Monitor Color Test — Gradient & Banding Check
This monitor color test shows in one screen whether your display renders gradients smoothly or breaks them into visible steps. Full-width greyscale and RGB ramps sweep every level your panel can produce, so banding, posterisation and dithering noise become obvious. Run it fullscreen in a dark room and within a minute you will know whether the problem is the panel, the signal chain or the content you were watching.
How to run the monitor color test
Go fullscreen, dim the room and sit at your normal viewing distance. Banding is a contrast effect, so ambient light hides it and a dark room exposes it. Sweep your eyes slowly across each ramp rather than staring at one spot: human vision exaggerates edges, which is what turns a single-level step into a hard line.
Check the greyscale ramp first, then red, green and blue on their own. A screen that bands in only one channel usually has a broken lookup table or an aggressive colour profile rather than a bad panel. Then judge the darkest tenth of the ramp: that is where nearly every display fails.
What colour banding actually is
Banding appears when a gradient has fewer shades available than the distance it has to cover. A 1440-pixel-wide black-to-white ramp on an 8-bit screen has only 256 grey levels, so each level stretches across five or six pixels. Where two levels meet you get a visible edge, and a run of those edges reads as stripes.
The arithmetic is blunt: 6 bits per channel gives 64 steps, 8 bits gives 256, 10 bits gives 1024. Moving from 8-bit to 10-bit does not add colours you have never seen before; it adds three extra shades between every pair of shades you already had. That in-between detail is the only thing a smooth gradient needs.
6-bit, 8-bit and 10-bit panels, and what FRC hides
Most inexpensive fast-refresh panels are not truly 8-bit. They are 6-bit panels running frame rate control, which flickers each pixel between two neighbouring shades quickly enough that your eye averages them into the shade in between. Spec sheets call this 8-bit (6-bit + FRC) or quote 16.2 million colours instead of 16.7 million; the same trick one level up produces “10-bit” monitors that are really 8-bit + FRC.
FRC works well, but it is temporal rather than spatial: it spends time to buy precision. On a large dark gradient you may see fine shimmer or crawling noise instead of a clean band, and it worsens at lower refresh rates, where there are fewer frames to average across. Windows reports the link as 8-bit either way, so the operating system cannot tell you what the panel really is — only the manufacturer's colour-count line can.
Why banding always shows up in dark scenes
Shadows are where bit depth runs out first. Human vision is roughly logarithmic, so the perceived gap between levels 2 and 3 is large while the gap between 200 and 201 is invisible. The sRGB gamma curve compensates by spending more code values on the dark end, but it cannot create levels that do not exist: below about level 20, an 8-bit signal has nothing left to give.
That is why a night sky or a torch beam on a wall bands while a bright blue sky often does not, and why raising brightness or flattening gamma makes it worse. If your dark ramp bands badly while the mid-tones stay clean, check your tone curve with the gamma test before you blame the panel.
Is it the monitor, the GPU, the cable or the content?
Work through them in this order — three of the four cost nothing to rule out.
Content first. Compressed video and 8-bit JPEGs arrive with banding already baked in. If a streamed sunset bands but the ramps on this page are clean, there is nothing wrong with your hardware.
Then the GPU output. Limited-range RGB (16–235) fed to a full-range panel is the most common cause of banding that appears suddenly after a driver update or a cable swap. Set the output to RGB, Full dynamic range, 4:4:4 chroma, at 8 bpc or higher.
Then colour management. A stale or auto-loading ICC profile applies a lookup table that quantises an already 8-bit signal a second time. Removing the profile and rebooting resolves a surprising share of “my new graphics card causes banding” reports.
The cable last. A digital cable either carries the signal or fails visibly, with sparkles, dropouts or a black screen; it does not gently degrade colour. What it can do is force a fallback: if the link cannot carry your resolution, refresh rate and bit depth at once, the GPU drops to 4:2:2 chroma or 8-bit, and that looks like banding. Banding that appears on DisplayPort at 144 Hz but disappears on HDMI at 75 Hz is a bandwidth story, not a cable-quality story.
If the stripes stay fixed in one region of the screen instead of following the gradient, they are not banding at all. That is panel non-uniformity, and the screen uniformity test is the tool for it.
