基于压缩域的图象检索技术研究进展

压缩标准的出现 ,使得图象数据格式普遍为压缩格式 ,从而促进了压缩域内图象检索技术的迅速发展 .为了使人们对基于压缩域的图象检索技术有一概括了解 ,该文对目前的压缩域检索技术进行了回顾和讨论 :首先 ,介绍了图象检索系统的基本概念 ;然后 ,分类分析了不同压缩域的检索技术 ,包括变换域方法 (如傅立叶变换、离散余弦变换 (DCT)以及子带和小波变换 )和空域方法 (如矢量量化和分形等 ) ;接着 ,对这些检索方法进行了讨论和比较 ,并得出一些有用的结论 ;还举例介绍了基于压缩域图象检索技术的实际应用 ;最后对压缩域图象检索技术的研究发展及其应用前景指出了一些可能的方向 .     

图象检索算子开放测试平台T-Brief设计与实现

基于内容的图象检索是近年来多媒体技术领域发展的一个热点之一,大量基于特征的检索算法不断涌现。该文介绍一个对算法开放的抽取特征检索图象的算法测试平台,该平台可以即时集成现有的多种不同算法,并便于管理,同时它还提供了诸如综合检索,渐进检索等功能,可用于算法研究,性能比较等。     

基于整体区域相似的互动式图象检索模型

高效的基于内容的图象检索在许多领域得到了广泛的应用 ,基于内容的图象检索研究领域已经建立了一些系统 ,但在实际使用中 ,这些系统均有如下欠缺 :(1)这些系统均期望以相同的方法来处理各种不同类型的图象检索 ;(2 )这些系统在设计时 ,均缺乏从使用者的需求出发 .实际上 ,由于不同的检索方式是针对不同类型的图象 ,为此 ,提出了一个基于整体区域相似匹配的图象互动式检索系统 ,该系统是一个基于小波变换的特征提取和图象整体区域相似的、语义分类和互动方法的图象检索系统 .与其他检索方法相比较 ,此方法允许自适应查找和互动 ,因此可缩小查找范围 ,以提高检索效率 .实验结果表明 ,该系统比其他一些系统精确和高效     

基于小波模糊聚类的均质纹理和非均质纹理图象检索

基于内容的图象检索是近年来的研究热点 ,为此提出了一种自动区分均质纹理和非均质纹理图象 ,并对这两类图象分别进行检索的算法 .算法首先从图象离散小波变换的低频子带提取一定的颜色和纹理特征用于模糊聚类 ,将图象的低频子带分割为一定的区域 ;然后根据分割的结果将图象自动语义分类为均质纹理或者非均质纹理图象 ;最后对均质纹理和非均质纹理图象分别提取不同的特征矢量 ,并按照一定的相似度准则检索图象 .实验结果表明 ,该算法具有良好的均质纹理和非均质纹理图象分类和检索性能 .     

基于内容的图象检索技术的研究和发展

多媒体技术和数字图书馆的发展和应用,使基于图象内容的检索技术,成为图象处理和计算机视觉的前沿问题。图象数据库检索查询的研究目的就是实现自动地、智能化地检索和管理图象。文章详细介绍了该技术的研究状况和具体应用,并探讨了其发展前景。     

基于独立关键子块和三角树的快速图象检索新方法

由于图象存储数据量非常大,因此提取图象特征和检索极为耗时.为了提高图象检索效率,将文本检索中的有效检索方法(基于关键字频率与关键字逆文档频率乘积的索引模型)结合三角树索引机制应用到基于内容的图象检索,提出了一种基于独立关键子块和三角树的快速图象检索新方法.该方法首先用独立分量分析将样本图象子块中的直方图特征映射到色彩概念空间来得到类似于文本中关键字的独立关键子块;然后再用训练好的模糊支持向量机去识别每幅图象中所包含的独立关键子块,由于独立分量分析能够使特征彼此保持高阶独立性,因此该方法与主成分分析方法对比,具有较高检索效率;最后,再通过构造三角树来来为图象数据库建立分层索引结构,以加快检索速度.     

Web上基于内容的图象检索技术

Web上基于内容的图象检索集基于内容的图象检索和Internet网络这两项技术于一体,它对图象媒体的广泛应用具有一定的实用价值,同时对图象处理技术如何适应网络要求又有一定的理论研究价值,本文研究了特征提取、分布运算、网络实现等Web上基于内容的图象检索的相关技术,建立了一个单机上的图象检索系统并用该系统检验了自己提出的图象检索方法.另外在Web上实现了使用该方法的图象检索,实践证明小波形状不变矩对图象的形状匹配具有较好的效果.     

