Color Banding Test: Diagnosing Bit-Depth & Dithering

In a theoretical ideal display, a black-to-white gradient transitions with microscopic smoothness across millions of shades. In reality, digital video pipelines operate in quantized steps.

Standard 8-bit color provides 256 discrete levels per RGB channel (16.7 million colors). Across a wide 3840-pixel 4K monitor, each single-step change in brightness spans multiple physical pixel columns.

If a display panel only natively supports 6-bit color (64 levels per channel) without effective spatial or temporal dithering (FRC), or if an aggressive ICC color profile crushes adjacent values together, you will observe distinct harsh lines called color banding.

In the ScreenCheck Gradient Test, we provide both continuous smooth ramps and intentional stepped ramps (8, 16, 32, 64, 128 steps).

First inspect the continuous gradient: transitions should look fluid without stark visible borders or colored rings.

Then switch between Horizontal, Vertical, and Radial gradients. If banding appears much more prominent in dark regions, the display suffers from near-black gamma quantization.

• Check GPU Output Dynamic Range: In NVIDIA Control Panel or AMD Software, ensure Output Dynamic Range is set to "Full (0–255)", not "Limited (16–235)". Limited range truncates color depth severely.

• Check Output Color Depth: Ensure your GPU is outputting 8-bit or 10-bit color (requires DisplayPort 1.4 or HDMI 2.0+ bandwidth).

• Reset Custom ICC Profiles: Over-correcting color temperature via third-party calibration software often introduces severe digital banding in the graphics card LUT.