Direct content access and extraction from JPEG compressed images

摘要

In this paper, we propose a novel design of content access and extraction algorithm for compressed image browsing and indexing, which is critical for all visual information systems. By analyzing the relationship between DCT coefficients of one block of 8×8 pixels and its four sub-blocks of 4×4 pixels, the proposed algorithm extract an approximated image with smaller size for indexing and content browsing without incurring full decompression. While the computing cost is significantly lower than full decompression, the approximated image also reserves the content features, which are sufficient for indexing and browsing as evidenced by our extensive experiments.