This document provides an overview of a visual privacy task that aims to obscure or scramble regions of people in videos in an acceptable and attractive way while protecting their identity. The task involves 200 test videos ranging from 30-90 seconds long and uses an evaluation set of 12 videos to objectively and subjectively evaluate three approaches based on accuracy, anonymity, intelligibility, quality, and user study questionnaires. The results show that the University of Reading approach had the best performance based on the objective metrics and user study feedback.

1. Visual Privacy Task
Overview
Tomas Piatrik, Queen Mary University of London
Atta Badii, University of Reading

2. Task Description
• Visual privacy protection of people occurred in a
video taking into consideration the acceptability
and attractiveness of the resulting obscured or
scrambled region.

3. Data
200 videos
• 30s-90s
• 25fps, 30fps
• 640x480, 704x576
• Daytime
• Evening
• People wearing accessories (hat, scarf, sunglasses)
Evaluation Set – 12 videos (4 per each category)

4. Evaluation Methodology
1. Objective Evaluation
• Accuracy of the bounding boxes
• Anonymity – evaluated by automatic face
detection
• Intelligibility – evaluated by object tracking
• Quality: SSIM & PSNR – similarity between the
original and obscured images
2. User Study (subjective evaluation)
• 20 subjects
• 2-range score (0,1; 0-0,5-1)

5. User Study
Questionnaires
• General Evaluation
• Clip Evaluation - cropped obscured face
• Clip Evaluation – whole frames

6. User Study
Questionnaire:
• Is the person of interest wearing sunglasses? …
• What is the person’s gender?
• What is the person’s ethnicity?
• Is it possible to guess the person’s facial expression?
• Is the masking hiding sufficient features?
• Do you feel that this masking technique could protect
your identity if used on CCTV systems?
• Do you find the masking effect distracting?
• Do you find the masking effect irritating?
• …

7. Results – objective evaluation
Participants:
co-organising team
Objective evaluation:
Accuracy Anonymity Intelligibility SSIM PSNR
EPFL 0.24 1.00 0.85 0.92 28.26
Eurecom 0.37 1.00 0.82 0.93 32.89
UoR 0.50 1.00 0.93 0.96 35.80

8. Results – User Study

9. Results – User Study

10. Thank You