What causes color banding on a monitor?

First decide whether the bands are in the content

Compressed video and low-quality images may already contain tonal steps. Pause the same frame on another display, view a different gradient, or compare an uncompressed reference before changing monitor settings.

Streaming services can change quality with connection speed and device support. Banding in one dark scene does not by itself prove a display fault.

Bit depth and processing affect the number of available steps

A limited-bit-depth signal has fewer distinct values between dark and bright endpoints. Dithering can distribute neighboring values to make the transition look smoother, while poor processing can create or exaggerate boundaries.

HDR modes add tone mapping and may switch the output format or bit depth. A mismatch between content, operating-system HDR state, GPU output, and display mode can change banding without any physical change to the panel.

Use controlled browser gradients to narrow the cause

Disable temporary color filters and dynamic contrast, set browser zoom to 100%, and open the gradient and banding test. Compare grayscale with red, green, and blue gradients.

If the bands move when browser zoom, window position, HDR state, ICC profile, or GPU output settings change, the complete display pipeline deserves investigation. The pattern cannot determine native panel bit depth or certify a 10-bit path.

• Compare several gradients, not one compressed image.
• Check SDR and HDR separately.
• Restore a neutral picture mode before adjusting individual controls.
• Avoid using contrast controls to hide bands by clipping shadow or highlight detail.

Separate banding from gamut and clipping

A color that looks less saturated is not necessarily banding. Gamut describes the range of colors a system can represent, while banding describes missing smooth tonal transitions. Read sRGB vs Display P3 for the gamut distinction.

Use the black level test and white saturation test if detail disappears near the endpoints. Those pages reveal visual clipping but do not measure contrast ratio or peak luminance.