PQ-WGLOH: A bit-rate scalable local feature descriptor
In this paper, we propose a compact yet discriminative local descriptor which tackles the wireless query transmission latency in mobile visual search. The descriptor captures gradient statistics of canonical patches over a log-polar location grid whose parameters are optimized using training samples. We quantize the resulting descriptor using product quantization. The descriptor achieves about 95% bits reduction compared with 128-Byte SIFT and allows adaptation of descriptor lengths to support user required performance. Moreover, accurate matching of descriptors with low complexity is allowed within several table lookup operations. We perform a comprehensive comparison with SIFT, GLOH and CHoG in the context of image retrieval, image matching and object localization. We achieve competing matching and retrieval performance with SIFT, GLOH with much fewer bits. In particular, the descriptor outperforms CHoG at the same bits on eight data sets contributed to MPEG Compact Descriptor for Visual Search(CDVS) Standardization.