What the no signal / smpte colour bars is
SMPTE bars are three bands. The top two thirds are seven 75% saturated bars from grey to blue. Below that a reversed strip alternates blue, black and magenta against the bars above it. The bottom band holds the -I patch, 100% white, the +Q patch, and the PLUGE strip.
PLUGE is the useful part: three patches at just below black, black, and just above black. Set brightness so the left patch is invisible and the right one is only barely distinguishable, and you have a correctly set black level. Almost every "colour bars" image online gets this strip wrong or leaves it out.
- Setting black level and brightness on a monitor or television
- A stand-in card for a stream, a broadcast or a stage screen
- Checking that a capture card or cable is passing colour correctly
No signal screen with SMPTE test card
With the box switched on, this doubles as a "no signal" screen — the message drifts slowly so it can be left running without marking a panel.
Switch the box off for a clean test card. The bar values are exact, so what you see is what the pattern is defined to be, not a JPEG of it that a compression pass has shifted.
How to run the no signal / smpte colour bars full screen
Press the fullscreen button on the player, or the F key. Escape brings you back to the page. On a desktop browser F11 does the same job and hides the browser’s own toolbars as well, which is what you want on a display that is going to be left running.
Everything you change in the settings is written into the address bar as you change it, so the version you have set up is a link. Bookmark it, or send it to whoever is running the screen. Space pauses and resumes at any time.