Gradient banding and contrast test: shadows, highlights and smoothness
A good screen shows a smooth greyscale ramp and separates the darkest and brightest shades. Look at the gradient, switch it to fewer steps to see what banding looks like, then pick the first patches you can tell apart.
What this test checks
A greyscale ramp from black to white should look like a smooth, even blend. When a screen cannot show enough different shades, or when it is set up poorly, you see bands, which are visible stripes where the colour jumps between steps. Switch the ramp to 64 or 32 levels to see what banding looks like, then switch back to smooth and compare. Real screens should look much closer to the smooth version.
The row of dark patches starts at pure black and brightens one level at a time. The light row starts at white and darkens one level at a time. Click the first patch in each row that you can distinguish from the background. This tells you whether the screen crushes shadows or clips highlights.
Reading your result
How to interpret the first visible patch in each row. Lower numbers are better on a good screen.
| First visible dark patch | Meaning | Typical fix |
|---|---|---|
| 1 or 2 | Excellent shadow detail | None needed |
| 3 | Good, normal for many screens | Check room light |
| 4 to 6 | Shadows are crushed | Raise brightness, lower contrast, reset picture mode |
| 7 or more | Strong crushing | Reset settings, check cable range and gamma |
Banding, bit depth and what causes it
Most screens show 256 levels of grey for each colour, called eight-bit colour. Some use dithering to simulate more, and HDR monitors use ten-bit signals. Banding appears when an image does not have enough steps between two colours for a smooth gradient, which is common in dark skies, fog and smoke in games and videos. Poor panel processing, aggressive picture modes and cable or colour format settings can make it worse.
If you see banding in the smooth ramp, reset the monitor to its default picture mode, switch off dynamic contrast and similar enhancers, and check that the graphics card sends full RGB at the correct range. Compare 8 bit and 10 bit output if your hardware supports it, and keep in mind that some banding comes from the content, not your screen.
Setting brightness and contrast
Dim the room and reset the screen to defaults. Raise brightness until the darkest patches separate from black without turning black grey, then lower contrast if the lightest patches merge with white. A good screen separates level one or two from black and the last few levels from white. Many office screens and some TVs start at level three or four.
For deeper checks, use the dead pixel test, measure your screen with the refresh rate checker and confirm your signal with the cable bandwidth calculator. For sizing and sharpness see the pixels per degree calculator.
How to use the banding and contrast test
- Dim the room and reset the monitor to its default picture mode.
- Look at the smooth gradient for stripes.
- Switch to 64 or 32 levels to see what banding looks like.
- Click the first dark patch you can see against black.
- Click the first light patch you can see against white, then adjust settings if needed.
Common mistakes to avoid
- Testing in a bright room, which hides dark detail.
- Leaving dynamic contrast on, which changes the result as you look.
- Blaming the screen for banding that is in the source video or game.
Related tools and guides
Keep going with these: Dead pixel test, Refresh rate checker, Pixels per degree calculator, monitor and GPU matcher, best graphics cards guide.
Frequently asked questions
What is colour banding?
Banding is a set of visible stripes in what should be a smooth gradient, caused by too few colour steps between shades. It is common in dark scenes and skies. Better bit depth, dithering and the right monitor settings reduce it.
How do I test my monitor for banding?
Look at the smooth greyscale ramp and check that it blends without stripes. Switch to 64 or 32 levels to see what banding looks like, then back to smooth to compare. Test in a dim room with default picture settings.
How do I set monitor brightness and contrast?
Dim the room and reset the monitor. Raise brightness until the darkest patches separate from black without grey, then lower contrast if the brightest patches merge with white. Avoid dynamic contrast, which shifts levels while you watch. Then check both ends of the ramp again.
Is 10 bit colour worth it?
It gives 1024 levels per channel against 256 in eight bit, which reduces banding in gradients, especially in HDR content. You need a 10 bit capable monitor, a suitable cable and the right output setting. Many users see little difference in everyday use.
Why do dark scenes in games look blocky?
Games often have smooth dark gradients such as smoke and fog, which show banding when there are too few levels. It can come from the game, video compression or the display. Dithering options, higher bit depth and better settings can help.
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