Borrow from the web's own rules

There's no single accessibility standard written for digital signage, but the Web Content Accessibility Guidelines (WCAG 2.2) published by the W3C cover most of what a screen shows: text, colour, images, video and motion. They're a sensible yardstick, and several of the tips below come straight from them.

Contrast first

Low contrast is the most common reason screen text is hard to read, and a screen in a bright room makes it worse. WCAG 2.2 asks for a contrast ratio of at least 4.5:1 for normal text and at least 3:1 for large text, which it defines as 18 point, or 14 point bold.

  • Check your colours with any free contrast checker before you design a whole set of slides.
  • Light text on a dark background usually reads well on screens and glares less in dim rooms.
  • Never put text straight over a busy photo. Add a solid or darkened panel behind it.
  • Brand colours that pass on paper can fail on a screen near a window; test them where they'll hang.

Text size and fonts

Text that's comfortable on your laptop is almost always too small on a wall. Size it for the furthest person who needs to read it, and check by standing there.

  • Use a plain, sturdy font. Thin, condensed and decorative fonts fall apart at a distance.
  • Prefer sentence case. Long lines in capitals are slower to read.
  • Keep lines short and give them room to breathe.
  • Fewer words, larger: one headline and a short line usually beat a paragraph.

Don't rely on colour alone

WCAG asks that colour isn't the only way information is shown. On a screen that means a red price for "sale" or a green dot for "open" also needs a word, an icon or a shape. Many people can't tell certain colours apart, and in strong light nobody can.

  • Write "Sale" or show the old price crossed out, not just a red number.
  • Pair status colours with words: "Open", "Closed", "Delayed".
  • In charts and timetables, use labels as well as colours.

Time to read, and no flashing

A slide that changes before someone finishes reading it is as good as invisible to slow readers, people reading in a second language and anyone who looked up halfway through. Read each item aloud at a calm pace, add a few seconds, and use that as its duration.

Motion should help, not distract. WCAG's rule on flashing is clear: content shouldn't flash more than three times in any one-second period, because rapid flashing can trigger seizures in people with photosensitive epilepsy. Avoid strobing transitions and fast-blinking text altogether.

Video without sound

Most signage plays with the sound off, so a video that depends on someone speaking says nothing to the room. That's also true for people who are deaf or hard of hearing.

  • Burn captions into videos that include speech.
  • Choose videos that make sense without sound: show the product, the dish, the result.
  • Put the key message in text on screen, not only in the voice-over.

Plain language and more than one language

Short, everyday words help everyone, and especially people reading in a language that isn't their first. In tourist areas, hospitals, transport and public buildings, consider a second language.

  • Say one thing per slide.
  • Use familiar icons with a word beside them: an icon alone can be read in different ways.
  • If you show two languages, give them equal weight, or alternate whole slides rather than cramming both onto one.

Placement

Where the screen hangs decides who can read it. A board high above a counter may be fine for people standing in a queue but hard to read for someone using a wheelchair or for a child.

  • Put information people need up close, such as wayfinding, opening hours or a door screen, at a height that can be read seated as well as standing.
  • Keep the path in front of the screen clear, so people can stop and read without blocking a corridor.
  • Avoid spots where glare from windows or lights hides part of the screen at some times of day.

QR codes with a fallback

A QR code is handy, but not everyone can or wants to scan one. Put a short web address beside it, keep the code large enough to scan from where people stand, and leave it on screen long enough to be scanned.

None of this needs special equipment, just a few habits when you make content. With Jonza, text, prices and opening hours are live layers rather than baked into images, so you can make them larger or clearer without redrawing a whole slide. If you'd like a second pair of eyes on your screens, we're happy to help.