基于核密度估计的图像自动标注方法

提出一种基于概率模型的图像自动语义标注方法,将图片自动标注看作一个多类分类问题,通过无参数的核密度估计,实现用含有共同标注词的图片组估计视觉特征和相应标注词之间关系的机制。选取表达能力较好的基于CPAM的视觉特征,无须对图像进行语义分割处理,有效提高核密度估计的效率。在基准数据集上进行实验,结果表明,该模型能够获得比当前其他相关方法更好的标注性能。     

基于贝叶斯理论的图像标注和检索

图像自动语义标注是基于内容图像检索中很重要且很有挑战性的工作.提出用语义约束的聚类方法对分割后的图像区域进行聚类,在图像标注阶段,使用贪心选择连接(GSJ)算法找出聚类区域的独立子集,然后使用贝叶斯理论进行语义标注.对图像进行标注以后,使用标注的关键字进行检索.在一个包含500幅图像的图像库进行实验,结果表明,提出的方法具有较好的检索性能.     

一种新的图像语义自动标注与检索算法*

提出了一种新的利用图像语义词汇表进行图像自动标注与检索的方法.采用混合层次模型在已标注好的训练图像集上计算图像区域类与关键字的联合概率分布,并用生成的模型标注未曾观察过的测试图像集,或用来进行基于语义的图像检索.实验结果表明,该方法在标注、检索精度和效率方面均优于当前其他方法.     

基于t混合模型的自动图像标注

图像自动标注的实质是通过对图像视觉特征的分析来提取高层语义关键词用于表示图像的含义,从而使得现有图像检索问题转化为技术已经相当成熟的文本检索问题,在一定程度上解决了基于内容图像检索中存在的语义鸿沟问题.采用t混合模型在已标注好的训练图像集上计算图像区域类与关键字的联合概率分布,在此基础上,对未曾观察过的测试图像集,利用生成的模型根据贝叶斯最小错误概率准则实现自动图像标注.实验结果表明,该方法能有效改善标注结果.     

基于语义分类的文物图像标注研究

由于图像数据中普遍存在的“语义鸿沟”问题，传统的基于内容的图像检索技术对于数字图书馆中的图像检索往往力不从心。而图像标注能有效地弥补语义的缺失。文中分析了图像语义标注的现状以及存在的问题，提出了基于语义分类的文物语义标注方法。算法首先通过构建一个Bayes语义分类器对待标注图像进行语义分类，进而通过在语义类内部建立基于统计的标注模型，实现了图像的语义标注。在针对文物图像进行标注的实验中，该方法获得了较好的标注准确率和效率。     

基于视觉语义主题的图像自动标注

为减小图像检索中语义鸿沟的影响,提出了一种基于视觉语义主题的图像自动标注方法.首先,提取图像前景与背景区域,并分别进行预处理;然后,基于概率潜在语义分析与高斯混合模型建立图像底层特征、视觉语义主题与标注关键词间的联系,并基于该模型实现对图像的自动标注.采用corel 5数据库进行验证,实验结果证明了本文方法的有效性.     

基于本体的图像自动标注

提出一种新的图像本体标注的框架,结合领域本体中概念的关系,通过层次概率标注来获得图像高层语义概念的标注,实现待标注图像语义的自动标注。我们将图像的语义可以定义为属性概念和高层抽象概念,采用二次标注方法实现对于图像语义的自动标注。实验证明,本文的方法可以使图像获得丰富的高层抽象语义概念标注,从而缩小"语义鸿沟",有效提高了检索的效率和精确度。     

基于文本和内容的图像检索算法

为了提高图像检索的效率,提出一种基于文本和内容的图像检索算法。该算法采用稠密的尺度不变特征转换（ DSIFT）构造视觉单词的方式来描述图像内容,依据基于概率潜在语义分析（ PLSA）模型的图像自动标注方法获取的视觉语义对查询图像进行初步检索,在此结果集上对筛选出的语义相关图像按内容相似度排序输出。在数据集Corel1000上的实验结果表明,该算法能够实现有效的图像检索,检索效率优于单一的基于内容的图像检索算法。     

