A man may have eyes but may not always see, at least not clearly. In a similar way, taking perfect vision for granted when building a user interface can betray a designer's short-sightedness.
But the need to display information on screens clearly, for all types of users, is growing.
Over the next few years, users will need to use a range of self-service terminals to obtain access to goods and services, according to Tiresias, the Royal National Institute for the Blind's (RNIB) research unit. This will include ticket machines, information terminals, cash machines and computer terminals shared between employees.
John Gill, chief scientist at the RNIB, said the interfaces of these terminals tend to be designed for a "typical" user, but have to be used by people with a wide range of abilities.
"Therefore, the ability to customise the terminal to suit an individual's needs would make the terminals usable by a wider range of people," he said.
The Tiresias group provides guidelines for improving accessibility for designers of information and communication technology systems.
The group is developing a smartcard technology standard called Special Needs Application Program Interface (Snapi) that could be used to automatically configure screens depending on the user's disability.
When a card containing Snapi data is put into a computers it informs the device on how to communicate with the user. This can enable various accessibility modes such as a high-contrast display or increased font size.
When the transaction is complete, the computer returns to its default settings. The card could also be developed for use with any computer system with a smartcard reader.
Gill gave the example of a lady with poor vision using a public computer in a library. The librarian finds it time consuming to set up the computer terminal to display information appropriately for the customer's needs.
"The solution is that her special needs could have been stored on her library card. She just inserts the card into the computer terminal, and it automatically adjusts the size of icons and text, the colours and type of cursor to suit her needs," said Gill.
When she has finished her session, she removes the library card, and the computer automatically reverts to its normal settings. If she wants to change any of her special-needs settings, this can be done on the terminal and stored back on her library card, said Gill.
This is just one example of a situation where the user would find it helpful to reconfigure the user interface to suit their individual needs. Other potential applications areas include transport, finance, television, government and local government and hot-desking environments.
The Snapi card offers many different ways of adapting the PC screen including: font colour and type, background colour, language, and mouse and keyboard settings. It can also offer screen enhancement features such as magnification and colour avoidances, and can change speech, audio, kiosk, braille and biometric preferences.
The work on developing a system for coding these user requirements has been completed, and Snapi is now a formal European and British standard. This coding system has been incorporated in the ITSO specification for smartcard ticketing for public transport in the UK. The standard is also recommended in the e-GIF specification, which is published by the Cabinet Office, for all new cards issued by government departments, local government or any agency of government.
Currently being converted into an international standard is a specification on how to store information about an individual on a card. This specification includes the coding of user requirements according to the European standard. This means that any citizen card in accordance with the international standard will be compatible with the Snapi system.
The software to reconfigure Microsoft Office has already been developed. In this case, all the accessibility options associated with Windows XP can be coded on the card, and the system returns to its default settings as soon as the card is removed from the reader.