Skin-tone representation

Overview

In most products, the range of people shown in the imagery is an inclusivity question: important, but a matter of who feels welcome. In a health product it is also a correctness question, and that is why this page exists as a requirement rather than as advice.

The mechanism is straightforward. A great many clinical signs are described, and illustrated, by how they change the appearance of skin. Redness is the obvious one: inflammation, rashes, allergic reactions, cellulitis, sunburn. On pale skin those present as red. On brown and black skin they frequently do not. The same conditions may present as purple, grey, darker brown, or as a change in texture or warmth with little visible colour change at all.

So an image set that shows a condition on one skin tone is not merely under-representative. For every reader whose skin is a different tone, it is wrong: it shows them something that does not look like what they would see, and they may reasonably conclude they do not have it.

How it works

The requirement, stated so it can be checked:

1. Any image set showing people covers a genuine range of skin tones, not two points at the extremes. A set of six figures in which five are pale and one is not has met a quota and not the requirement.
2. Any set showing a clinical sign covers the range for that sign, or it does not ship. This is the correctness half, and it is stricter: a single illustration of a rash is worse than no illustration, because it is confidently wrong for most of the world's readers.
3. Skin tone is not correlated with role across the set. If the figures demonstrating good technique are pale and the ones demonstrating errors are not, the set is making a statement whether or not anyone intended it. Check the set as a whole; individual images cannot reveal this.
4. Interface colour is not derived from skin tone. A product must never use a reader's skin tone to select a theme, a category colour or anything else.

A tone scale is a tool, not the requirement. Recording which tones a set covers against a published dermatological scale is what makes coverage checkable and gaps visible, and it is the practical way to run point 2. It does not by itself satisfy anything: a set can cover a scale evenly and still fail point 3.

Illustration and photography have different obligations. An illustrated set can be produced across tones from the same drawing, which makes coverage cheap and therefore inexcusable to skip. A photographic set cannot, which is a real cost and one of the stronger reasons to illustrate rather than photograph. See Illustration style.

Avatars are a separate problem and are covered on Avatars and identity. A default avatar with a skin tone assigns one to everybody who has not chosen.

Using it

Audit the set, not the image. Representation is a property of the collection. Lay every image out together and ask three questions: what range is covered, is tone correlated with role or with outcome, and which reader would find nobody here.

Describe what to look for, not only the colour. Text is where this is actually solved. "Warm, swollen and tender, and darker or more purple than the skin around it" works across tones in a way that "red" does not.

Do not let a default become a norm. Where one image has to stand for a concept, rotating a default is not a solution and neither is picking a mid-tone as a compromise. Either the concept needs several images or it does not need one.

Commission for coverage from the start. Retrofitting range into an illustration set means re-drawing it. Putting the requirement in the brief costs nothing; discovering it after delivery costs the set.

Do not ask readers to self-identify a skin tone to get correct information. Where the product genuinely needs it because it is showing a clinical comparison, the tone is asked for once, explained, optional and revocable, and it is health data subject to consent and disclosure.

Tokens

There are no skin-tone tokens and there will not be. Skin tone is content, and tokenising it would put a fixed palette of human beings in a stylesheet. Interface colour and depicted skin tone are unrelated systems and must stay that way.

Accessibility impact

• This is an accessibility failure in the plain sense, not only an equity one: information present for one group of readers is absent for another, and the absent group cannot tell that anything is missing.
• Text alternatives carry more weight here than anywhere else. A description that says what to look for reaches every reader, including those using a screen reader and those whose skin the image does not depict. The signs that are not colour changes are part of what that description says. See Alt text and descriptions.
• Never rely on colour change alone to describe a sign. This is principle 2 from Principles in an unexpected place: colour is an unreliable channel here for a reason that has nothing to do with the display.
• Clinical imagery needs a warning and an explicit control to reveal, across every tone, for the reasons on Photography.
• Coverage should be recorded and published, so that a gap is a known gap rather than an unexamined one. This is the same posture as the accessibility statement.

Related

• Illustration style explains why illustration makes coverage affordable, and what to put in the brief.
• Inclusive content is the wording side of the same requirement.
• Body diagrams is where representation and clinical accuracy meet most directly.