Dithering breaks banding by adding a little calibrated random noise to a gradient before quantization, so that instead of snapping to one flat value, a region's pixels scatter between two adjacent values in a ratio that averages to the right brightness. The eye blends the speckle back into a smooth ramp and never sees a hard contour - the way a painter limited to a few tins fakes a continuous wash by stippling. Dithering attacks the perception, not the root cause; it trades a visible contour for invisible noise, which the eye vastly prefers. Natural film grain and sensor noise act as a built-in dither, which is why denoising or an aggressive encode can make latent banding snap into view. The crucial catch: do not dither just before a lossy encode and expect it to survive, because compression treats the dither as noise and quantizes it back out, and the bands return. Add it as close to the final delivered bitstream as possible, or raise the bit depth instead.
The handbook · 7 volumes
Fora Soft Video Engineering Handbook
Dithering hides banding by trading visible steps for fine noise, but the encoder can strip that noise out if bitrate is tight. We wrote seven volumes covering the whole video stack, and for dithering start with Volume 1: bit depth, 8-bit and 10-bit encoding, quantization, banding and HDR. Written by Nikolay Sapunov, CEO at Fora Soft.
Adding dithering to fight banding, only to see the encoder remove it?
Share a few gradient-heavy clips: we test dithering, 10-bit encoding and encoder settings and give you the combination that keeps gradients smooth. 250+ video products shipped since 2005.
