Ahstract-Privacy-protecting technology is essential in this surveillance society. The applications of cameras widely vary, e.g., crime surveillance, monitoring of an environment, and marketing.Furthermore, the scale of surveillance systems is predicted to become more diverse (from home area networks to wide area networks) due to the decrease in size and price of cameras.Therefore, a simple privacy protection system that does not require central servers or large databases is needed. Scrambling private information in a captured image can be a solution to sim plifying a system. We propose an image-scrambling method for bitmap and JPEG formatted images to private information. Our method enables access control by providing keys to authorized individuals. They cannot view private information that they do not have permission to access. The image's format is retained; therefore, no special viewer is necessary in display-only console. Experimental results suggest that scramble level can be controlled linearly by using parameters (three for JPEG formatted image, and one for bitmap image). We also developed a demo system for this method and confirm that this method can be applied to embedded systems such as those equipped with surveillance cameras.
SUMMARYThis paper is concerned with content-addressable memory (CAM), which is a kind of functional memory. Flexible multiport content-addressable memory (FMCAM) is proposed, in which flexible retrieval functions and a multiport structure are realized. The implementation and an evaluation are presented. It is known that CAM offers high speed of the matching retrieval function. On the other hand, there are problems in practice concerning the relation between the processing speed and the number of comparators, and also the problem of cost, which have prevented its widespread use. Consequently, we developed the following FMCAM. Multiport CAM is realized by reducing the increase of the number of comparators while retaining highspeed matching retrieval functions. Functions for flexible retrieval can be added by implementation in an FPGA. By the categorization process and the use of a ring counter, multiple processing operations can be performed immediately while reducing the number of comparators. This improves the performance of the CAM itself. Another advantage is that FMCAM alone can perform the same processing in situations in which parallel CAM should be applied. After implementing the proposed FMCAM, several tests were performed for comparison. Excellent values were obtained: the AT product was 37.5% lower on average than in conventional CAM, and the increase in hardware complexity was by a factor of 1.57 even if the number of ports was increased by a factor of 4.
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