The Defence Science and Technology Laboratory wished to specify requirements for long range imaging systems that could be passed to system integrators. We were interested in facial identification and wanted a suitable metric. The UK Home Office produced a test to verify the setup of CCTV cameras based on facial identification. This used synthetic faces with a given number of pixels across the face. This is now part of British Standard EN 62676-4:2015. We were interested in how the number of pixels affected the probability of the faces being correctly identified. We ran an observer trial using the synthetic faces pixelated at different resolutions. It was found that the probability of correctly identifying the pixelated faces did not exceed ~60% however many pixels. This led to us suggesting that a pragmatic pixel count was at the 50% probability point (in-line with Johnson’s) of correctly identifying faces. We have christened this actionable surveillance identification (ASI).

Date Published: 13 May 2019
PDF: 17 pages
Proc. SPIE 10995, Pattern Recognition and Tracking XXX, 109950K (13 May 2019); doi: 10.1117/12.2518458

Published in SPIE Proceedings Vol. 10995:
Pattern Recognition and Tracking XXX
Mohammad S. Alam, Editor(s)