Each channel is stored as a fixed number of bits, and the bit count sets a hard ceiling on how many steps are available between pure black and full brightness. Eight bits allow 256 of them; ten bits allow 1,024, four times as many gradations across the same range. A smooth gradient — a sky, a soft studio backdrop, a gradient generated as a background — needs enough of those steps to pass as continuous rather than as a staircase.
Banding is what happens when it runs out of steps, and it is not caused by bit depth alone: a generation's own sampling already quantises a long, low-frequency ramp into a limited set of values, and lossy compression spends its budget on edges and texture rather than a ramp nobody was expected to notice, discarding more of the steps that were left. The result can look fine at rest and posterise the moment a grade stretches contrast across it — the steps were always there, a grade just spread them far enough apart to see.
This is a genuinely separate axis from both resolution and chroma subsampling. Resolution is pixel count; bit depth is how many brightness values each pixel can hold regardless of how many pixels there are. A file can be sharp, high-resolution and still band visibly, because sharpness and gradation depth were never the same property.
In practice
- Banding in a smooth gradient is a bit-depth-and-compression symptom, not a resolution one — more pixels will not fix visible steps in a sky.
- Grading — pushing contrast, lifting shadows — makes existing banding worse by spreading fewer levels across a wider range.
- Work in a higher-bit-depth intermediate and dither on the way down to delivery if the source is due for a grade; convert down for the final export last.
The mistake to avoid
Upscaling or raising the resolution setting to fix banding. Banding is a shortage of brightness levels, not a shortage of pixels, and neither upscaling nor a sharper resolution adds a single new level to the gradient.
Go deeper
Stop Banding After You Grade AI Skies
Generated skies posterize under contrast. Use a 10-bit intermediate, dither, and a stills-plus-motion checklist before you add grain or reroll.
Related terms
Codec
A codec is the scheme that compresses video or audio down to a storable size, and it is a different thing from a container format like MP4 or MOV, which is only the wrapper the codec's data travels inside.
Chroma subsampling
Chroma subsampling is how much colour detail a codec keeps relative to brightness detail, written as a three-number ratio like 4:2:0 or 4:4:4 — a separate axis from resolution, so a sharp, high-resolution file can still carry far less colour information than its pixel count implies.
Upscaling
Upscaling raises the resolution of media you already have, inventing plausible detail rather than recovering detail that was never recorded.
Resolution
Resolution is how many pixels an output contains, usually named by its height — 720p, 1080p, 4K — and set before generation rather than after.
Temporal consistency
Temporal consistency is how well a generated clip keeps things the same from one frame to the next — a shirt that stays the same colour, a background that stays put.
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