_path
# Your code here

Hint

Use import picamera and from PIL import Image. Then assign the file names as strings to the variables.

2

Capture two images with the camera

Create a picamera.PiCamera() object called camera. Use camera.capture() to take two pictures saved to image1_path and image2_path.

Raspberry Pi

import picamera
from PIL import Image

image1_path = 'image1.jpg'
image2_path = 'image2.jpg'

# Create camera object and capture two images
# Your code here

Hint

Create the camera with picamera.PiCamera(). Use camera.capture() twice with the file paths.

3

Compare the two images to detect motion

Open the images from image1_path and image2_path using Image.open(). Convert them to grayscale with .convert('L'). Calculate the difference by subtracting pixel values and count how many pixels differ by more than 30. Store this count in a variable called motion_pixels.

Raspberry Pi

import picamera
from PIL import Image

image1_path = 'image1.jpg'
image2_path = 'image2.jpg'

camera = picamera.PiCamera()
camera.capture(image1_path)
camera.capture(image2_path)

# Open images, convert to grayscale, and count differing pixels
# Your code here

Hint

Use Image.open() and .convert('L') to get grayscale images. Use getdata() to get pixels. Loop through pixels and count differences over 30.

4

Print motion detection result

If motion_pixels is greater than 1000, print Motion detected!. Otherwise, print No motion detected.

Raspberry Pi

import picamera
from PIL import Image

image1_path = 'image1.jpg'
image2_path = 'image2.jpg'

camera = picamera.PiCamera()
camera.capture(image1_path)
camera.capture(image2_path)

img1 = Image.open(image1_path).convert('L')
img2 = Image.open(image2_path).convert('L')

pixels1 = list(img1.getdata())
pixels2 = list(img2.getdata())

motion_pixels = 0
for p1, p2 in zip(pixels1, pixels2):
    if abs(p1 - p2) > 30:
        motion_pixels += 1

# Print motion detection message
# Your code here

Hint

Use an if statement to check if motion_pixels is greater than 1000. Print the correct message accordingly.