基于内容的视频查询系统研究

由于多媒体数据库管理和检索的效率直接决定了人们利用多媒体数据信息的效率,因此随着MPEG-7标准的提出,基于内容的图象/视频存储和检索已成为研究的热点.为了快速地对视频进行浏览和检索,在研究基于内容的视频数据库管理和检索等热点问题的基础上,首先使用MPEG-7视觉内容描述子和语义描述子来构建视频数据库的语义结构,并结合底层视觉特征和高层语义特征,采用相关反馈机制和半自动权重更新体制来对视频数据库进行管理和检索;然后采用语法分析器来支持自然语言查询;最后在此基础上实现了基于内容的视频数据库的管理和查询系统.实验证明,该系统能够有效地对视频数据进行管理和检索,并且具有一定的智能性和适应性.     

基于内容的图像检索介绍

基于内容特征的图象检索(CBIR)是目前国内外研究的一个热点。本文简要介绍了基于内容的图像检索技术的发展过程及主要原理,重点论述了基于内容的图像检索常用关键技术——图像视觉特征的描述和提取。     

基于内容的图像检索介绍

基于内容特征的图象检索（CBIR）是目前国内外研究的一个热点。本文简要介绍了基于内容的图像检索技术的发展过程及主要原理，重点论述了基于内容的图像检索常用关键技术——图像视觉特征的描述和提取。     

Relevance Feedback and Learning in Content-Based Image Search

A major bottleneck in content-based image retrieval (CBIR) systems or search engines is the large gap between low-level image features used to index images and high-level semantic contents of images. One solution to this bottleneck is to apply relevance feedback to refine the query or similarity measures in image search process. In this paper, we first address the key issues involved in relevance feedback of CBIR systems and present a brief overview of a set of commonly used relevance feedback algorithms. Almost all of the previously proposed methods fall well into such framework. We present a framework of relevance feedback and semantic learning in CBIR. In this framework, low-level features and keyword annotations are integrated in image retrieval and in feedback processes to improve the retrieval performance. We have also extended framework to a content-based web image search engine in which hosting web pages are used to collect relevant annotations for images and users' feedback logs are used to refine annotations. A prototype system has developed to evaluate our proposed schemes, and our experimental results indicated that our approach outperforms traditional CBIR system and relevance feedback approaches.     

一种基于记忆的图像检索相关反馈策略

相关反馈在基于内容的图像检索中成为提升检索效率的一项重要技术。然而,在图像检索中,高层语义与底层特征之间存在着巨大的"语义鸿沟",传统的相关反馈技术需要多次反馈才能获得满意结果,这使得用户的检索任务既耗时且繁琐。因此,本文通过对图像检索反馈日志信息的存储及使用过程进行分析,提出一种新的基于记忆的相关反馈策略。通过原型系统实验,与传统反馈策略相比,本文提出的策略对检索效率有明显改善。     

Neighborhood preserving regression for image retrieval

In content-based image retrieval (CBIR), relevance feedback has been proven to be a powerful tool for bridging the gap between low level visual features and high level semantic concepts. Traditionally, relevance feedback driven CBIR is often considered as a supervised learning problem where the user provided feedbacks are used to learn a distance metric or classification function. However, CBIR is intrinsically a semi-supervised learning problem in which the testing samples (images in the database) are present during the learning process. Moreover, when there are no sufficient feedbacks, these methods may suffer from the overfitting problem. In this paper, we propose a novel neighborhood preserving regression algorithm which makes efficient use of both labeled and unlabeled images. By using the unlabeled images, the geometrical structure of the image space can be incorporated into the learning system through a regularizer. Specifically, from all the functions which minimize the empirical loss on the labeled images, we select the one which best preserves the local neighborhood structure of the image space. In this way, our method can obtain a regression function which respects both semantic and geometrical structures of the image database. We present experimental evidence suggesting that our algorithm is able to use unlabeled data effectively for image retrieval.     

