Definition
Bounding boxes are rectangular regions defined by coordinates (x, y, width, height) that mark the position and size of detected objects in images and video frames. In visual data processing - including anonymization - bounding boxes delineate the areas of interest such as faces, bodies, license plates or other identifying elements.
They are typically generated by object detection models and serve as input for further processing like blurring, masking or redaction.
Role in anonymization
Bounding boxes are essential for automatic and precise object selection in anonymization workflows. Their functions include:
- Defining exact areas to modify (e.g., blur, mask).
- Improving processing efficiency by limiting transformation scope.
- Enabling quantitative evaluation against ground truth data.
In AI systems, bounding boxes are generated per video frame and used to drive real-time anonymization operations.
AI-based implementation
Component | Description | Example technologies |
Object detectors | Models localizing objects in images | YOLOv5/YOLOv8, SSD, Faster R-CNN |
Output data format | List of boxes with labels and coordinates | COCO JSON, Pascal VOC XML |
Coordinates | x, y, width, height or x_min, y_min, x_max, y_max | Format varies by toolkit |
Frame-wise generation | Box generated for every frame (≥ 25 fps) | Requires low latency |
Confidence score | Detection certainty value (0-1) | Used for filtering weak detections |
Practical applications
- Urban surveillance - face blurring of pedestrians in public spaces.
- Dashcams - anonymizing license plates in road footage.
- Drones - hiding persons and vehicles in aerial footage.
- Telemedicine - masking patients in medical training videos.
- CMS/DAM systems - locating and marking personal data in large visual archives.
Challenges and limitations
Challenge | Description |
Occlusion and partial views | Hard to locate objects with incomplete visibility |
Object scaling | Object size varies with distance, affecting box accuracy |
Overlapping objects | Colliding boxes in crowded or fast-moving scenes |
Detection precision | Inaccurate boxes may expose or over-mask key elements |
Anonymization sync | Delay between detection and masking may cause drift |
Technical and normative references
- COCO Dataset Format - Microsoft, bounding box structure: cocodataset.org
- Pascal VOC XML - commonly used object annotation format.
- ISO/IEC 24029-1:2021 - AI robustness and object localization performance.
- YOLOv8 Documentation - Ultralytics, 2023, widely used open-source object detection toolkit.