Reduction of waiting time for retrieving images from distributed image databases

This paper describes the reduction of the waiting time for users in high performance image retrieval systems on multimedia networks. Both the processing times for the systems and waiting times for the users were measured in the image retrieval systems. The processing time was found to be reduced to one-half of that in the conventional system when the image directories were installed in the new system. A mathematical model to derive the waiting time W from the processing time P was obtained as λ P²/(1-λ P), where λ is the rate of occurrence of the requests for the image retrieval. The calculated values were confirmed to agree with experimental data. Based on the studies, a high-speed image retrieval system was constructed using an image directory. When the processing time for the image retrieval decreased to one-half of that in the conventional system, the waiting time became approximately one eighth of the original value