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Accessibility is a term used to describe how a multimedia product is designed to be accessible to as many users as possible.

Colour deficiency: For example, some computer users will not be able to distinguish certain colours. A texture or pattern on a button or menu can help users with a colour deficiency pick out items on the screen.

The term visual impairment is used to describe partial sight or blindness. You can help users who are partially sighted by using high contrast and providing alternative pages that use a large text size and a suitable method for accessing that larger text.

Blind users will be able to use a multimedia package by making use of specialist input devices and screen reading software. Multimedia software should be designed to be compatible with screen reading software.

Hearing impairment or deafness will prevent some users listening to audio.

You can help users with hearing impairments by:

• Providing a transcript of the audio file in text form.
• Providing a subtitled version of a video clip.
• Supplementing interface audio with visual notifications that a button has been pressed or a screen is about to load.

WCAG 1.0 - Web Content Accessibility Guidelines

Web Content Accessibility Guidelines (WCAG) 2.0 defines how to make Web content accessible to people with disabilities. It addresses a wide range of disabilities including visual, auditory, physical, speech, cognitive, language, learning and neurological disabilities.

Cross-platform compatibility

It is also very important that the information is accessible on different hardware devices and platforms. The World Wide Web Consortium (W3C) supports the development of standards that will make information hosted on the web available across all devices.

HTML 5 and web standards

HTML5 is a markup language used for structuring and presenting content on the world wide web. It has been developed to encourage greater interoperability between devices. The new standard incorporates features like video playback and drag-and-drop that have been previously dependent on third-party browser plug-ins (see below).

Accessibility also considers the device and operating system the end user will use to access the multimedia product. Accessible multimedia products will be available on mobile phones, tablet computers and personal computers through an array of different browsers and operating system software.

Plug-ins

A plug-in is a piece of software that enables an application or program to do something it couldn't do by itself. One of the more common plug-ins is Adobe Flash Player. Without flash player you won't, for example, be able to view many video players that are embedded into web pages. Numerous plug-ins are available to extend the functionality of web browsers, from Adobe Acrobat reader to Sun's Java, allowing us to view pdf files and run scripts written in Java.

Due to security issues arising from third party plug-ins, many vendors no longer support them and prefer to use HTML 5. Often scammers will attempt to make malware look like legitimate plug-ins.

Portable Document Formats (PDFs)

PDFs are a file format that captures all the elements of a printed document as an electronic file that you can view, navigate, print, forward or share. PDFs are created using specialised PDF software, for example Adobe Acrobat.

PDFs improve cross platform compatibility as you can freely download the software required to view and use the file. PDF reading software is device independent and will work across all platforms. PDF files are especially useful for documents such as magazine articles, brochures or flyers in which you want to preserve the original appearance and layout online regardless of the platform that it is viewed on.

Optimised file formats

File optimisation is the process of modifying a computer file to make it use less system resources. This will allow files to download and run faster with less memory and processing requirements. Digital development files are often compressed to aid optimisation.

Popular optimised image formats .JPEG and .GIF are cross platform, thus improving compatibility between software and hardware platforms.

Compression is taking original uncompressed data and compressing it so the result requires less data. See the revision guide on digital data for more information on lossy and lossless compression.

When network bandwidth is an issue, such as on the internet, it is important to optimise files. Some common internet file formats are listed below: