Image Similarity Judgment Method for Waste Printed Circuit Boards
Hikaru Shirai1, Ryo Oishi2, Yoichi Kageyama1
1Department of Informatics and Data Science, Faculty of Informatics and Data Science, Akita University (Tegata Campus), 1-1 Tegata Gakuen-machi, Akita-shi 010-8502, Akita, Japan.
Sensors (Basel, Switzerland)
|February 27, 2026
Summary
Automated image analysis streamlines waste printed circuit board (WPCB) recycling. An algorithm accurately assesses WPCB similarity, improving efficiency and reducing manual inspection errors in metal recovery.
Area of Science:
- Materials Science
- Computer Science
- Environmental Engineering
Background:
- Waste printed circuit boards (WPCBs) contain valuable metals, necessitating efficient recovery methods.
- Current manual WPCB classification is labor-intensive, slow, and error-prone.
- Automated methods are needed to improve the efficiency and accuracy of WPCB recycling.
Purpose of the Study:
- To develop an image-based algorithm for automated waste printed circuit board similarity assessment.
- To enhance the accuracy and efficiency of WPCB classification for metal recovery.
- To reduce reliance on manual inspection in the WPCB recycling process.
Main Methods:
- Extraction of visual features from WPCB images, including hue, terminal region characteristics, structural complexity, and integrated circuits.
- Computation of similarity scores using weighted feature contributions.
- Development of classification strategies based on identified board-specific characteristics.
Main Results:
- The proposed image-based algorithm achieved 88.0% accuracy for targeted PCB types.
- The method demonstrated superior performance compared to a self-supervised contrastive learning approach.
- Key features like hue value and structural complexity were identified as highly effective for similarity evaluation.
Conclusions:
- An automated, image-driven WPCB similarity assessment algorithm can significantly improve recycling efficiency.
- The developed method offers a viable alternative to manual WPCB classification, reducing errors and operational costs.
- This approach facilitates streamlined metal recovery from WPCBs, contributing to sustainable resource management.