一种新的图像语义自动标注模型

根据图像低层特征和高级语义间的对应关系,自动进行图像语义标注是目前图像检索系统研究的热点。简要介绍了基于图像语义连接网络的图像检索框架,提出了一种基于该框架的图像自动标注模型。该模型通过积累用户反馈信息,学习并获得图像语义,从而进行自动的图像标注。图像语义及标注可以在与用户交互过程中得到实时更新。还提出了一种词义相关度分析的方法剔除冗余标注词,解决标注误传播的问题。通过在Corel图像集上的对比实验,验证了该方法的有效性。     

一种基于本体与描述文本的网络图像语义标注方法

网络图像语义自动标注是实现对互联网中海量图像管理和检索的有效途径,而自动有效地挖掘图像语义是实现自动语义标注的关键。网络图像的语义蕴含于图像自身,但更多的在于对图像语义起不同作用的各种描述文本,而且随着图像和描述知识的变化,描述文本所描述的图像语义也随之变化。提出了一种基于领域本体和不同描述文本语义权重的自适应学习的语义自动标注方法,该方法从图像的文本特征出发考查它们对图像语义的影响,先通过本体进行有效的语义快速发现与语义扩展,再利用一种加权回归模型对图像语义在其不同类型描述文本上的分布进行自适应的建模,进而实现对网络图像的语义标注。在真实的Wcb数据环境中进行的实验中,该方法的有效性得到了验证。     

Symbolic image indexing and retrieval by spatial similarity: An approach based on B-tree

In this paper, the problem of indexing symbolic images based on spatial similarity is addressed. A model based on modified triangular spatial relationship (TSR) and B-tree is proposed. The model preserves TSR among the components in a symbolic image by the use of quadruples. A Symbolic Image Database (SID) is created through the construction of B-tree, an efficient multilevel indexing structure. A methodology to retrieve similar symbolic images for a given query image is also presented. The presented retrieval model has logarithmic search time complexity. The study made in this work reveals that the model bears various advantages when compared to other existing models and it could be extended towards dynamic databases. An extensive experimentation is conducted on various symbolic images and also on the ORL and YALE face databases. The results of the experimentation conducted have revealed that the proposed scheme outperforms the existing algorithms and is of practical relevance.     

Space and time bounds on indexing 3D models from 2D images

Model-based visual recognition systems often match groups of image features to groups of model features to form initial hypotheses, which are then verified. In order to accelerate recognition considerably, the model groups can be arranged in an index space (hashed) offline such that feasible matches are found by indexing into this space. For the case of 2D images and 3D models consisting of point features, bounds on the space required for indexing and on the speedup that such indexing can achieve are demonstrated. It is proved that, even in the absence of image error, each model must be represented by a 2D surface in the index space. This places an unexpected lower bound on the space required to implement indexing and proves that no quantity is invariant for all projections of a model into the image. Theoretical bounds on the speedup achieved by indexing in the presence of image error are also determined, and an implementation of indexing for measuring this speedup empirically is presented. It is found that indexing can produce only a minimal speedup on its own. However, when accompanied by a grouping operation, indexing can provide significant speedups that grow exponentially with the number of features in the groups     

Web-based image indexing and retrieval in JPEG compressed domain

As the majority of content-based image retrieval systems operate on full images in pixel domain, decompression is a prerequisite for the retrieval of compressed images. To provide a possible on-line indexing and retrieval technique for those jpg image files, we propose a novel pseudo-pixel extraction algorithm to bridge the gap between the existing image indexing technology, developed in the pixel domain, and the fact that an increasing number of images stored on the Web are already compressed by JPEG at the source. Further, we describe our Web-based image retrieval system, WEBimager, by using the proposed algorithm to provide a prototype visual information system toward automatic management, indexing, and retrieval of compressed images available on the Internet. This provides users with efficient tools to search the Web for compressed images and establish a database or a collection of special images to their interests. Experiments using texture- and colour-based indexing techniques support the idea that the proposed algorithm achieves significantly better results in terms of computing cost than their full decompression or partial decompression counterparts. This technology will help control the explosion of media-rich content by offering users a powerful automated image indexing and retrieval tool for compressed images on the Web.J. Jiang: Contacting author     

