Skip to content

New Image-Description Guidelines Coming from ISO/IEC

2012 September 7

Image-description enthusiasts will be happy to learn that ISO and the IEC are preparing to issue a new set of guidelines pertaining to… well, image descriptions. It’s called “ISO/IEC TS 20071-11 – Information Technology — User Interface Component Accessibility – Part 11 Guidance for Text Alternatives for Images,” and, having just passed through the approval process, should be available in its final format shortly. The version linked here is the most recent public working draft (an untagged PDF, unfortunately), but I imagine that there will be few differences between this draft and the final version. It’s about 30 pages long and as standards go it isn’t terribly difficult to read or understand. Nonetheless, not everyone enjoys wading through standardspeak, so here is a brief summary.

The guidelines are aimed at authors and developers who want to describe static images found in electronic documents of all kinds. There is an explicit disclaimer that the guidelines do not apply to moving images, but you’ll find that a good deal of the advice can, in fact, be used when formulating video descriptions. And while the guidelines detail how to decide what to say in an image description, it is important to note that they do not show you how, exactly, to insert descriptions into electronic documents. That is, you need to look elsewhere for code examples. Two excellent resources are NCAM’s Effective Practices for Description of Science Content within Digital Talking Books and the W3C’s HTML5: Techniques for providing useful text alternatives.

ISO/IEC TS 20071-11 advocates a highly structured approach to providing both brief and lengthy image descriptions. The basic idea is summarized in Section 3.2:

“Initially, the structure identifies information about the whole image. It focuses on information that applies to the entire image. Because an image can have a vast amount of information, the structure breaks down the image into several parts (called image components) and focuses on identifying information about each part (or image component). Breaking down the image into several parts allows for focus on the details of those particular parts, resulting in more information about the image. An image component could be broken down further into additional image components.”

In other words, begin by broadly describing the entire image, then add more narrowly focused details as appropriate. Context is everything, so the vocabulary, level of detail and length of the description will largely be dictated by how the image is used in the document. These are not a new concepts, and DIAGRAM project partners have been following similar procedures for many years, but now they will be enshrined in an official ISO standard.

The requirements and recommendations for image descriptions are laid out in vast detail, beginning with the statement that there are three levels of importance to consider when deciding what to describe:

  • Essential information shall be presented either in the main document text (when referring to the image) or in the primary alternative text. NOTE: By placing essential information in the main document text (when appropriate) it ensures that all users (not just users with screen readers) will have access to this information.
  • Significant information shall be presented either in the primary alternative text or in secondary alternative text.
  • Because helpful information is only of interest to some of the users some of the time, it should not be placed in the primary alternative text. It may be placed in secondary alternative text or in a separate document that is linked from either the main document text or the primary alternative text.

The document also acknowledges that images often contain pictures of text, but it provides a strong statement against the general use of text in graphics when that text could otherwise be presented as true text.

It’s important to note that compliance with ISO standards is completely voluntary: they are not enforced by ISO or any other organization. (Read the ISO FAQ for more information.) ISO standards can be– and in some cases have been– adopted by governmental agencies or other regulatory bodies, in which case they are enforced according to the rules of those entities. On its own, then, ISO/IEC TS 20071-11 will have no legal weight or mandatory-usage conditions. However, ISO standards and guidelines do carry with them a certain degree of authority, so the fact that ISO is publishing a document about image descriptions gives the information in that document serious credibility. And generally speaking, the whole idea behind using or following specifications is that the consistency they provide eventually benefits the intended audience. In our specific case, one could say that if everyone who writes image descriptions follows the ISO-approved method, then the entire corpus of descriptions will eventually improve, thereby providing great benefit to people who rely on image descriptions in any context.

A close reading of ISO/IEC TS 20071-11 will undoubtedly reveal ideas and details with which you’ll both agree and disagree (for example, I’m not so sure I completely agree with the statements in section 6.3 regarding document flow). Is this document the final word on image descriptions? No. However, it does provide some excellent guidance, especially for those new to the process, on creating an image-description decision tree. And because it’s published by a respected standards body, it may eventually lead to a more unified, cohesive approach to writing image descriptions. When it’s available in final form, you’ll want to add it to your stack of resources.

Leave a Reply