Bit depth versus bandwidth on the cable
Bit depth is not free. A display link carries pixels multiplied by refresh rate multiplied by bits per pixel, so asking for 10-bit instead of 8-bit raises the bandwidth requirement by about 25%. That is why a GPU offers 10 bpc at 120 Hz but only 8 bpc at 165 Hz on the same monitor, and why 4K60 in 10-bit 4:4:4 exceeds what HDMI 2.0 can deliver.
When you hit that ceiling, something has to give: refresh rate, chroma resolution or bit depth. For desktop work and SDR gaming, 8-bit full-range RGB at the higher refresh rate is usually the better trade, because games, the desktop and almost all SDR content are 8-bit anyway. The extra depth earns its bandwidth only with genuinely 10-bit material: HDR video and colour-graded work.
What this test cannot tell you
A browser cannot read your panel's true bit depth. It only draws values and lets you judge the result, and everything between the CSS colour and the glass — compositor, GPU lookup table, ICC profile, the monitor's own processing — can alter what arrives. This monitor color test therefore shows what your whole signal chain produces, not what the panel is capable of in isolation.
It also cannot separate well-implemented FRC from native 8-bit by eye except at the shadow end, and it says nothing about colour accuracy: a screen can draw perfectly smooth ramps and still be badly off-white. For the remaining panel checks, start from the monitor test hub.
Frequently asked questions
Why does my OLED monitor have color banding?
Almost always the content and near-black handling, not a defect. OLED reaches true black, so the first few grey levels above it are exactly where an 8-bit source runs out of steps — an LCD hides the same shortfall under backlight glow. Add near-black processing and brightness limiting that shifts levels as the image moves, and you get shadow outlines. Check whether the same clip bands on a second display before returning the monitor.
Is gradient or color banding the result of a bad monitor or a bad graphics card?
Usually neither — it is the content or the output settings between them. A genuine hardware fault shows up as dead pixels, flicker or sparkles, not as clean, evenly spaced stripes. Judge it with a live gradient rather than a compressed image: if the live ramp is smooth, your chain is fine. If it bands, set the GPU to RGB, Full range, 4:4:4 and remove any ICC profile before suspecting the panel.
How do I know if my monitor is 8-bit or 6-bit + FRC?
Check the spec sheet, not Windows. Windows reports the link as 8-bit whether the panel is native 8-bit or 6-bit + FRC, so the operating system cannot answer this. Manufacturers give it away in the colour line: 16.7 million colours means true 8-bit, 16.2 million means 6-bit + FRC. Visually, look at the darkest part of a greyscale ramp — FRC panels show fine shimmer or crawling noise there rather than clean steps.
I get color banding with DisplayPort but not with HDMI — is the cable bad?
The cable is almost never the cause. Digital links fail loudly — sparkles, dropouts, no signal at all — they do not gently soften colour. What differs between the two ports is the mode that was negotiated: one may be running limited-range RGB or 4:2:2 chroma, and both look exactly like banding. Compare the colour format, dynamic range and bit depth reported for each input in your GPU control panel before buying another cable.
How do I test if 10 bit color depth works?
Show a 10-bit gradient and look at the shadows — the extra 768 steps only reveal themselves there. Set your GPU output to 10 bpc, then compare an 8-bit ramp and a 10-bit ramp side by side; if they look identical, something in the chain is still 8-bit. Remember that the Windows desktop and most applications render in 8-bit regardless, so a smooth desktop gradient proves dithering, not a true 10-bit path.
8-bit at 165Hz or 10-bit at 120Hz — which gives better color?
Take 8-bit at 165 Hz for everyday use and gaming. A display link has a fixed bandwidth budget and 10 bits costs roughly 25% more of it than 8 bits, which is why the higher refresh rate disappears when you switch. Games, the desktop and nearly all SDR content are 8-bit anyway, so the extra depth sits idle. Choose 10-bit only for HDR video or colour-graded work, where the source really carries it.
Bad color banding with an RTX 3060 — any fix or solution to this?
Remove your ICC profiles first. A stale or auto-loading colour profile re-quantises an already 8-bit signal and is the usual cause of banding that appears without any hardware change. Open Color Management, tick “Use my settings for this device”, remove every listed profile and reboot. If it survives that, set Output dynamic range to Full and Output color format to RGB in the NVIDIA control panel, and disable the Calibration Loader task.