Color banding test
A good screen shows a gray gradient as smooth, while a poor panel, a low color depth setting or bad calibration shows stripes. Choose a color and the number of steps, then go full screen and look for hard edges.
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How to use it
- Pick Gray and 256 steps. Look from a normal distance in a dim room.
- Switch to Full screen and look along the strip for hard vertical edges.
- Repeat for red, green and blue.
- Pick fewer steps to see how clear banding looks, then compare it with what you saw at 256.
How it works
The strip is cut into equal bands. Band number i of n has the channel value round(i × 255 / (n − 1)). The page draws it once on a canvas, with no animation.
Worked example
With 16 steps, band 8 (counting from 0) has the value round(8 × 255 / 15) = 136, and neighbouring bands differ by 255 / 15 = 17 levels, which is easy to see. With 256 steps neighbouring bands differ by exactly 1.
Tips
- If a gradient looks banded only here, check the color depth in your graphics driver settings.
- Turn off night-light or blue-light filters while testing.
- Dark shades band more often than light ones.
Frequently asked questions
What is color banding?
Banding is visible stripes in what should be a smooth gradient. It happens when the screen, the graphics driver or the picture has too few distinct levels between two colors.
What does the step setting do?
It divides the strip into that many bands of equal width, spread from 0 to 255. With 256 each band is one 8-bit level apart. Fewer steps make the bands wider and the difference between them larger, so you can see what banding looks like.
Why do I see bands even at 256 steps?
Neighbouring 8-bit levels can be visible, especially in dark gray, on cheap panels or after a color-temperature or night-light filter. Panels with dithering hide most of it.
Which color should I check?
Gray shows overall smoothness. Red, green and blue show each channel on its own, which helps to find a weak channel or a wrong color-depth setting.
Does the full screen button change anything on the display?
No. It only makes the strip fill the screen, which makes bands easier to see. Press Escape to leave.