A console/terminal demo of the OpenCV Canny edge detector, supporting Windows 11 and Ubuntu Linux 24.04. The input is smoothed with a Gaussian blur to suppress noise, converted to grayscale, and run through cv2.Canny. Canny uses two thresholds: gradients above the high threshold are edges, those below the low threshold are discarded, and the ones in between are kept only when they connect to a confirmed edge. Three example images ship under data/ (Lena, SC-150 and sample), and the results are saved to model/canny/. No GPU is involved.
[Folder Structure]
- CLAUDE.md / AGENT.md: program specification (identical content).
- CHANGELOG.md: change log.
- copyright.txt: copyright notice.
- data/: the example images Lena.png, SC-150.png and sample.png.
- model/canny/: the results gray.png (the blurred grayscale image) and canny.png (the edge map); the Lena examples are included.
- tool/tools.py: shared helpers.
- src/: the demo, the launcher scripts and this document.
- venv/: Python virtual environment, created by step 01.
[Prerequisites]
- Operating system: Windows 11 or Ubuntu Linux 24.04.
- Python 3 and pip.
- No GPU required; an ordinary CPU is enough.
[Instructions]
Step 1: Create the virtual environment
Delete the old venv/, create a fresh one and install the packages listed in src/requirements.txt. The script aborts loudly if pip fails.
Windows: src\01_venv_create.bat
Linux: bash src/01_venv_create.sh
Step 2: Activate the virtual environment
Activate the venv. On Linux, source the script.
Windows: src\02_venv_activate.bat
Linux: source src/02_venv_activate.sh
Step 3: Run the edge-detection demo
Run the Canny edge-detection demo. Any extra arguments are forwarded to the program.
Windows: src\03_canny.bat
Linux: bash src/03_canny.sh
To use your own image and thresholds, for example:
bash src/03_canny.sh --source data/SC-150.png --low 50 --high 150
Step 4: Remove the virtual environment
Delete the venv/ folder.
Windows: src\99_venv_clear.bat
Linux: bash src/99_venv_clear.sh
[Python Entry Point]
- src/canny.py: [--source IMG] [--blur-kernel 7] [--low 10] [--high 100] [--output-dir DIR] [--show]. The defaults are data/Lena.png, a 7×7 Gaussian blur and Canny thresholds of 10 and 100. It saves gray.png (the blurred grayscale image) and canny.png (the edge map) to model/canny/; --show also opens the results in windows. --blur-kernel must be odd.
[References]
- OpenCV Canny edge detection tutorial: https://docs.opencv.org/4.x/da/d22/tutorial_py_canny.html
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