Color banding is the appearance of visible steps or contour lines in an area that should change smoothly in brightness or colour. Skies, fog, shadows and studio backdrops often expose it. A video chain has a finite number of numerical levels, and compression or processing can reduce the useful distinctions between neighbouring shades. The resulting boundaries may already exist in the source, or appear later during conversion and display. Banding therefore describes an observed image defect rather than identifying a single faulty component or proving that the network is too slow.
Color banding and Screen uniformity
Banding in a moving source gradient differs from fixed brightness irregularities across a panel.
Where gradients lose detail
An encoder may spend fewer bits on a quiet background than on faces or motion. Quantisation then groups similar values together. Low bit depth, aggressive noise reduction and repeated conversions can further flatten subtle differences. A higher-bit-depth output preserves more possible levels, but it cannot reliably reconstruct every gradient that a previous stage has already discarded.
Separate bands from blocks
Banding follows contours of similar tone, whereas macroblocking often produces rectangular patches tied to compression structure. Both can occur together in a dark scene. Display posterisation or an incorrect processing setting can resemble source banding, so a screenshot from one player is not enough to assign responsibility to the television, stream or decoder.
Make a controlled comparison
Pause on an affected gradient and compare the same moment using another available quality level or playback path. Keep the display picture mode consistent. If the boundaries appear at the same positions in multiple paths, the source becomes a stronger suspect. If they change with a picture enhancement setting, investigate that processing stage before adjusting network settings.
An illustrative example
A sunset shows several broad rings around the sun while faces remain detailed. Selecting a less compressed version reduces the rings. Raising the television output to 10-bit alone leaves them visible because the missing intermediate shades were lost before the image reached that output.
Practical actions
- Compare the identical gradient at two available stream qualities.
- Disable one gradient-altering picture enhancement at a time.
- Check source and output bit depth separately.