ISO/IEC 20071-11:2019

INTERNATIONAL ISO/IEC
STANDARD 20071-11
First edition
2019-12
Information technology — User
interface component accessibility —
Part 11:
Guidance on text alternatives for
images
Technologies de l'information — Accessibilité du composant interface
utilisateur —
Partie 11: Lignes directrices pour les textes alternatifs pour images
Reference number
©
ISO/IEC 2019
© ISO/IEC 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO/IEC 2019 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Text alternatives and related definitions . 1
3.2 Image and related definitions . 2
3.3 Image types and related definitions . 3
3.4 Image content and related definitions. 3
3.5 Information relationship definitions . 4
3.6 Information type definitions . 4
3.7 Importance and related definitions . 5
4 Text alternatives for images . 6
4.1 Uses of text alternatives . 6
4.2 Presenting text alternatives . 7
4.2.1 General. 7
4.2.2 Text alternatives within the main body of text . 7
4.2.3 Primary alternative text . . 7
4.2.4 Secondary alternative text . 8
5 Procedure for creating text alternatives . 8
6 Identifying the types of image . 9
6.1 General . 9
6.2 Drawings . 9
6.3 Photographs .10
6.4 Diagrams .10
6.5 Maps .10
6.6 Computer-generated illustrations .11
6.7 Composite images .11
6.8 Identifying image type in text alternatives .11
6.8.1 Identifying the image type of single images .11
6.8.2 Identifying image type of composite images with separately addressable
components .11
7 Identifying the purpose of the image .12
7.1 Introduction to purposes .12
7.2 Informative purposes .12
7.3 Control purposes .13
7.4 Decorative purposes.13
7.4.1 Decorative images that convey affective information .13
7.4.2 Decorative images with minimal information value .13
7.5 Formatting purposes .14
7.6 Identifying purpose in text alternatives .14
7.6.1 Describing the purpose .14
7.6.2 Stating the purpose briefly .14
7.6.3 Avoiding redundancy with captions .15
7.6.4 Considering the context of use.15
7.6.5 Considering both objective and subjective purposes .15
7.6.6 Text alternatives for images used for formatting purposes .15
7.6.7 Further information for images used for informative purposes .15
7.6.8 Further information for images used for control purposes .16
8 Identifying the image components .16
8.1 Images and image components .16
© ISO/IEC 2019 – All rights reserved iii

8.2 Text components .16
8.3 Uniquely identifying image components .16
8.4 Structuring information about images and their components .17
8.5 Dealing with image complexity .18
8.5.1 Use of image components .18
8.5.2 Textual information in images .18
8.5.3 Information about whole images .19
8.5.4 Information about image components .19
9 Identifying the information (content) presented by the image .19
9.1 Content of an image or its components .19
9.2 Subjective content .19
9.3 Objective content .20
9.4 Relationship content .21
9.4.1 Relationships .21
9.4.2 Actions .21
9.4.3 Logical relationships .22
9.4.4 Temporal relationships .22
9.4.5 Physical (spatial) relationships .23
9.5 Interaction content .24
9.6 Analysing the information presented by an image .24
10 Evaluating the importance of the information about the image .25
10.1 Importance is context dependent .25
10.2 Importance .25
10.2.1 Levels of importance .25
10.2.2 Essential information.25
10.2.3 Significant information .
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