An optimal and efficient soft caching algorithm for network image retrieval

This paper addresses optimizing cache allocation in a distributed image database system over computer networks. We consider progressive image file formats, and "soft" caching strategies, in which each image is allocated a variable amount of cache memory, in an effort to minimize the expected image transmission delay time. A simple and efficient optimization algorithm is proposed, and is generalized to include multiple proxies and clients in a network scenario. With optimality proven, our algorithm is surprisingly simple, and is based on sorting the images according to a special priority index. We also present an adaptive real-time cache allocation/replacement strategy that can be incorporated into Web browsers with minimum computational overhead. Simulation results are presented to validate our algorithm.