OpenCV-Python Exercise

What you'll learn

• How to install and set up OpenCV with Python
• Reading and displaying images using OpenCV
• Capturing and playing video files
• Working with webcam input in real-time
• Basic image and video processing techniques

Introduction

This exercise will guide you through the basics of using OpenCV with Python for image and video processing.

Access the exercise files here: Drive Link

Preparing Folders and Files :file_folder: (5 minutes)

Follow these steps to set up your workspace:

1. Download the C13_OpenCV_template folder from Google Drive
2. Save it into your Program G folder
3. Extract the folder contents
4. Open the extracted folder in VSCode

:bulb: Make sure to extract the folder completely before opening in VSCode to avoid any file access issues.

Read, Think, Code :computer:

Question One: Setup for NumPy and OpenCV (10 minutes)

1. Open the terminal in VSCode (Press `Ctrl + ``)
2. Install the required libraries: CODE_BLOCK_0
3. Open the
   file
4. Import both NumPy and OpenCV: CODE_BLOCK_1
5. Check and print the versions using: CODE_BLOCK_2 tip The version numbers might vary depending on when you install. As long as the installation succeeds, you're good to go!

Question 2: Read and show an image (15 minutes)

In the

file, complete these steps:

1. Import the required libraries: CODE_BLOCK_3

2. Read the image file "outing.jpg": CODE_BLOCK_4

3. Display the image in a window named "Outing": CODE_BLOCK_5

4. Keep the window open until a key is pressed: CODE_BLOCK_6

Expected Output:

:bulb: If the image doesn't appear, check that 'outing.jpg' is in the same folder as your Python file.

Question 3: Capture and show a video (20 minutes)

In the

file, create a video player:

1. Import the required libraries

2. Create a video capture object: CODE_BLOCK_7

3. Set up a while loop to read frames: CODE_BLOCK_8

4. Clean up resources: CODE_BLOCK_9 tip Common Issues

• Video won't play: Check that 'video.mp4' is in the correct folder
• Video plays too fast/slow: Adjust the waitKey() value (25ms is standard)
• Can't quit: Make sure you're pressing lowercase 'q'

Question 4: Capture and show webcam (15 minutes)

In the

file:

1. Copy your code from

2. Modify the video capture line to use your webcam: CODE_BLOCK_10

3. Optional: Add a message when webcam starts: CODE_BLOCK_11

:warning: Privacy Notice Your webcam will turn on when you run this code. Make sure you're in a comfortable environment before testing.

:bulb: Webcam Troubleshooting

• No webcam found: Try cv2.VideoCapture(1) or cv2.VideoCapture(2)
• Permission denied: Check your system's camera permissions for VSCode/Terminal
• Webcam LED stays on: Make sure to properly close the program with 'q'

Exercise Submission :emoji:

:warning: Important Submission Instructions Before submitting:

1. Test all your Python files (setup.py, image.py, video.py, webcam.py)
2. Make sure each file runs without errors
3. Take screenshots of your output if required
4. Zip your entire project folder

Submit your work here: Exercise Submission Form

Troubleshooting Guide :hammer_and_wrench:

Installation Issues:

• If pip install fails, try: python -m pip install --upgrade pip
• On Mac/Linux, you might need: pip3 install numpy opencv-python

Common Errors:

• ModuleNotFoundError: Library not installed correctly - reinstall using pip
• FileNotFoundError: Check file names and paths are correct
• (-215:Assertion failed): Usually means the image/video file wasn't found

Need Help? Ask your instructor or post in the class forum with your error message!