MediaEval 2013 Visual Privacy Task: Warping-based Privacy Protection Tool

In this paper, we describe EPFL privacy protection tool submitted to the MediaEval 2013 Visual Privacy task. The goal of the task is to obscure faces and other personal items of people in the provided surveillance clips to preserve their personal privacy. In the privacy protection tool, we used a combination of reversible privacy protection filter based on geometric warping transformation, randomized saturation filter, masking with partial opacity, and pixelization. The aim of the implementation was to achieve an acceptable balance between privacy and intelligibility, as well as, privacy and appropriateness. The results of both objective and subjective evaluations provided by the organizers of the task demonstrated that our privacy protection tool leads to high appropriateness and intelligibility (the surveillance task can be performed with high accuracy) while keeping strong privacy protection.