Space-filling approach for fast window query on compressed images

Based on the space-filling approach, this paper presents a fast algorithm for window query on compressed images. Given a query window of size n/sub 1//spl times/n/sub 2/, the proposed algorithm takes O(n/sub 1/logT+P) time to perform the window query, where n/sub 1/=max(n/sub 1/, n/sub 2/) and T/spl times/T is the image size; P is the number of outputted codes. The proposed algorithm improves the naive algorithm, which needs O(n/sub 1/n/sub 2/log T+P) time, significantly. Some experimentations are carried out to demonstrate the computational advantage of the proposed algorithm. From the experimental results, it is observed that the proposed algorithm has about 72-98% time improvement when compared to the naive algorithm.