Digital Image Access & Retrieval

The 33th Annual Clinic on Library Applications of Data Processing, held at the University of Illinois at Urbana-Champaign in March of 1996, addressed the theme of "Digital Image Access & Retrieval." The papers from this conference cover a wide range of topics concerning digital imaging technology for visual resource collections. Papers covered three general areas: (1) systems, planning, and implementation; (2) automatic and semi-automatic indexing; and (3) preservation with the bulk of the conference focusing on indexing and retrieval.published or submitted for publicatio

Structured Knowledge Representation for Image Retrieval

We propose a structured approach to the problem of retrieval of images by content and present a description logic that has been devised for the semantic indexing and retrieval of images containing complex objects. As other approaches do, we start from low-level features extracted with image analysis to detect and characterize regions in an image. However, in contrast with feature-based approaches, we provide a syntax to describe segmented regions as basic objects and complex objects as compositions of basic ones. Then we introduce a companion extensional semantics for defining reasoning services, such as retrieval, classification, and subsumption. These services can be used for both exact and approximate matching, using similarity measures. Using our logical approach as a formal specification, we implemented a complete client-server image retrieval system, which allows a user to pose both queries by sketch and queries by example. A set of experiments has been carried out on a testbed of images to assess the retrieval capabilities of the system in comparison with expert users ranking. Results are presented adopting a well-established measure of quality borrowed from textual information retrieval

[[alternative]]An Efficient Shape-Representation Method for Content Based Image Retrieval

計畫編號：NSC93-2213-E032-006研究期間：200408~200507研究經費：593,000[[abstract]]以內容為基礎之影像查詢(CBIR)的研究可分為特徵選取、物件表示以及結果比 對。假如以物件的外形輪廓表示物件的特徵，那麼邊緣點偵測就是抽取這類特徵的第 一個步驟。當找完了邊緣點後，一個好的物件表示法必須能夠克服物件在影像中的移 位、旋轉、以及放大或縮小等問題。甚至對於物件外形在一定程度內的損毀下也必須 能夠有好的比對結果。這些問題都是在利用物件外形特徵來表示物件時以及比對過程 中相當重要的議題。 因此本計畫將提出一個有效率及強健的以物件外形特徵為基礎的影像查詢系統。 我們使用一快速的邊緣點偵測演算法來偵測出影像中所有可能的邊緣點，並提出一新 的物件表示法—爬山式序列表示法(Mountain Climbing Sequence (MCS))。此表示法 對於前面所提之影像中的移位、旋轉、以及放大或縮小等問題都可以達到不變的效果。 另外，由於邊緣點的偵測就目前的研究經驗上並無法保証能夠找一物件的完整外形， 因此我們也將嘗試在現有的外形特徵表示法下，克服物件外形不完整抽取的情況，甚 至於在物件少部份被遮蔽的狀況也能得到好的比對結果。[[sponsorship]]行政院國家科學委員

Query processing of spatial objects: Complexity versus Redundancy

The management of complex spatial objects in applications, such as geography and cartography, imposes stringent new requirements on spatial database systems, in particular on efficient query processing. As shown before, the performance of spatial query processing can be improved by decomposing complex spatial objects into simple components. Up to now, only decomposition techniques generating a linear number of very simple components, e.g. triangles or trapezoids, have been considered. In this paper, we will investigate the natural trade-off between the complexity of the components and the redundancy, i.e. the number of components, with respect to its effect on efficient query processing. In particular, we present two new decomposition methods generating a better balance between the complexity and the number of components than previously known techniques. We compare these new decomposition methods to the traditional undecomposed representation as well as to the well-known decomposition into convex polygons with respect to their performance in spatial query processing. This comparison points out that for a wide range of query selectivity the new decomposition techniques clearly outperform both the undecomposed representation and the convex decomposition method. More important than the absolute gain in performance by a factor of up to an order of magnitude is the robust performance of our new decomposition techniques over the whole range of query selectivity

Effective Method of Image Retrieval Using Markov Random Field with Hough Transform

The emergence of multimedia technology and the rapidly expanding image collections on the database have attracted significant research efforts in providing tools for effective retrieval and management of visual data. The need to find a desired image from a large collection. Image retrieval is the field of study concerned with searching and retrieving digital image from a collection of database .In real images, regions are often homogenous; neighboring pixels usually have similar properties (shape, color, texture) Markov Random Field (MRF) is a probabilistic model which captures such contextual constraints. Hough Transform method is used for detecting lines in binary images. Spatially extended patterns are transformed to produce compact features in a parameter space. The main advantages of using the HT is, it treats each edge point independently this means that the parallel processing of all points is possible which is suitable for real-time applications

Symbolic and Visual Retrieval of Mathematical Notation using Formula Graph Symbol Pair Matching and Structural Alignment

Large data collections containing millions of math formulae in different formats are available on-line. Retrieving math expressions from these collections is challenging. We propose a framework for retrieval of mathematical notation using symbol pairs extracted from visual and semantic representations of mathematical expressions on the symbolic domain for retrieval of text documents. We further adapt our model for retrieval of mathematical notation on images and lecture videos. Graph-based representations are used on each modality to describe math formulas. For symbolic formula retrieval, where the structure is known, we use symbol layout trees and operator trees. For image-based formula retrieval, since the structure is unknown we use a more general Line of Sight graph representation. Paths of these graphs define symbol pairs tuples that are used as the entries for our inverted index of mathematical notation. Our retrieval framework uses a three-stage approach with a fast selection of candidates as the first layer, a more detailed matching algorithm with similarity metric computation in the second stage, and finally when relevance assessments are available, we use an optional third layer with linear regression for estimation of relevance using multiple similarity scores for final re-ranking. Our model has been evaluated using large collections of documents, and preliminary results are presented for videos and cross-modal search. The proposed framework can be adapted for other domains like chemistry or technical diagrams where two visually similar elements from a collection are usually related to each other