Image retrieval using nonlinear manifold embedding

The huge number of images on the Web gives rise to the content-based image retrieval (CBIR) as the text-based search techniques cannot cater to the needs of precisely retrieving Web images. However, CBIR comes with a fundamental flaw: the semantic gap between high-level semantic concepts and low-level visual features. Consequently, relevance feedback is introduced into CBIR to learn the subjective needs of users. However, in practical applications the limited number of user feedbacks is usually overwhelmed by the large number of dimensionalities of the visual feature space. To address this issue, a novel semi-supervised learning method for dimensionality reduction, namely kernel maximum margin projection (KMMP) is proposed in this paper based on our previous work of maximum margin projection (MMP). Unlike traditional dimensionality reduction algorithms such as principal component analysis (PCA) and linear discriminant analysis (LDA), which only see the global Euclidean structure, KMMP is designed for discovering the local manifold structure. After projecting the images into a lower dimensional subspace, KMMP significantly improves the performance of image retrieval. The experimental results on Corel image database demonstrate the effectiveness of our proposed nonlinear algorithm.     

一种具有相关反馈的图像检索方法

图像底层特征和高层语义之间存在着巨大的语义鸿沟.受限于图像理解技术的发展水平和对认知的理解水平.目前,对图像语义的描述还无法由计算机自动建立.要克服语义鸿沟,需引入相关反馈机制.特征提取采用结合空间信息的颜色一致直方图方法,并建立了基于方差分析的权值调整方法进行反馈调节,有效地提高了图像检索准确率.     

Joint semantics and feature based image retrieval using relevance feedback

Relevance feedback is a powerful technique for image retrieval and has been an active research direction for the past few years. Various ad hoc parameter estimation techniques have been proposed for relevance feedback. In addition, methods that perform optimization on multilevel image content model have been formulated. However, these methods only perform relevance feedback on low-level image features and fail to address the images' semantic content. In this paper, we propose a relevance feedback framework to take advantage of the semantic contents of images in addition to low-level features. By forming a semantic network on top of the keyword association on the images, we are able to accurately deduce and utilize the images' semantic contents for retrieval purposes. We also propose a ranking measure that is suitable for our framework. The accuracy and effectiveness of our method is demonstrated with experimental results on real-world image collections.     

发掘相关反馈日志中关联信息的图像检索方法

相关反馈日志蕴含着丰富的对象语义关联信息,但大多数基于内容的图像检索(CBIR)方法却缺乏对它们的重用.提出一种发掘反馈日志中图像关联信息的自动化图像检索方法,将反馈事例中图像的共生现象视为一定上下文中的图像分类.检索时,结合CBIR的检索结果和多种上下文中的图像分类实例,借鉴HITS算法的思想从中提炼图像的本质性关联,获得综合内容和语义的图像检索结果.对6万幅Corel图像数据库的实验表明,该方法可以显著改善查全率和查准率,且检索结果能够更好地满足用户的语义检索需求.     

A scalable approach for content based image retrieval in cloud datacenter

The emergence of cloud datacenters enhances the capability of online data storage. Since massive data is stored in datacenters, it is necessary to effectively locate and access interest data in such a distributed system. However, traditional search techniques only allow users to search images over exact-match keywords through a centralized index. These techniques cannot satisfy the requirements of content based image retrieval (CBIR). In this paper, we propose a scalable image retrieval framework which can efficiently support content similarity search and semantic search in the distributed environment. Its key idea is to integrate image feature vectors into distributed hash tables (DHTs) by exploiting the property of locality sensitive hashing (LSH). Thus, images with similar content are most likely gathered into the same node without the knowledge of any global information. For searching semantically close images, the relevance feedback is adopted in our system to overcome the gap between low-level features and high-level features. We show that our approach yields high recall rate with good load balance and only requires a few number of hops.     

Collaborative image retrieval via regularized metric learning

In content-based image retrieval (CBIR), relevant images are identified based on their similarities to query images. Most CBIR algorithms are hindered by the semantic gap between the low-level image features used for computing image similarity and the high-level semantic concepts conveyed in images. One way to reduce the semantic gap is to utilize the log data of users' feedback that has been collected by CBIR systems in history, which is also called “collaborative image retrieval.” In this paper, we present a novel metric learning approach, named “regularized metric learning,” for collaborative image retrieval, which learns a distance metric by exploring the correlation between low-level image features and the log data of users' relevance judgments. Compared to the previous research, a regularization mechanism is used in our algorithm to effectively prevent overfitting. Meanwhile, we formulate the proposed learning algorithm into a semidefinite programming problem, which can be solved very efficiently by existing software packages and is scalable to the size of log data. An extensive set of experiments has been conducted to show that the new algorithm can substantially improve the retrieval accuracy of a baseline CBIR system using Euclidean distance metric, even with a modest amount of log data. The experiment also indicates that the new algorithm is more effective and more efficient than two alternative algorithms, which exploit log data for image retrieval.