Color Banding Color Banding (Posterization)

What color banding is

Color banding is the visible stepping in a smooth gradient. A sunset, a fog bank, or a fade to black should change shade continuously, but a banded image shows flat stripes with hard edges between them. RTINGS notes that the effect is also known as posterization, that it can appear in any scene with color gradients, and that it matters most for HDR content because HDR uses a wider range of colors and carries more color depth.

The cause is always the same: the system has fewer distinct levels than the gradient needs, so nearby shades get rounded to one value. RTINGS lists three places it can start. The signal may not carry enough bits to separate similar colors, the screen's bit depth may be too low to follow a high-bit signal, or the TV's own processing may introduce the banding.

How bit depth sets the step size

Bit depth is the number of levels each of the red, green, and blue channels can take. Fora Soft's explainer puts 8-bit at 256 levels per channel, 10-bit at 1,024, and 12-bit at 4,096. RTINGS expresses the same gap as totals: 16.7 million colors at 8-bit against 1.07 billion at 10-bit. ITU-R BT.2100, the HDR television recommendation (current edition BT.2100-3, approved February 2025), specifies a bit depth of either 10 or 12 bits per sample, which is why HDR10 is a 10-bit format. The full explainer on bit depth is at bit depth.

Step size turns into visible width on screen. Take a full-screen ramp from black to white across a 3,840 pixel wide 4K image. At 8-bit, 256 levels leave each step about 15 pixels wide (3,840 divided by 256). At 10-bit, 1,024 levels shrink each step to about 3.75 pixels (3,840 divided by 1,024), narrow enough that most eyes read it as smooth. Real skies are harsher than that ramp because they span a narrow range. Fora Soft's example ramps from code value 90 to 110 over 400 pixels: only 20 steps at 8-bit, so bands about 20 pixels wide. The same ramp at 10-bit has about 80 levels and bands near 5 pixels.

Where banding comes from: signal, codec, panel

Compression is the second source. Encoders quantize away faint variation, and banding shows up only in smooth, low-texture regions such as skies, walls, and fades, exactly the places where the encoder has no detail to spend bits on. Netflix says the high bit depth of its AV1 streams helps deliver subtle details and minimizes the risk of banding (see AV1). Fora Soft adds a warning for anyone measuring it: a banded 8-bit sky with about one code value of average error scores near 48.1 dB PSNR, which looks almost perfect on paper. Streaming engineers use the CAMBI metric instead, which runs from 0 (no banding) to about 24 (unwatchable), with a score near 5 reading as slightly annoying. The wider streaming picture is in streaming compression artifacts.

The panel is the third source. RTINGS reports that most modern TVs accept a 10-bit signal, but the majority do not use native 10-bit panels. They use Frame Rate Control, a form of temporal dithering in which a pixel flashes quickly between two neighboring colors so the eye averages them (see dithering and FRC). The processing chain is the last source: RTINGS lists Dynamic Contrast and white calibration settings as features that can add banding on their own.

Native 10-bit vs 8-bit plus FRC

The spec sheet label does not decide the result. RTINGS states that an 8-bit TV using dithering can show a 10-bit color depth and can even have smoother gradients than a native 10-bit panel, so it scores the end result and does not separate the two designs. In its HDR Native Gradient test, the Samsung S90D/S90DD OLED had the best gradient handling of any TV RTINGS had tested at the article's publication, with only very minor banding in the 100% black to 50% green line. The Sony A80J OLED had the worst, with visible banding in almost every line.

Resolution does not help. RTINGS is explicit that an 8K TV has no inherent advantage over a 4K TV, because resolution counts pixels while color depth counts the shades each pixel can show.

How reviewers test it, and what to change

RTINGS builds its test pattern in Photoshop as a 4K image (8K for 8K models) with 16-bit color depth, converts it to a 10-bit HDR10 RGB full-range video, and plays it from a Murideo Seven signal generator. The pattern has eight lines: black to 50% gray, 50% gray to white, and the same two-stage ramp for red, green, and blue. Each line carries 12.5% of the score, which RTINGS assigns by judging the banding in each line. The TV's gradient smoothing features are switched off, hence the word native in the test name.

At home, the order of operations is signal first, then settings. RTINGS says a 10-bit source on a TV that can display 10-bit color is the requirement for minimal banding, and that external devices such as a UHD Blu-ray player or a console need the TV's enhanced signal format enabled for that HDMI input, because leaving it off may cause banding. If banding remains, turn off Dynamic Contrast style processing, then try the TV's smoothing control. RTINGS lists the names: Hisense Smooth Gradient, LG Smooth Gradation, Samsung Noise Reduction, Sony Smooth Gradation, TCL Gradation Clear, and Vizio Contour Smoothing. These help, but RTINGS warns they also remove fine detail. If banding survives all of that, the TV has poor gradient handling and no setting fixes it.

Common confusions

Banding is not compression blocking: blocking is a square-grid artifact, while banding is contour lines inside a smooth area. Fora Soft also notes that dithering or debanding applied just before a lossy encode will not survive, because compression quantizes the added noise back out, so a clean source file does not guarantee a clean stream.

The last confusion is the phrase 10-bit TV. A 10-bit panel fed an 8-bit stream still bands, and an 8-bit panel with good FRC fed a 10-bit stream can look smoother than the native panel. Judge a set by measured gradient photos, not by the bit-depth line on the box. For setup priorities on a new set, see the TV calibration settings guide, and for how panel technologies differ in processing quality, see TV panel types explained.