Guidelines

Colours

Colours appear differently on TV screens and computer screens, and designers should be aware of the differences and make appropriate adjustments where necessary. A palette with a maximum of 85% (saturation) brightness should be used to avoid colour associated distortion e.g. blooming, chroma-crawl, interlace flicker, and moire patterns. Contrast between colours is an important principle to provide differentiation between background and foreground features. Very light backgrounds can create glare and can make superimposed features seem smaller and darker whereas the opposite is found with darker backgrounds.

Basic ‘rules of thumb’ are to avoid large areas of bright colours especially pure white backgrounds or pure reds or blacks, to avoid usage of heavily saturated colours, especially reds and yellows, and to try to avoid using colours with RGB values below 16 and above 236. Use colours with a maximum of 85% saturation. Care should be taken when using very bright colours or primary colours side by side especially if they have a vertical edge, and it is wise to use colours of the same hue when choosing text colours as this helps prevent vibration and colour bleed. Dot patterns and narrow contrasting lines that are tightly spaced should be avoided, and any horizontal lines should be thicker than 2 or 3 pixels in order to reduce interlace flicker.

The introduction of digital television has brought with it strong recommendations relating to receiver on-screen displays. A report by the Consumer Electronics Group to Government and the Digital UK states that it is essential to:

• Ensure that text on the screen is displayed using good colour contrast.
• Ensure that the selected menu option is indicated on screen in different colour highlight, offering good contrast, but never rely solely on colour to convey information about e.g. selected options.
• Avoid combinations of red and green.
• Avoid pure red or white colours.

Checklist for colours on TV screens

 

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