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Spatial-match Iconic Image Retrieval with Ranking in Multimedia Databases

Spatial-match Iconic Image Retrieval with Ranking in Multimedia Databases. Jae-Woo Chang and Yeon-Jung Kim Chonbuk National University. Introduction. In this paper a content-based image retrieval system for iconic images is developed

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Spatial-match Iconic Image Retrieval with Ranking in Multimedia Databases

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  1. Spatial-match Iconic Image Retrieval with Ranking in Multimedia Databases Jae-Woo Chang and Yeon-Jung Kim Chonbuk National University

  2. Introduction • In this paper a content-based image retrieval system for iconic images is developed • Iconic images: image objects are represented by a meaningful graphic description

  3. Introduction • Two methods are developed: • Spatial-match Representation Supporting Ranking with Minimum Bounding Circle:SRC • Spatial-match Representation Supporting Ranking with Minimum Bounding Rectangle:SRR • Represent spatial relationships (directional and positional) between objects in an image • Allow ranking of retrieval results by using an inverted file structure as access method

  4. Related Work – 9DLT scheme • Scheme to describe directional relationships between objects • Direction codes are denoted by nine integers (0,…,8) according to direction of a target object to reference object ( R ) • Spatial relationships are represented by triple (object A, object B, DAB), where DAB means the 9DLT directional code

  5. Related Work – SMR scheme • Objects are represented by Minimum Bounding Rectangles (MBR) • Topological operator PX(PY) denotes relationships between projections p and q of objects A and B over X-axis (Y-axis) • In total there are 15 topological operators (Figure shows 7) • Example: (A, B, 0, 0) indicates that A is far away from B

  6. The SRC scheme • Objects are represented by Minimum Bounding Circle (MBC) • Can represent spatial relationships between objects, based on projections of objects on X-axis and Y-axis

  7. The SRC scheme • Define 7positional operators: FA(Far-away), DJ(Disjoint), ME(Meet), OL(Overlap), CL (is-included-by), IN(Include), SA(Same)

  8. The SRC scheme • Spatial relations RAB between objects can be determined as follows, where DM means distance multiplier, radT and radR are the radius of the MBCs and

  9. The SRR scheme • Objects are represented by Minimum Bounding Rectangle (MBR) • Can represent spatial relationships between objects, based on projections of objects on X-axis and Y-axis

  10. The SRR scheme • Define 7 positional operators (FA, DJ, ME, OL, IN, SA) between 2 objects for the i-axis, where i signifies X- or Y-axis

  11. The SRR scheme • Combine 1-dim. Relationships and into two-dimensional relation RAB between 2 objects • Finally (for SRC and SRR) define spatial string of 2 objects A and B: • (where Ang: 0-360o)

  12. Similar Topological Operators • classify 7 topological operators into two groups, i.e. disjoint and include and order them according to their similarities • disjoint: FA-DJ-ME-OL • include: CL-SA-IN • Only OL of disjoint group has its similarity with operators in include group (i.e. CL and IN) • Similarity distance between 2 operators:number of edges between their nodes

  13. Ranking • New weighting scheme which can rank the results based on the angle between objects and their positional operator • For 2 spatial strings and a weight is calculated by: • if 2 objects from each string are the same (i.e. A=QA, B=QB) • and angle difference (i.e. |Ang-QAng|) < threshold ( ), then: Where sim_dis(RAB,QAB) is similarity distance between RAB and QAB and thres_dis is threshold distance

  14. Index File • Inverted file is used as access method to support ranking and fast retrieval • Consider the spatial string (A,B,OL,234o) as example, then string ‘AB’ serves as the key • #SSTR: numberof spatial strings with the corresponding key • SrartAddr: address of Posting File record for a given key • RAB:topological operator of the spatial string • Ang: indicates angle • RecID:identifier of an iconic image related with the spatial string

  15. Retrieval • Make spatial strings(QA,QB,QRAB,QAng) from iconic query image • Construct key from each spatial string and searchindex file • if no such keyexists -> no image in database satisfy query • otherwisereadPosting File entries • Obtain a pair (WXY , ImageID) by comparing (QRAB, QAng) with all spatial strings in Posting File record • Compute for each (WXY, ImageID) pair having the sameImageID • Rankretrieved images in decreasing order of WPQ

  16. Performance Analysis • SRC and SRR schemes are comparedwith 9DLT and SMR in terms of retrieval effectiveness and system efficiency • SRC and SRR schemes show higher recall and precision and much fasterretrieval efficiency than 9DLT and SMR • SRR is better in terms of retrieval effectiveness • SRC is better in terms of system efficiency • Result:SRR and SRC are suitable for multimedia systems which requireranking as well as fast retrieval

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