Color Image Discriminant Models and Algorithms for Face Recognition

This paper presents a basic color image discriminant (CID) model and its general version for color image recognition. The CID models seek to unify the color image representation and recognition tasks into one framework. The proposed models, therefore, involve two sets of variables: a set of color component combination coefficients for color image representation and one or multiple projection basis vectors for color image discrimination. An iterative basic CID algorithm and its general version are designed to find the optimal solution of the proposed models. The general CID (GCID) algorithm is further extended to generate three color components (such as the three color components of the RGB color images) for further improvement of the recognition performance. Experiments using the face recognition grand challenge (FRGC) database and the biometric experimentation environment (BEE) system show the effectiveness of the proposed models and algorithms. In particular, for the most challenging FRGC version 2 Experiment 4, which contains 12 776 training images, 16 028 controlled target images, and 8014 uncontrolled query images, the proposed method achieves the face verification rate (ROC III) of 78.26% at the false accept rate (FAR) of 0.1%.      

Polyhedral object recognition by indexing

In computer vision, the indexing problem is the problem of recognizing a few objects in a large database of objects while avoiding the help of the classical image-feature-to-object-feature matching paradigm. In this paper we address the problem of recognizing three-dimensional (3-D) polyhedral objects from 2-D images by indexing. Both the objects to be recognized and the images are represented by weighted graphs. The indexing problem is therefore the problem of determining whether a graph extracted from the image is present or absent in a database of model graphs. We introduce a novel method for performing this graph indexing process which is based both on polynomial characterization of binary and weighted graphs and on hashing. We describe in detail this polynomial characterization and then we show how it can be used in the context of polyhedral object recognition. Next we describe a practical recognition-by-indexing system that includes the organization of the database, the representation of polyhedral objects in terms of 2-D characteristic views, the representation of this views in terms of weighted graphs and the associated image processing. Finally, some experimental results allow the evaluation of the system performance.     

Matching 3-D Models to 2-D Images

We consider the problem of analytically characterizing the set of all 2-D images that a group of 3-D features may produce, and demonstrate that this is a useful thing to do. Our results apply for simple point features and point features with associated orientation vectors when we model projection as a 3-D to 2-D affine transformation. We show how to represent the set of images that a group of 3-D points produces with two lines (1-D subspaces), one in each of two orthogonal, high-dimensional spaces, where a single image group corresponds to one point in each space. The images of groups of oriented point features can be represented by a 2-D hyperbolic surface in a single high-dimensional space. The problem of matching an image to models is essentially reduced to the problem of matching a point to simple geometric structures. Moreover, we show that these are the simplest and lowest dimensional representations possible for these cases.We demonstrate the value of this way of approaching matching by applying our results to a variety of vision problems. In particular, we use this result to build a space-efficient indexing system that performs 3-D to 2-D matching by table lookup. This system is analytically built and accessed, accounts for the effects of sensing error, and is tested on real images. We also derive new results concerning the existence of invariants and non-accidental properties in this domain. Finally, we show that oriented points present unexpected difficulties: indexing requires fundamentally more space with oriented than with simple points, we must use more images in a motion sequence to determine the affine structure of oriented points, and the linear combinations result does not hold for oriented points.     

Iteration-free clustering algorithm for nonstationary image database

Image database systems must effectively and efficiently handle and retrieve images from a large collection of images. A serious problem faced by these systems is the requirement to deal with the nonstationary database. In an image database system, image features are typically organized into an indexing structure, and updating the indexing structure involves many computations. In this paper, this difficult problem is converted into a constrained optimization problem, and the iteration-free clustering (IFC) algorithm based on the Lagrangian function, is presented for adapting the existing indexing structure for a nonstationary database. Experimental results concerning recall and precision indicate that the proposed method provides a binary tree that is almost optimal. Simulation results further demonstrate that the proposed algorithm can maintain 94% precision in seven-dimensional feature space, even when the number of new-coming images is one-half the number of images in the original database. Finally, our IFC algorithm outperforms other methods usually applied to image databases.