1、BSI Standards Publication BS ISO/IEC 15938-13:2015 Information technology Multimedia content description interface Part 13: Compact descriptors for visual searchBS ISO/IEC 15938-13:2015 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO/IEC 15938-13:2015. The UK
2、 participation in its preparation was entrusted to Technical Committee IST/37, Coding of picture, audio, multimedia and hypermedia information. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the nece
3、ssary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 85131 5 ICS 35.040 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard
4、 was published under the authority of the Standards Policy and Strategy Committee on 30 September 2015. Amendments issued since publication Date Text affectedBS ISO/IEC 15938-13:2015 Information technology Multimedia content description interface Part 13: Compact descriptors for visual search Techno
5、logies de linformation Interface de description du contenu multimdia Partie 13: Descripteurs compacts pour recherche visuelle INTERNATIONAL STANDARD ISO/IEC 15938-13 Reference number ISO/IEC 15938-13:2015(E) First edition 2015-09-01 ISO/IEC 2015 BS ISO/IEC 15938-13:2015ii ISO/IEC 2015 All rights res
6、erved COPYRIGHT PROTECTED DOCUMENT ISO/IEC 2015, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or
7、an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrig
8、htiso.org www.iso.org ISO/IEC 15938-13:2015(E)BS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E)Foreword v Introduction vi 1 Scope . 1 2 T erms and definitions . 1 3 Symbols and abbreviated terms . 2 3.1 General . 2 3.2 Abbreviations . 2 3.3 Arithmetic operations . 3 3.4 Logical operators 3 3.5 Relati
9、onal operators . 3 3.6 Bitwise operators 4 3.7 Assignment . 4 3.8 Mnemonics . 4 3.9 Constants . 4 3.10 Functions 4 4 CDVS syntax 5 4.1 Binary representation syntax . 5 4.2 Descriptor component semantics . 6 5 CDVS encoding . 9 5.1 General . 9 5.2 Original image preprocessing 9 5.3 Interest point det
10、ection . 9 5.3.1 Introduction . 9 5.3.2 Scale space construction . 9 5.3.3 Detection of scale-space extrema .10 5.3.4 Coordinate refinement to subpixel precision. .14 5.3.5 Transformation of coordinates and scale to the converted image resolution .17 5.3.6 Elimination of duplicates .17 5.3.7 Orienta
11、tion Assignment 17 5.3.8 Interest point characteristics .19 5.4 Local feature selection .19 5.4.1 Operation .19 5.4.2 Descriptor components 20 5.5 Local feature description 21 5.6 Local feature descriptor aggregation 23 5.6.1 Operation .23 5.6.2 Descriptor components 26 5.7 Local feature descriptor
12、compression .27 5.7.1 Operation .27 5.7.2 Descriptor components 30 5.8 Local feature location compression .31 5.8.1 Operation .31 5.8.2 Descriptor components 36 5.9 Encoding order of compressed local feature descriptors and relevance bits 37 5.10 Computation of the number of compressed local feature
13、 descriptors at different image descriptor lengths .37 Annex A (informative) CDVS encoder organization .38 Annex B (normative) C oefficients for c oor dinat e r efinement 39 Annex C (normative) Probability values for the feature selection .41 Annex D (normative) PCA projection matrix for local featu
14、re descriptor aggregation .44 ISO/IEC 2015 All rights reserved iii Contents PageBS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E)Annex E (normative) GMM parameters for local feature descriptor aggregation .55 Annex F (normative) Gaussian function selection parameters for local feature descriptor aggr
15、egation 135 Annex G (normative) Bit selection masks for local feature descriptor aggregation .136 Annex H (normative) Scalar quantization thresholds for local feature descriptor compression .138 Annex I (normative) Histogram count arithmetic coding model probabilities 142 Annex J (normative) Histogr
16、am map arithmetic coding model probabilities 144 Annex K (informative) CDVS decoding .145 iv ISO/IEC 2015 All rights reservedBS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form
17、 the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC te
18、chnical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
19、 The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of document should be noted. This document was drafted in accordance with the edi
20、torial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Details of any p
21、atent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.
