Color banding
Also known as: banding, posterization, gradient banding, color stepping
Color banding is the visible steps or stripes that appear in what should be a smooth gradient — often across skies, shadows, or sunsets. It happens when an image has too few tonal levels to render the transition smoothly, typically from low bit depth or heavy compression.
- Visible steps in what should be a smooth gradient
- Caused by low bit depth or heavy compression
- Reduced by higher bit depth like 10-bit color
Why gradients break into bands
A smooth gradient needs many closely spaced tones. When there are too few — as with 8-bit color's 256 levels per channel — the eye can see the jump from one tone to the next as a distinct band or stripe, an effect also called posterization.
Banding shows up most in large, gently shaded areas: a clear blue sky, a soft shadow, a backlit wall. Higher bit depth like 10-bit supplies far more intermediate tones, so the same gradient renders smoothly.
Compression makes it worse
Aggressive compression discards subtle tonal information to shrink files, which can turn a smooth gradient into visible bands even in 8-bit content that looked fine before. Re-saving an image repeatedly at high compression compounds the problem.
To avoid it, capture and edit at higher bit depth where it matters, and avoid over-compressing images and video that contain large smooth gradients.