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Although the number of computers in households is growing at a phenomenal rate, they are still complex and expensive pieces of equipment that can be difficult for the average user to get to grips with.
Virtually all families in the UK own a television and it is the main source of information and entertainment in the household. Interactive Digital Television (iDTV) is undoubtedly going to become a popular way of viewing information contained on websites.
In principle it is easy for broadcasting companies to tie in information presented on screen to further, more detailed data within a website. Pressing a button on the remote control could access this data. Television, including digital TV, is regulated by the ITC, making these guidelines an additional source of guidance for the developers of websites.
Access to interactive pages via a television is achieved using either an in-built modem or a ‘set-top box’ (STB) attached to a cable television network. These relay any requests for pages through their system and out onto security systems via the Internet.
At present there is no clear standard for producing and formatting information for this medium. Navigation through a website on the TV is done through either a television remote control or a keyboard. Be aware that a website designed for accessing via a PC may not work on a television set or be available on a particular platform.
5.2.1 General
As many as two in three television viewer’s users may not have surfed the web previously using a computer. Therefore keep everything simple and clear. Don’t think of them as web pages; think instead of the way TV graphics look and feel. This is what users expect. Phrases like ‘click here to…’ are not appropriate in a mouse-less environment. Where possible, refer to a ‘service’ rather than a ‘site’. Although the contents are built using Internet technologies and may be re-purposed from a website, viewers who have not experienced the Internet may be confused by the use of Internet terminology.
This example of a screenshot from the UK online Interactive service illustrates the power of simplicity.
5.2.2 Three main TV-friendly principles
Three main principles are the key to making TV-friendly websites.
Readability
The size of the fonts used by set-top boxes to render text on the TV needs to be larger than those rendered by web browsers, simply because people are watching TV from a lot further away than they are when viewing their computer monitors.
The user can enlarge the size of the text displayed by some set-top boxes (to improve readability on small TV sets), but the user cannot of course change the size of the window used for the general display (PC browser windows can be resized manually).
Simplicity
Human-factors research has shown that for most computing tasks the threshold of frustration is around 10 seconds. Web page designs employing complex layouts and ‘pretty’ graphics just will not work. Whilst some iDTV services use high-speed access to the Internet, phone line connections represent the only option for many users. Therefore, it is recommended that HTML pages should not exceed 50kB in size. They cannot include dozens of links where this can be avoided. Kiosk-like navigation (with large on-screen buttons) is recommended, being more intuitive than computer menus.
Television users do not have a mouse so imagine what it is like navigating around the page using only arrow keys. Frames and complex tables are not possible.
Avoid writing long pages: remember that the normal user will saturate their cognitive capacity if they have more than seven things to look at. Viewers are not used to scrolling, so it is entirely possible that items below the viewable area will be completely missed. If you cannot say it in 40 words - then do not use DTV.
Entertaining content
Televisions are far less business-like than computers. Users expect to be entertained as well as educated or informed. Boredom thresholds can be quite high, and this is typified by the viewing culture of channel hopping at the press of a single button. This is likely to be the fate of dry content that does not capture the imagination or encourage the viewer to read on. Keep detail to a minimum - if you cannot say it in 40 words - then this may not be the right medium - remembering to provide back buttons to return the viewer to the page they have just left.
5.2.3 Design
Design guidelines can be summarised in ten rules that can be applied to any of the three TV-friendly principles:
5.2.4 Screen sizes
Scrolling is not simple or even possible for TV viewers. Most TV browsers will not support horizontal scrolling so pages that exceed the display window width may need to be reformatted to fit in. This can have unexpected effects on page layouts and may even result in parts of the page not being displayed at all.
Vertical scrolling is supported on most TV browsers, but viewers may miss items below the viewable area if they are not expecting them to be there. Examples of actual screen sizes are as follows:
5.2.5 Colours
Colours for TV need to be PAL safe. This means developers should avoid using RGB values including 0-16 and 236-256. This can be done in, for example, Adobe Photoshop using the Levels function. Using 90 per cent of the true colour will reduce colour bleed and distortion.
Colours displayed on TV look a lot brighter and more saturated than they do on a computer monitor, and certain colours when placed in close proximity to each other can cause effects on neighbouring elements such as jittering (visible movement), chroma crawl (colour smearing) and interference. Try and use web safe colours for Liberate platforms.
Always check the colours on a TV before committing to a whole series of pages. Keep small items such as icons greyscale or mono as colour tends to bleed and distort on the TV. Some transcoders attempt to adjust colours on the fly to ensure that they are broadcast safe, but some combinations may still cause problems and different platforms may behave differently.
Overly bright colours may be limited by transmitter technology, resulting in grey, patchy colours.
