Why Your LED Wall Looks Different from Your Monitor

Everyone who designs for LED has had this moment: the subtle gradient you loved has turned to bands, the deep navy has gone purple, and the white is painful. Nothing's wrong with the wall. It's just a very different kind of display from your monitor.

Brightness is measured in nits

A nit is one candela per square metre. Daktronics' guide to LED displays says a display needs at least 5,000 nits to be visible in daylight. For comparison, VESA's DisplayHDR 400 tier for monitors asks for 400 on a small patch, and 320 sustained.

So a wall can be far brighter than the monitor you designed on, and indoors it'll usually be turned well down from its maximum. Turning it down has its own effects, as dark tones may lose detail. Ask the operator what brightness they'll run at, and judge your work at that level.

Dark isn't the same on the wall

Your monitor is judged in a dim studio. A stage is lit for cameras, and a stand is lit for a hall. Light falling on the wall lifts the blacks, so detail in the shadows disappears and low-contrast type vanishes.

Design with stronger separations than feel natural at your desk. Keep a darkest tone you can live with being lifted, and don't put anything important in it.

Know which colour space you're in

Most show content is still made for ITU-R BT.709, the HDTV standard, with a D65 white. LED processors can map that to their own panels in different ways, and an uncalibrated wall may be noticeably more saturated than the standard. Before colour-critical brand work, ask how the wall is calibrated, and bring a reference of the brand colour to compare by eye.

HDR is a further step. BT.2390 describes a curve that covers 10,000 down to less than 0.001 candelas per square metre. That's a different production chain from start to finish, so only choose it deliberately, and only if the whole chain supports it.

Watch your gradients

Big, slow gradients are the classic failure. On a wall they stretch across many metres, and banding that was invisible on your screen becomes obvious. Adding a little noise helps, as does a higher bit-depth codec such as NotchLC, if your server supports it.

Test on the wall

There's no substitute for it. Send a test file with your brand colours, your darkest gradient, your smallest type and pure white, and look at it from where the audience will sit. If you can't get on the wall before the day, leave time for colour changes at rehearsal.

More on this kind of work is on our conference content page.