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 n₁×n₂, the proposed algorithm takes O(n₁logT+P) time to perform the window query, where n₁=max(n₁, n₂) and T×T is the image size; P is the number of outputted codes. The proposed algorithm improves the naive algorithm, which needs O(n₁n₂log 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.