A Linear Approximate Algorithm for Earth Mover's Distance with Thresholded Ground Distance

Effective and efficient image comparison plays a vital role in content-based image retrieval (CBIR). The earth mover’s distance (EMD) is an enticing measure for image comparison, offering intuitive geometric interpretation and modelling the human perceptions of similarity. Unfortunately, computing EMD, using the simplex method, has cubic complexity. FastEMD, based on min-cost flow, reduces the complexity to (O(N2log⁡N)). Although both methods can obtain the optimal result, the high complexity prevents the application of EMD on large-scale image datasets. Thresholding the ground distance can make EMD faster and more robust, since it can decrease the impact of noise and reduce the range of transportation. In this paper, we present a new image distance metric, EMD+, which applies a threshold to the ground distance. To compute EMD+, the FastEMD approach can be employed. We also propose a novel linear approximation algorithm. Our algorithm achieves ON complexity with the benefit of qualified bins. Experimental results show that (1) our method is 2 to 3 orders of magnitude faster than EMD (computed by FastEMD) and 2 orders of magnitude faster than FastEMD and (2) the precision of our approximation algorithm is no less than the precision of FastEMD

Characterization of the complete chloroplast genome of Pyrus pyrifolia ‘Yunhongli No. 1’

‘Yunhongli No. 1’ is a rare and well-colored red pear (Pyrus pyrifolia) germplasm resource, and is popular in the market due to its bright red color and high quality. This study used Illumina high-throughput sequencing technologies for red pear ‘Yunhongli No. 1’ of chloroplast genome sequencing and analysis. The genome features of P. pyrifolia ‘Yunhongli No. 1’ and the phylogenetic relationships were reported and established. The complete chloroplast genome is 160,113 bp in length, consisting of a pair of inverse duplication regions 26,386 bp, a large single-copy region 88,052 bp, and a small single-copy region 19,214 bp. The entire genome contains 80 messenger RNA (mRNA) genes, 30 transfer RNA (tRNA) genes, and 4 ribosomal RNA (rRNA) genes. The phylogenetic tree of 15 Rosaceae species revealed red pear ‘Yunhongli No. 1’ is more closely related to Pyrus communis × P. pyrifolia ‘Greensis.