RGB range test
Two ways of sending the same picture exist, and the computer and the screen have to agree on which is in use. Full range puts black at 0 and white at 255; limited range, which televisions expect, puts them at 16 and 235. When the two ends disagree the picture is either washed out or has its shadows and highlights thrown away — and no amount of adjusting brightness fixes it, because the detail never arrived. This finds which way round it is.
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Did everything stop dead at the marked line?
Running it
A dim room helps, because the whole test lives near black and near white.
Below black. Patches from 0 to 22, with a line drawn at 16. On a matching chain the steps separate gradually the whole way across. If everything left of the line is one identical black and the steps only begin after it, the link is throwing away everything below 16.
Above white. The same at the other end, with the line at 235.
Black reference. A single square of 16 on a field of 0. This one is for the opposite fault, which clips nothing and so cannot be caught by counting anything. If you cannot see the square at all, everything under 16 is being discarded. If the square is obvious and the field around it looks grey rather than black, the signal never sent a true black in the first place.
What each result means
| What you see | What it is | Where to fix it |
|---|---|---|
| Steps separate past both lines, field looks black | The two ends agree | Nothing to do |
| Flat below 16 and above 235, a hard cliff on the lines | Full range sent, limited expected | Set the graphics card to limited, or the display to full — one, not both |
| Every patch visible, field looks grey, picture flat | Limited range sent, full expected | The same two settings, the other way |
| Loss that fades in gradually and moves when you change brightness | Not this fault — it is the monitor | The contrast test covers it |
Windows
NVIDIA. Control Panel → Display → Change resolution. Below the refresh rate is Output dynamic range, with Full and Limited. There is a second one further down, Output color format; if it is set to YCbCr the range control applies to that instead, and RGB Full is what you want on a monitor.
AMD. Adrenalin → Settings → Display → Pixel Format. The entries name both parts: RGB 4:4:4 Full is what a monitor should have, RGB 4:4:4 Limited is what a television usually wants.
Intel. Graphics Command Center → Display → General → Quantization Range.
A driver update resets all three more often than it should, which is worth remembering when a screen that was correct for months is suddenly washed out.
macOS
macOS exposes no range control in its settings, and picks based on what the display reports. When it picks wrong — almost always a television or a TV-like monitor over HDMI showing raised blacks — the practical fixes are to connect over USB-C or DisplayPort instead, or to set the display’s own input to PC or Full mode so that both ends land on full range. An EDID override can force it, but that is a heavier change than most people need.
On the display
Televisions carry this setting under several names and it is always per input: HDMI Black Level (Samsung, LG), HDMI RGB Range, Super White, or simply Black Level with Low and High. Low or Limited corresponds to 16–235, Normal or Full to 0–255.
Setting the input’s icon to PC does two things at once on most sets: it selects full range and it switches off the motion and noise processing that adds delay. If a television is being used as a monitor, that is usually the single setting worth finding.
Why it is worth fixing rather than compensating
The instinct is to turn the brightness down when blacks look grey, or up when shadows disappear. Neither works, and both make things worse in a way that is easy to miss.
The detail is not dim, it is gone — discarded before the panel received it. Raising brightness on a crushed picture lifts the black that is left and still shows nothing in the shadows, because there is nothing there to show. Lowering it on a washed-out one buries the shadow detail that did arrive. Both leave you with a worse picture and a monitor whose settings now need undoing once the real cause is found.
Common questions
What are full range and limited range?
Two conventions for where black and white sit in the signal. Computers grew up on full range, using all 256 levels with black at 0 and white at 255. Television grew up on limited range, which reserves the levels below 16 and above 235 as headroom, so black is 16 and white is 235. Neither is wrong; they simply have to match at both ends of the cable. When they do not, the picture is stretched or squashed by sixteen levels at each end, and that is what you are seeing.
Why does this keep happening over HDMI?
Because HDMI began as a television standard, and graphics drivers still decide which range to send by guessing what is plugged in. A display that identifies itself as a television — which many monitors do over HDMI, and every television does — gets limited range by default. Connect the same screen over DisplayPort and it is treated as a monitor and gets full range. That is why the same panel can look right on one cable and washed out on the other, with nothing else changed.
How is this different from the contrast test?
The contrast test counts how many steps survive at each end; it measures how much of the range reaches your eye, and its answer is a number. This one asks where the loss stops. A range mismatch clips at exactly 16 and exactly 235 and nowhere else, so the cliff lands on the marked line and does not move when you change the brightness. Ordinary black crush fades out gradually and its threshold moves with every adjustment. Same symptom, different signature, different fix — one is a setting on the monitor, the other is a setting on the graphics card.
The image is washed out but nothing is missing.
That is the other mismatch, limited sent to a screen expecting full. Nothing is clipped, which is why counting patches finds nothing: instead the whole range is compressed into the middle, so black arrives as a dark grey and white as a light grey. The black reference pattern is what shows it — a field that should be as dark as the screen can go, and is not.
Should I set the graphics card or the display?
Either, and only one. Both ends have a setting, and the fix is to make them agree — changing both simply swaps a washed-out picture for a crushed one. On a computer monitor, full at both ends is the usual answer. On a television used as a monitor, it is often easier to set the display to its PC or Full mode, because that also turns off the picture processing that adds input lag.
Does this affect HDR?
HDR uses a different signalling path and its own metadata, so the range setting that matters here applies to the ordinary picture. But turning HDR on and off frequently resets the range the driver chooses, which is why a screen that was correct yesterday can be washed out today with nothing else touched. Re-check after any HDR change.