22、For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible f
23、or this document is ISO/IEC JTC 1, Information technology, SC 29, Coding of audio, picture, multimedia and hypermedia information. ISO/IEC 15938 consists of the following parts, under the general title Information technology Multimedia content description interface: Part 1: Systems Part 2: Descripti
24、on definition language Part 3: Visual Part 4: Audio Part 5: Multimedia description schemes Part 6: Reference software Part 7: Conformance testing Part 8: Extraction and use of MPEG-7 descriptions Part 9: Profiles and levels Part 10: Schema definition Part 11: MPEG-7 profile schemas Part 12: Query fo
25、rmat Part 13: Compact descriptors for visual search ISO/IEC 2015 All rights reserved vBS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E) Introduction This International Standard, also known as “Multimedia Content Description Interface,” provides a standardized set of technologies for describing multim
26、edia content. It addresses a broad spectrum of multimedia applications and requirements by providing a metadata system for describing the features of multimedia content. The following are specified in this International Standard: Description schemes (DS) describe entities or relationships pertaining
27、 to multimedia content. Description schemes specify the structure and semantics of their components, which may be Description Schemes, descriptors, or datatypes. Descriptors (D) describe features, attributes, or groups of attributes of multimedia content. Datatypes are the basic reusable datatypes e
28、mployed by description schemes and descriptors. Systems tools support delivery of descriptions, multiplexing of descriptions with multimedia content, synchronization, file format, and so forth. This International Standard is subdivided into 13 parts: Part 1 Systems: specifies the tools for preparing
29、 descriptions for efficient transport and storage, compressing descriptions, and allowing synchronization between content and descriptions. P a r t 2 D e s c r i p t i o n d e f i n i t i o n l a n g u a g e: specifies the language for defining the International Standard set of description tools (DS
30、s, Ds, and datatypes) and for defining new description tools. Part 3 Visual: specifies the description tools pertaining to visual content. Part 4 Audio: specifies the description tools pertaining to audio content. Part 5 Multimedia description schemes: specifies the generic description tools pertain
31、ing to multimedia including audio and visual content. Part 6 Reference software: provides a software implementation of the International Standard. Part 7 Conformance testing: specifies the guidelines and procedures for testing conformance of implementations of the International Standard. Part 8 Extr
32、action and use of MPEG-7 descriptions: provides guidelines and examples of the extraction and use of descriptions. P a r t 9 P r o f i l e s a n d l e v e l s: provides guidelines and standard profiles. P a r t 1 0 S c h e m a d e f i n i t i o n: specifies the schema using description definition la
33、nguage. P a r t 1 1 P r o f i l e S c h e m a s: listing of profile schemas using description definition language. Part 12 Query format: contains the tools of the MPEG Query Format (MPQF). Part 13 Compact descriptors for visual search: specifies an image description tool for visual search applicatio
34、ns.vi ISO/IEC 2015 All rights reservedBS ISO/IEC 15938-13:2015Information technology Multimedia content description interface Part 13: Compact descriptors for visual search 1 Scope The structure of this part of ISO/IEC 15938 is as follows. Clauses 2 and 3 specify the terms, abbreviations, symbols, a
35、nd conventions used in the International Standard. Clause 4 specifies the binary representation syntax and descriptor component semantics for a CDVS image descriptor. Clause 5 specifies the extraction and encoding process for a CDVS image descriptor. Annexes A-J specify information relevant to the e
36、ncoding process of Clause 5. Annex K contains an informative description of the decoding process of a CDVS image descriptor. This part of the MPEG-7 standard specifies an image description tool designed to enable efficient and interoperable visual search applications, allowing visual content matchin
37、g in images. Visual content matching includes matching of views of objects, landmarks, and printed documents, while being robust to partial occlusions as well as changes in viewpoint, camera parameters, and lighting conditions. 2 T erms a nd definiti ons For the purposes of this document, the follow
38、ing terms and definitions apply. 2.1 image descriptor descriptor extracted from one image 2.2 image descriptor length size of an image descriptor in bytes Note 1 to entry: This International Standard specifies six average (i.e. over a large number of images) image descriptor lengths, i.e. 512 bytes,
39、 1024 bytes, 2048 bytes, 4096 bytes, 8192 bytes, and 16384 bytes, and the encoding process for each image descriptor length. 2.3 original image input image to the image descriptor encoder 2.4 converted image image which is a spatially resampled version of the original image and from which the image
40、descriptor is extracted 2.5 pixel indexable element of the original image or the converted image, comprising spatial coordinates and a luminance value 2.6 interest point point in an image showing detection stability under local and global perturbations in the image domain, including perspective tran
41、sformations, changes in image scale, and illumination variations INTERNATIONAL ST ANDARD ISO/IEC 15938-13:2015(E) ISO/IEC 2015 All rights reserved 1BS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E) 2.7 local region area in an image in the neighbourhood of an interest point, used to generate local fea
42、ture descriptors 2.8 cell each of the 4x4 subdivisions of a local region 2.9 cell histogram histogram of gradients computed from the cell 2.10 local feature descriptor descriptor of a local region, computed from the cell histograms 2.11 global descriptor aggregation of local feature descriptors into
43、 a compact representation of the image 2.12 compressed local feature descriptor compressed representation of a local feature descriptor 2.13 interest point coordinate horizontal and vertical pixel coordinates indicating the position of an interest point in the converted image resolution, rounded to
44、the nearest integer 2.14 location quantization factor size of the blocks of the spatial grid superimposed on top of the converted image in order to obtain quantized interest point coordinates values 2.15 histogram map binary representation of the converted image scaled down by the location quantizat
45、ion factor, indicating whether each bin generated through the superimposition of the spatial grid on top of the converted image is populated with at least one interest point 2.16 histogram count vector indicating the number of interest points that populate each non-empty bin generated through the su
46、perimposition of a spatial grid on top of the converted image 3 Symbols and abbreviated terms 3.1 General NOTE The mathematical operators used in this part of ISO/IEC 15938 are similar to those used in the C programming language. Unless otherwise indicated, all the arithmetic operations are performe
47、d with real values. Numbering and counting conventions generally begin from 0. 3.2 Abbreviations CDVS Compact Descriptors for Visual Search LoG Laplacian-of-Gaussian2 ISO/IEC 2015 All rights reservedBS ISO/IEC 15938-13:2015ISO/IEC 15938-13:2015(E) MPEG Moving Picture Experts Group MPEG-7 ISO/IEC 159
48、38 3.3 Arithmetic operations + Addition - Subtraction (as a binary operator) or negation (as a unary operator) + Increment by 1, i.e. x+ is equivalent to x=x+1 - Decrement by 1, i.e. x- is equivalent to x=x-1 += Increment by value, i.e. x+=y is equivalent to x=x+y -= Decrement by value, i.e. x-=y is
49、 equivalent to x=x-y * Multiplication (in binary representation syntax and pseudo-code) or convolution (elsewhere) Multiplication Multiplication / Division Division % Modulo operator 3.4 Logical operators | Logical OR Logical OR & Logical AND Logical AND ! Logical NOT 3.5 Relational operators Greater than = Greater than or equal to Greater than or equal to Less than = Less than or equal to Less
