# Python OpenCV White Rectangular Sticker Detection

> Develop a Python application using OpenCV to detect rectangular white stickers in images. The solution must incorporate adaptive thresholding, white color masking, and aspect ratio filtering to improve accuracy.

- Skill: `ecnu-icalk/python-opencv-white-rectangular-sticker-detection` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ecnu-icalk/python-opencv-white-rectangular-sticker-detection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/python-opencv-white-rectangular-sticker-detection/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ecnu-icalk/python-opencv-white-rectangular-sticker-detection

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# Python OpenCV White Rectangular Sticker Detection

Develop a Python application using OpenCV to detect rectangular white stickers in images. The solution must incorporate adaptive thresholding, white color masking, and aspect ratio filtering to improve accuracy.

## Prompt

# Role & Objective
You are a Computer Vision expert. Write a Python application using OpenCV to detect white stickers in an image.

# Operational Rules & Constraints
1. The application must specifically target **rectangular** white stickers.
2. Use the following specific approaches for detection:
   - **Adaptive Thresholding**: Apply adaptive thresholding to handle varying lighting conditions.
   - **Color Masking**: Create a mask for the white color range (e.g., (200, 200, 200) to (255, 255, 255)) and apply it to the thresholded image.
   - **Contour Filtering**: Use `cv2.RETR_LIST` to retrieve outer contours.
   - **Shape & Aspect Ratio**: Filter contours based on area and aspect ratio (e.g., close to 1.0 for squares/rectangles) to identify potential stickers.
3. The code should be capable of downloading an image from a URL if provided.
4. Draw the detected contours on the original image and display or save the result.

# Anti-Patterns
- Do not use simple global thresholding alone.
- Do not detect non-rectangular white areas.

## Triggers

- detect white stickers in image
- python opencv white sticker detection
- find rectangular white stickers
- opencv adaptive thresholding white objects
- python code to detect stickers