Colour Depth Test.
Run the dark-zoom ramps and split the near-value pairs to see how many levels your panel actually resolves — 6-bit, 8-bit or 10-bit, with or without FRC dithering.
Near-value shade pairs
Each tile is split down the middle into two almost-identical dark greys. If you can see the seam, your panel resolves that step; if a tile looks like one flat shade, those two levels have merged. In a dimmed room, find the smallest pair you can still split — that's roughly the finest step your display and current settings resolve near black.
Δ is the gap in 8-bit levels. A true 8-bit panel separates every pair here; a 6-bit panel loses the tightest ones. Raise brightness or drop any "black boost" / dynamic-contrast mode if the smallest pairs vanish entirely.
Bit-depth reference
What each depth means in levels and total colours, and where you'll find it. "+ FRC" panels dither two levels to fake a higher depth — convincing in motion, sometimes shimmery on static dark gradients.
| Depth | Levels / channel | Total colours | Typical use |
|---|---|---|---|
| 6-bit | 64 | 262 K | Budget TN / VA |
| 6-bit + FRC | 64 → ~256 | ~16.7 M | Budget "8-bit" panels |
| 8-bit | 256 | 16.7 M | Mainstream standard |
| 8-bit + FRC | 256 → ~1024 | ~1.07 B | "10-bit" monitors |
| 10-bit | 1,024 | 1.07 B | HDR / pro work |
Remember the whole chain has to agree: a 10-bit panel only outputs 10-bit if the GPU, cable, OS setting and app all do too. That's why the browser's colorDepth reads 8-bit here even on capable hardware — the visual ramps and pairs above are the more honest measure.
How the colour-depth test works
Bit depth sets how finely a display can slice the range from black to white. Too few slices and adjacent shades collapse together — you get banding in gradients and lost detail in shadows. Because the steps between levels are largest, relatively, near black, that's where a low-bit panel gives itself away first. This test aims straight there.
- 1. Run the dark-zoom ramps. They stretch just the darkest levels across the whole screen, so a missing level shows as a hard step instead of a smooth fade.
- 2. Split the near-value pairs. Work down to the tightest pair you can still tell apart — that's your effective resolution near black.
- 3. Compare against the reference. Match what you see to the bit-depth table to place your panel at 6-, 8- or 10-bit, ± FRC.
- 4. Rule out the pipeline. Set the highest output depth and a neutral profile, disable vivid/dynamic modes, then re-judge the hardware.
What your results mean
Match what you see on the dark ramps and near-value pairs against the rows below to find your panel's real effective bit depth, not just what the spec sheet claims.
| What you see | What it means | What to do |
|---|---|---|
| You can split even the tightest near-value pairs (Δ1–2), and every dark ramp fades smoothly with no visible steps | True 8-bit (or better) per channel — no meaningful banding | Nothing to do. |
| The smallest near-value pairs merge into one flat shade, and the dark ramps show hard steps instead of a fade | Effective bit depth is lower than advertised — likely 6-bit, or 8-bit crushed by a picture mode | Set the OS/GPU output to its highest bit depth and turn off any dynamic-contrast / vivid mode, then re-test. |
| The ramps look mostly smooth, but static dark areas show a faint shimmer or dither noise | FRC dithering — the panel is faking extra levels by flickering between two shades | Expected on a "6-bit+FRC" or "8-bit+FRC" panel; not a fault, just not native bit depth. |
| One colour's dark ramp (red, green or blue) bands noticeably more than the other two | That channel individually has lower effective depth or gain | Confirm on the same channel's ramp in the RGB channel test. |
| "Your display" reports 24-bit even though the monitor is marketed as 10-bit | Normal — browsers report the 8-bit browsing context, not the panel's real depth | Ignore that readout; trust the dark ramps and near-value pairs, and confirm the GPU, cable and OS are all set to a 10-bit path outside the browser. |
Frequently asked questions
What is monitor colour depth (bit depth)?
Colour depth is how many distinct levels of brightness a display can show per colour channel. 8-bit means 256 levels each of red, green and blue — about 16.7 million colours; 10-bit means 1,024 levels each — over a billion. More levels means smoother gradients and finer shadow detail. This test probes how many levels your panel and current settings can actually resolve, which is often less than the spec sheet claims.
How do I tell if my monitor is really 8-bit or 10-bit?
Run the near-value pairs on this page: each tile shows two adjacent dark shades side by side. On a true 8-bit (or 10-bit) panel you can tell apart even the closest pairs; on a 6-bit panel the smallest pairs collapse into one flat shade. Then check the "Your display" readout — but note browsers almost always report 24-bit (8-bit per channel) even on 10-bit panels, so the visual pairs and the dark ramps are the more honest test.
Why does my browser report 24-bit colour depth on a 10-bit monitor?
The screen.colorDepth value the browser exposes is the colour depth of the browsing context, which is 24-bit (8 bits per channel) in almost every browser regardless of the panel. True 10-bit output depends on your GPU driver, the cable, the OS setting and the app all being in a 10-bit pipeline. So a 24-bit reading here does not mean your monitor is only 8-bit — it means the browser is drawing in 8-bit.
What is FRC and why does an "8-bit" panel still band?
FRC (Frame Rate Control) is dithering: the panel rapidly flickers a pixel between two levels so your eye averages them into an in-between shade, faking extra levels. A "6-bit + FRC" panel is marketed as 8-bit and an "8-bit + FRC" as 10-bit. FRC is convincing in motion but can still show faint banding or a subtle shimmer on static dark gradients — which is exactly what the zoomed dark ramps here expose.
How is this different from the gradient / banding test?
The gradient test uses full-range ramps to spot whether banding exists at all. This colour-depth test zooms into the dark end — where too-few levels break down first — and adds the near-value pairs and a bit-depth reference so you can pin down the effective depth (6-bit vs 8-bit vs 10-bit, with or without FRC) rather than just noticing a band. Use the gradient test to see banding; use this one to explain it.
Does the "Your display" readout ever show a true 10-bit depth?
Rarely, and only when the whole pipeline is in a 10-bit path — a 10-bit-capable GPU output, a display connected and set to 10-bit, and a browser/OS combination that reports it faithfully. Most consumer setups report 24-bit regardless. Treat the readout as a sanity check, not proof either way — the dark ramps and near-value pairs above are the more reliable, hands-on measure of what your eyes can actually resolve.