Luminance contrast is not limited to accessible buildings and signage. Australian Government requirements for agricultural and veterinary chemical labels provide another example of measurable luminance contrast being used to improve the legibility of important information.
Luminance contrast outside the built environment
For access consultants and designers, luminance contrast is most commonly associated with the built environment. It appears in requirements for elements such as signage, doorways, sanitary facilities and tactile indicators.
The same visual principle has applications elsewhere.
The Australian Pesticides and Veterinary Medicines Authority (APVMA) regulates agricultural and veterinary chemical products in Australia. Its Agricultural Labelling Code includes requirements covering the presentation and layout of product labels, including print size, typeface, print quality and colour.
Section 3.5, Colour, sets a specific luminance contrast requirement.
There must be a luminance contrast of at least 30% between letters and background.
This is a measurable requirement, not a general instruction to select colours that appear sufficiently different.
Colour difference and luminance difference are not the same thing
The APVMA requires printed letters to contrast distinctly with the background. It directs the use of light-coloured text against a dark background and dark text against a light background.
It also recommends well-contrasted colours with widely differing hues and an appreciable difference in value, while advising against strongly saturated colour pairs for the text and background.
There is a useful distinction here.
Two colours can be obviously different in hue but still have relatively similar luminance. For example, a designer looking at a bright red beside a bright green may see two very different colours. That does not necessarily mean the combination provides a strong luminance difference or good legibility for every reader.
This is one reason colour selection alone should not be relied upon where a measurable luminance contrast requirement applies.
The background can undermine otherwise legible text
The APVMA also addresses a problem that regularly occurs in graphic design: placing text directly over photographs, illustrations or multi-coloured backgrounds.
A photograph may be dark behind one part of a word and considerably lighter behind another. Even where the lettering itself does not change, the effective contrast can vary across the text.
The APVMA advises that text printed directly over pictorial or multi-coloured backgrounds may be difficult to read and should be avoided. It suggests placing a plain background, preferably white, beneath the lettering to improve legibility.
That is a practical detail with much wider application.
The same issue can occur with building signage, directories, maps, control panels and wayfinding information. A visually interesting background may work well as a graphic treatment but perform poorly once important information is placed over it.
Where information needs to be read quickly and reliably, a simple background often provides much greater control.
Colour blindness is specifically considered
The APVMA requirements also recognise that colour combinations can affect people differently.
Its guidance identifies combinations involving green, yellow, orange and red as potentially problematic for people with colour blindness. In particular, avoid red lettering on a green background, or green lettering on a red background.
The guidance also advises against placing red, green, brown, grey and purple immediately adjacent to, or on top of, one another.
This reinforces a useful design principle: colour should not be the only visual characteristic separating important information from its surroundings.
A 30% requirement from another Australian regulatory setting
For building professionals, the APVMA requirement is noteworthy because it shows an Australian Government regulatory authority using a 30% minimum luminance contrast requirement outside the building accessibility framework.
Its regulatory purpose differs from AS 1428.1, and the APVMA requirement should not be treated as creating or modifying a building accessibility requirement.
The comparison is nevertheless useful.
In both settings, the issue is not simply whether two colours have different names or look different on a drawing. What matters is whether the relevant elements are sufficiently visually separated.
This becomes particularly relevant when specifications rely heavily on nominated colours.
A drawing might identify “white text on blue”, for example, but that description alone does not establish a specific luminance contrast percentage. The final result depends on the actual characteristics of the selected colours or materials.
The same problem can arise when products are substituted. A replacement colour may look broadly similar to the originally specified product while producing a different luminance relationship.
Rendering cannot demonstrate compliance
Computer screens can also create false confidence.
Brightness, display calibration, viewing conditions, and how software renders colours can all influence how strongly two colours appear to contrast. Printed documents introduce another set of variables.
A graphic that appears clear on a designer’s monitor does not, by itself, demonstrate that a nominated luminance contrast has been achieved.
Where the applicable requirement sets a measurable threshold, the documentation should identify that requirement rather than relying solely on colour rendering to communicate design intent.
The APVMA’s 30% requirement is a good example. The regulatory instruction is measurable: at least 30% luminance contrast between the letters and their background.
A useful reminder for designers
The APVMA labelling requirements show how luminance contrast can be a practical tool for improving the legibility of important information.
They also reinforce several principles that extend beyond product labels: don’t assume different colours automatically provide good contrast; avoid unnecessarily complicated backgrounds behind important text; consider users with colour vision deficiencies; and distinguish between visual appearance and measurable luminance contrast.
For access consultants and building designers, it is another Australian example of a familiar principle being applied in a very different regulatory environment.
Sometimes the simplest question is also the most useful one: does the information actually stand out from what is behind it?
Please contact LumiLab to discuss your accessibility needs. Visit our website to learn more or call us on 1300 142 841.
Disclaimer: This publication provides general information only and does not constitute legal, certification or project-specific advice. Requirements may vary between projects and change over time. Always verify the current NCC, legislation and applicable Australian Standards, and obtain project-specific advice where required.
LumiLab guides, webpages, and articles discussing luminance contrast, accessibility, or optometry and ophthalmology are intended only for educational and informational purposes and do not constitute medical or professional advice. The information presented, including but not limited to text, graphics, images, and other material, is for informational purposes and is not intended to be a substitute for professional advice, medical diagnosis, or treatment. Always consult your physician, optician, or other health care professional if you have questions about your eye health or vision.
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Reference: Australian Pesticides and Veterinary Medicines Authority (APVMA), Label presentation and layout, Section 3.5 – Colour, Australian Labelling Code.