331 research outputs found
Instance-weighted Central Similarity for Multi-label Image Retrieval
Deep hashing has been widely applied to large-scale image retrieval by
encoding high-dimensional data points into binary codes for efficient
retrieval. Compared with pairwise/triplet similarity based hash learning,
central similarity based hashing can more efficiently capture the global data
distribution. For multi-label image retrieval, however, previous methods only
use multiple hash centers with equal weights to generate one centroid as the
learning target, which ignores the relationship between the weights of hash
centers and the proportion of instance regions in the image. To address the
above issue, we propose a two-step alternative optimization approach,
Instance-weighted Central Similarity (ICS), to automatically learn the center
weight corresponding to a hash code. Firstly, we apply the maximum entropy
regularizer to prevent one hash center from dominating the loss function, and
compute the center weights via projection gradient descent. Secondly, we update
neural network parameters by standard back-propagation with fixed center
weights. More importantly, the learned center weights can well reflect the
proportion of foreground instances in the image. Our method achieves the
state-of-the-art performance on the image retrieval benchmarks, and especially
improves the mAP by 1.6%-6.4% on the MS COCO dataset.Comment: 10 pages, 6 figure
Hashing for Similarity Search: A Survey
Similarity search (nearest neighbor search) is a problem of pursuing the data
items whose distances to a query item are the smallest from a large database.
Various methods have been developed to address this problem, and recently a lot
of efforts have been devoted to approximate search. In this paper, we present a
survey on one of the main solutions, hashing, which has been widely studied
since the pioneering work locality sensitive hashing. We divide the hashing
algorithms two main categories: locality sensitive hashing, which designs hash
functions without exploring the data distribution and learning to hash, which
learns hash functions according the data distribution, and review them from
various aspects, including hash function design and distance measure and search
scheme in the hash coding space
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