Are Depth Field Cameras Preserving Anonymity?

This paper presents a preliminary study to assess the degree of anonymization provided by the use of depth field camera, for various degrees of pixelization. First the passage of 24 participants under a depth field camera was recorded. Each of the corresponding video was degraded with various levels of pixelization. Then the videos were shown to a subset of 6 participants, using a dedicated software which presents the videos in random order, starting with the lowest resolution. Each participant had to recognize themself, and in order to achieve this goal, could progressively improve the resolution. Our results question the fact that pixelization is the proper way to improve anonymity. Actually recognition seems to a large extend to be based on dynamic features rather than on the resolution of the picture. Besides we identify mostly 2 groups of responses: either the person can identify him/herself whatever the pixelization, or the recognition task is out of reach. Thus, the ability to use dynamic features could be person dependent. Further exploration would be useful to confirm this observation.