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