- From: Stella O'Brien <smo-brien@lioness.demon.co.uk>
- Date: Wed, 12 Aug 1998 15:56:12 +0000
- To: w3c-wai-eo@w3.org
- Cc: peter.croasdale@bbc.co.uk
Title: Basic Guide to Accessible Web Design: fuller Author: Stella O'Brien Version: 2 Status: Draft Date last modified: 10th August 1998 1 Introduction 2 Supply text versions of visuals 3 Provide access to audiovisual material 4 Allow alternative input 5 Make text easy to scan 6 Make text easy to read 7 Provide easy navigation and links 8 Use accessible layout 9 Test the accessibility 10 Get more information 1 Introduction Graphics, sounds, and moving images are powerful communication tools. Use them, but do not lose the audiences that cannot see, hear, or interact with them. Design your site so that it is faster and easier to use for people with portable web devices, anyone with low bandwidth connections, and users with disabilities. This basic guide introduces some of the simple and cost-effective ways you can reach this wider audience. 2 Supply text versions of visuals Good visuals are very powerful, but not everybody can see them. Text can be spoken or converted into braille. Well written text alternatives communicate the content or purpose of a picture or display to people who have no access to them. A simple picture might only need a concise description to outline what it illustrates or does (if it is a graphical link). Provide a fuller description if necessary. Frequently, you need to display data summaries in the form of a diagram, graph, or pie chart. For example, your business web may allow you to visualise spreadsheet projections by means of animations. The complexity of this material means that you need to provide (say) a link to a full, text version of the data summary, and the raw data. Explain how you interpeted the data. Highlight any comparisons which are obvious in the display, such as a difference in annual sales figures. The information is now accessible to people who can not see the visual representations. 3 Provide access to audiovisual material Audio is a rich medium which is not available to deaf people, users in a noisy environment, or those who have the sound turned off. Provide a text version of sound or speech clips which stand alone, or which accompany a visual presentation. Include a description of all relevant sounds. Provide both audio and text descriptions of dynamic visuals such as movies, or animations. Use audio and text to make visual cues explicit. Draw attention to, and describe, significant action. Important auditory and visual information is now available to users who have partial or no access to the original material. 4 Allow alternative input Not everybody has the physical dexterity or acuity of vision needed to use a mouse or tracker ball. The choice of input should be determined by the user's preferences and technical resources. Voice control is easier if the navigation commands, name of links, fields etc. are simple and distinctive. Keyboard access is the only way some users can interact with a page. The user-friendly author ensures that information displays such as forms and imagemaps are accessible to alternative inputs. 5 Make text easy to scan Even for sighted people with large monitors, it takes longer to read online text than print. Users scan text, picking out keywords and sentences and ignoring those areas which do not interest them. Many users find it difficult to manipulate long, scrolling pages. They want the text to be clear, short, and relevant. It is harder for blind users or people with small display screens to scan for interesting material. Users of speech browsers or screen readers scan a speech stream to listen for cues to relevant information. An organised framework of summaries, headings, and lists promotes scanning for users who read or listen. The author can help by using proper HTML markup to emphasise the structure of the page. The framework helps users to navigate through a page, and to decide whether they want to follow a link or to read a full document. 6 Make text easy to read Page activity should be initiated by the user, not enforced by the author. For example, the auto-updating of a page can be disorienting for some people who use screen-readers. It is a mystery to users who have cognitive disabilities and do not understand why the page has changed when they did not request the action. Request users' permission before refreshing a page. Moving text is difficult to read for several categories of users. Allow users to freeze movement. Complex background images and colours obscure text and make it difficult to read for people with vision impairments. So do poor colour contrasts; white text on a pale grey background is difficult to read and to print. Some people need large fonts or a zoom facility to read a page more comfortably. User-friendly authors use relative sizing and positioning (e.g., a percentage of the default size) rather than absolute sizes or positions (e.g., pixels or points) for both fonts and graphics. 7 Provide easy navigation and links Navigation aids should be consistent in name, style, position, and accessibility throughout a site. Users need constant, easy access to i) distinctive information about their current position (aids bookmarking) ii) the home page and iii) a choice of overviews of the site's structure and contents. This ease of access facilitates current navigation, and makes it easier to return in the future because bookmarks have distinctive names. Provide meaningful names for links so that users have a clear idea of the content of a link, and where it will take them. 8 Use accessible layout Traditional layout practices are inherited from print media. When the techniques are misused to present a web page, they can be a barrier to making information accessible. Use layout which supports users who want to manipulate the structure in a way that suits their personal preferences, and technical resources. 9 Test the accessibility Test the web site with several browsers, in various modes (e.g., with graphics loading turned off; or without plug-ins), and on different monitors. The user-friendly author ensures that information displays such as forms and imagemaps are accessible to alternative inputs (e.g., keyboard rather than mouse). Check that interacting with the page is possible without using a mouse. Evaluate the site with an automated analysis tool which also checks for compatability with older versions of browsers. Make sure the web page still communicates the relevant information. 10 Get more information For updated versions of this card visit ***. For more detailed guidelines, fuller examples, and other useful techniques see ***.
Received on Wednesday, 12 August 1998 10:59:44 UTC