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Learning-Based Local Visual Representation and Indexing by Qionghai Dai, Hongxun Yao, Ling-Yu Duan, Yue Gao, Rongrong Ji

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Chapter 3

Unsupervised Dictionary Optimization

Abstract

The core part of the learning-based local representation lies in the visual dictionary and its indexing structure, e.g., how to optimize the local feature-space quantization scheme. In Chapter 2, the design of the optimal interest-point detector was covered, while in this chapter, we introduce and discuss the way to optimize the dictionary construction-based on hierarchical metric learning unsupervised. We will show that the traditional Euclidean distance-based metric is unsuitable for k-means clustering, which would push clusterings located at dense regions and hence result in a biased distance metric. To deal with this issue, this chapter introduces density-based metric learning (DML) ...

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