Gradient & Colour Banding Test
Look for visible bands or edges where the gradient should blend evenly. Move back from the screen — banding is often clearer at a distance.
Colour banding is visible stepping in what should be a smooth gradient, caused by the display or the signal not carrying enough distinct levels to render a continuous transition. It shows as distinct bands rather than an even blend.
How to use this test
- Start with the greyscale gradient and look for vertical bands rather than an even blend.
- Switch to dark greys — banding is usually worst in shadow detail, where the steps between levels are proportionally largest.
- Compare against the stepped reference, which is deliberately banded into 16 blocks. That is what obvious banding looks like.
- Step back a metre or two. Banding is often easier to see at a distance than up close.
What your results mean
| What you see | What it means |
|---|---|
| A smooth blend with no visible edges | Your display and signal chain are rendering the gradient well. |
| Faint bands in the darkest quarter only | Common and generally normal. Shadow detail is where limited bit depth shows first. |
| Clear bands across the whole gradient | Either a lower bit depth panel, or a display setting reducing the levels available — check colour depth and any bandwidth-saving options. |
| Bands in one colour but not others | A per-channel limitation, sometimes caused by a signal format that subsamples colour rather than by the panel itself. |
Common problems and fixes
Banding appeared after changing a cable or resolution
A signal running short of bandwidth may drop to a lower colour depth or a subsampled format to fit. Try a cable rated for your resolution and refresh rate combination.
Banding is worse after enabling a high refresh rate
Same cause. At the top of a link's bandwidth, colour depth is usually what gets reduced first. Lowering refresh rate slightly often restores full depth.
Your panel is advertised as 10-bit but bands visibly
Many displays marketed as 10-bit are 8-bit panels using dithering to approximate it. That is a legitimate technique, but the result can still band where true 10-bit would not.
Banding only appears in one application
Then it is the content or that application's rendering rather than the display. Compressed video in particular bands in gradients regardless of panel quality.
Why this matters
Banding is the fault people notice without being able to name — skies that look like contour maps, shadows that step instead of fade. Because it is often caused by a cable or a display setting rather than the panel, it is frequently fixable for free. Confirming whether your screen bands, and where, tells you whether to change a setting or stop blaming the monitor.
Longer walkthrough: Gradient & Banding Test — full guide.
Frequently Asked Questions
What causes colour banding?
A limited number of distinct levels somewhere in the chain. It can be the panel's bit depth, a signal format reduced to fit the available bandwidth, a display setting, or compression in the content itself. The gradient cannot be drawn smoothly if the levels to draw it with do not exist.
Is some banding normal?
Faint banding in the darkest part of a gradient is common and not usually a defect, because shadow steps are proportionally the largest. Obvious banding across the whole gradient points to a setting, a cable or a genuinely limited panel.
Does a 10-bit panel eliminate banding?
It reduces it substantially, but many displays sold as 10-bit are 8-bit panels using dithering to simulate the extra levels. That works well, though it does not always match a true 10-bit panel, and content and cable bandwidth still matter.
Why did banding appear after I changed a setting?
Most often a bandwidth trade. When a link cannot carry your resolution, refresh rate and full colour depth at once, colour depth is usually what gets reduced — so raising refresh rate can introduce banding.
Can banding be fixed?
Often, yes. Check that your cable is rated for your resolution and refresh rate, confirm the colour depth setting in your graphics control panel, and check for any bandwidth-saving option in the monitor's menu. If the panel itself is the limit, it cannot be fixed in software.
Is banding the same as posterisation?
They describe the same visual result — smooth tones reduced to visible steps. Posterisation more often refers to the effect in the source content, and banding to the effect introduced by the display chain.
Sources: MDN — Fullscreen API
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