5.2.6 Text
It is harder to read text on a TV screen. It takes a lot more concentration and can take up to 25% longer to read. The optimum common text font is a sans serif font of size 12pt. Where the platform has a transcoder (Liberate and Netgem) this will be automatically increased by 50 per cent to 18pt. Fonts are limited to those few available in the set top box (STB) so keep text clear and concise.
5.2.7 Graphics
Authors should always present all images in either GIF or JPEG format.
All images are converted by the Liberate transcoder to a 15-bit palette, and dithered accordingly, but to optimize the quality to transfer delay ratio, images should be stored with a 256-colour palette (8-bit format).
Although TV browsers generally support imagemaps, they make the cursor very small and are almost impossible to navigate without a mouse.
5.2.8 Plug-ins
5.2.9 Audio
Size is also an issue: limit file sizes to between 500kB and 1MB. They can be clicked on to play or they can play automatically in the background of a page. Both the standard embed and bgsound HTML elements function as normal.
5.2.10 Animation
Animated GIFs work well. They should have a plain background or one that matches the background of the HTML page. Keep the file size down, as large animations slow down the loading of the page.
5.2.11 Frames
Frames should be avoided. However, they can be used to avoid having to load one section of a screen more than once, for example a menu. Too many frames can make on-screen navigation awkward so stick to standard templates and make sure that there are only links in the same frame throughout the website.
5.2.12 Forms and data entry
Not all iDTV customers will have keyboards, and entering text from a television remote control keypad is a similar operation to sending text messages from a mobile phone. HTML 3.2 form elements are supported by the Liberate and Netgem platforms. The design and use of forms should follow these guidelines:
See section 1.10.2 Data Protection Act.
See section 1.10.2 Data Protection Act
5.2.13 WebTV
WebTV was formed in 1995 and was acquired by Microsoft in 1997. It is popular in the USA and Japan. Although there are some special considerations in publishing data on this system, it basically works and renders in the same way as standard web browsers on a computer and can handle CSS, JavaScript and common audio and video formats.
Screen
One of the biggest controlling issues is the displayable screen size. This is only 420 x 560 pixels, smaller than the old standard 640 x 480 VGA resolution. When this is coupled with the requirement for larger font and graphic sizes, it becomes clear that web managers must carefully control and limit document contents.
The browser window is quite different from that usually seen on a PC screen. It is quite restricted and can render pages in a suprising way, for example, will crush a page it to make it fit.
Navigation
Internal hyperlinking navigation now becomes essential in order to reduce the amount of scrolling that any user must undertake.
Text
Only 12 characters of a page’s title will be stored in the ‘recent’ panel, but 25 characters will be stored in the bookmark section. All titling must therefore be very specific and meaningful.
Colours
The colour palette available on a television is not as large as that on a full-colour PC so images must be designed carefully. This is especially important when text is used within the graphic. The system does support all standard graphic formats such as GIF, JPEG and PNG.
Frames
A website that is organised around a frames environment will not render well on a WebTV system. All frames are automatically converted into tables, which can result in very unfriendly sites.
Version of HTML
WebTV supports the use of HTML 4.
Downloadable files
The user cannot download files when using this system. Because there is no hard disk, there is nowhere to store files such as images or PDFs.
There is a WebTV browser emulator available for computers. Using this allows a web manager to see what pages will look like when they are displayed on WebTV. The emulator can be downloaded from the WebTV website.
5.2.14 Example
The Bush Internet TV allows Internet access via a modem that connects to a telephone line and normal television viewing via a standard coaxial aerial connection. The user interface is via a remote control that contains a mouse controller and a QWERTY keyboard.
Screen resolution is quite good and the automatic text resizing carried out by the internal ANT Fresco browser assists legibility. Cascading Style Sheets are disabled but graphic rendering is standard.
Service provision is via Virgin.net and cannot be changed. Users may bookmark and go back to previously accessed pages in a very similar fashion to standard computer browser applications.
UK online interactive
In April 2002, the Office of the e-Envoy (OeE) released a 75 screen pilot service on the Sky (and ITV Digital) platforms with the intention to be on NTL and Telewest shortly. The service includes a database of UK online centres, a questionnaire, an email feedback functionality and content on current events and campaigns. OeE is now looking into the introduction of personalisation, regionalisation, transactions and forms to the service. UK online have negotiated commercial arrangements with platform providers, where there are benefits to using the UK online ‘front door’ as an access point to your iDTV service. Using the UK online portal provides benefits of a Partnership with UK online: Shared knowledge providing best practice, best price and best partnering advice. Create continuity of navigation and design to increase the user experience. Single entry point to Government information - on the Sky service they have secured a position on page 1 of the main interactive menu. UK online holds the Government’s Independent Television Commission (ITC) broadcasting license, which is essential if you wish to be on the Sky platform. You get to use an effective advertising medium at a percentage of the normal cost for advertising campaigns. For further information email sally.meecham@e-envoy.gsi.gov.uk.