SORTING LOCAL DESCRIPTORS FOR LOW BIT RATE MOBILE VISUAL SEARCH

State-of-the-art mobile visual search systems put emphasis on developing compact visual descriptors [4][6], which enables low bit rate wireless transmission instead of delivering an en-tire query image. In this paper, we address the orderless na-ture of the transmission set of query descriptors. We propose to adapt the orders of local descriptors in transmission, which subsequently yields more consistent statistic distributions in each feature dimension towards more efficient residual coding based compression. Our scheme further enables lossy sorting by an adaptive quantization strategy within each feature di-mension, which largely improves the compression rates of the residual coding in each dimension. We show that the perfor-mance degeneration of such lossy sorting is acceptable in our mobile landmark search applications. Our approach’s effec-tiveness and efficiency is demonstrated via extensive experi-mental comparisons to state-of-the art works in both mobile visual descriptors [2][4] and compact image signatures [5]. Index Terms — mobile visual search, compressive visual descriptors, sorting, lossy compression 1