Remote Interactive Browsing of Video Surveillance Content Based on JPEG 2000

摘要

In video surveillance applications, pre-stored images are likely to be accessed remotely and interactively upon user request. In such a context, the JPEG 2000 still image compression format is attractive because it supports flexible and progressive access to each individual image of the pre-stored content, in terms of spatial location, quality level, as well as resolution. However, when the client wants to play consecutive frames of the video sequence, the purely INTRA nature of JPEG 2000 dramatically penalizes the transmission efficiency. To mitigate this drawback, conditional replenishment mechanisms are envisioned. They convey arbitrary spatio-temporal segments of the initial video sequence directly through sporadic and rate-distortion (RD) optimized refresh of JPEG 2000 packets. Hence, they preserve JPEG 2000 compliance, while saving transmission resources. The replenishment algorithms proposed in this paper are original in two main aspects. First, they exploit the specificities of the JPEG 2000 codestream structure to balance the accuracy (in terms of bit-planes) of the replenishment across image subbands in a (RD)-optimal way. Second, they take into account the still background nature of video surveillance content by maintaining two reference images at the receiver. One reference is the last reconstructed frame, as proposed in the original replenishment framework. The other is a dynamically computed estimate of the scene background, which helps to recover the background after a moving object has left the scene. As an additional contribution, we demonstrate that the embedded nature of the JPEG 2000 codestream easily supports prioritization of semantically relevant regions of interest while browsing video content. An interesting aspect of this JPEG 2000-based prioritization is that it can be regulated a posteriori, after the codestream generation, based on the interest expressed by the user at browsing time. Simu-nlation results demonstrate the efficiency and flexibility of the approach compared to INTER-based solutions.