结合注意力模型与双峰高斯分布的深度哈希检索算法
Deep Hashing Retrieval Algorithm Combing Attention Model and Bimodal Gaussian Distribution
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摘要: 哈希检索因为具有存储空间小、检索速度快的特点而受到广泛关注.目前深度哈希算法存在2个主要问题:深度哈希编码本质上是二值化特征,并且编码长度较短,存在特征表达能力有限的问题;已有的深度哈希算法无法直接通过反向传播学习离散哈希编码,通常将离散值松弛为连续值来优化学习,存在量化误差的问题.针对以上问题,提出一种结合注意力模型和双峰高斯分布的深度哈希检索算法.该算法设计嵌入空间和通道注意力模型的网络结构,关注重要特征并抑制不必要特征,增强了哈希编码的特征表达能力;同时为了解决量化误差问题,将均值为+1/-1的双峰高斯分布作为先验分布,并借鉴变分自编码机的思想,提出通过KL散度约束哈希编码分布服从先验分布,以减少量化误差.在3个基准数据集CIFAR-10,ImageNet,NUS-WIDE上,在不同码位下计算MAP结果显示,其MAP值优于对比的其他算法,取得了良好的检索效果,验证了文中算法的有效性.Abstract: Hash retrieval has attracted wide attention because of its small storage space and fast retrieval speed. There are two problems in deep hashing methods: Deep hash codes are essentially binary features, and the coding length is short, so their feature representation abilities are limited;In addition, existing deep hashing algorithms cannot directly learn discrete hash codes by backpropagation, and usually relax discrete values to continuous values in their optimization procedure, so this leads to quantization errors. Aiming at above problems, we propose a deep hashing retrieval algorithm combining attention model and bimodal Gaussian distribution. The network structure with spatial and channel attention model, focusing on important features and suppressing unnecessary features, enhances the feature representation abilities of hash codes;To solve the quantization error problem, the bimodal Gaussian distribution with the mean of either +1 or-1 is used as the prior distribution. We refer to the idea of variational auto-encoder, and propose to constrain the hash codes distribution to obey the prior distribution with KL divergence. The mean average precision of our method on three benchmark databases CIFAR-10, ImageNet-100 and NUS-WIDE is better than other methods of comparison, which verifies the effectiveness of the algorithm in this paper.