Privacy-Preserving Action Recognition using Coded Aperture Videos
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The risk of unauthorized remote access of streaming video from networked cameras underlines the need for stronger privacy safeguards. Towards this end, we simulate a lens-free coded aperture (CA) camera as an appearance encoder, i.e., the first layer of privacy protection. Our goal is human action recognition from coded aperture videos for which the coded aperture mask is unknown and does not require reconstruction. We insert a second layer of privacy protection by using non-invertible motion features based on phase correlation and log-polar transformation. Phase correlation encodes translation while the log polar transformation encodes in-plane rotation and scaling. We show the key property of the translation features being mask-invariant. This property allows us to simplify the training of classifiers by removing reliance on a specific mask design. Results based on a subset of the UCF and NTU datasets show the feasibility of our system.
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