Color Banding: Why You See Stripes in Gradients and How to Fix It

What color banding looks like

Banding shows up where an image changes slowly from one shade to the next: a blue sky getting lighter toward the sun, a sunset, fog, smoke, a dark room lit by one lamp, or a plain background with a vignette. Instead of a seamless blend you see distinct bands or contour lines, sometimes with a slight color tint. It is also called posterization or false contouring.

RTINGS, which tests gradient handling on every TV and monitor it reviews, describes the two ways it goes wrong: shades that should look the same look clearly different, or shades that should look different are shown as the same. Either way the screen, or something before it, cannot show the exact shade asked for and groups it with a neighbor.

Banding matters most in films and games with dark scenes and skies, in HDR content, and in photo and design work where smooth gradients are part of the image.

Why banding happens: bit depth in plain numbers

A screen shows each color channel (red, green, blue) in a fixed number of levels:

Microsoft's Windows display documentation explains why this matters: higher bit depth lets you tell very similar colors apart without artifacts such as banding. Mainstream PC displays use 8 bits per channel, while the human eye needs at least 10 to 12 bits to avoid perceivable distortions. So even a perfect 8-bit chain can show faint steps in a wide, slow gradient.

Some quick math shows why. A full black to white ramp across a 3840 pixel wide 4K screen has 256 levels, so each level is 15 pixels wide. Up close on a dark gradient those 15 pixel steps can be visible even when nothing is wrong. What is not normal is steps that are uneven, much wider than their neighbors, tinted, or blotchy.

Dithering and FRC

Many screens show more shades than their panel natively has by dithering. RTINGS explains that most modern TVs showing a 10-bit signal use an 8-bit panel with Frame Rate Control (FRC), which flashes a pixel quickly between two neighboring shades so you see the average. On monitors, spatial dithering places two neighboring shades side by side instead. Done well, dithering can give smoother gradients than a native 10-bit panel; RTINGS scores the result, not the method. Done badly, it shows as faint banding or shimmer, usually in dark shades.

Screen, settings or source: find where it comes from

Banding can be created at any point between the file and your eyes. This table narrows it down in a few minutes:

Compression is the most common source by far. Research on debanding filters describes banding as a common distortion caused by compressing smooth regions with little texture, and says it can be very noticeable even in high quality video. RTINGS makes the same point from the other side: with real content, gradient quality depends heavily on what the source does to the image, which is why its own test uses a controlled signal generator.

How to test your screen for banding

1. Prepare. Browser zoom at 100%. Turn off night light, blue light filters and any dynamic contrast or eco picture mode, so you test the screen and not the filters.
2. Open the banding test with Smooth selected and go full screen.
3. Step through every gradient. The dark ramp and the sky gradient are the most revealing. Look for stripes, blotches, tinted bands and steps wider than their neighbors.
4. Check both directions. The test has a horizontal and a vertical gray ramp; banding and dithering do not always look the same both ways.
5. Calibrate your eye. Switch to 64, 32 and 16 steps to see what obvious banding looks like, then return to Smooth and compare.
6. Check the ends. Use the black level test to confirm the darkest and brightest patches are all visible, and the gamma test to confirm mid tones sit where they should.

How to fix color banding

Work from the cheapest fix to the most involved. Test again after each change so you know which one helped.

1. Turn off software color adjustments

Night light, blue light filters, color filters and "digital vibrance" style sliders change colors after the image is made, using the same 256 levels. EIZO explains the effect with calibration done on the computer: lower the color temperature in software and green and blue lose some of their 256 steps, and the same happens with gamma and brightness, which shows as banding from skipped gradations. A warm filter works the same way, so turn it off and compare.

2. Adjust brightness, contrast and color on the screen, not in software

Use the buttons or menu on the monitor or TV rather than brightness, contrast or gamma sliders in the graphics driver. Changes made in software or the driver work within the signal's 256 levels, so they can only lose steps: dim white to 80% in software and the 256 levels are squeezed into about 205. Controls on the screen act inside the monitor instead, and on screens with fine internal processing, such as the hardware calibrated monitors EIZO describes, they lose no steps at all.

3. Match full and limited range

Computers normally send full range (levels 0 to 255); video uses limited range (16 to 235). NVIDIA's control panel help describes the Output dynamic range choice, and notes that full range, where the display supports it, preserves black detail and white peaks. If one side sends limited and the other expects full, the 220 levels between 16 and 235 are stretched over 256, so some steps are skipped, and blacks look gray. The opposite mismatch crushes shadows. The black level test shows which one you have and how to fix it.

4. Use the highest color depth your setup supports

In the graphics driver, set the output color depth as high as the display accepts. NVIDIA's help says Output color depth sets bits per color according to what the display supports, and that bandwidth limits can hide 10 bpc at a given resolution and refresh rate. RTINGS recommends a 10-bit signal to avoid 8-bit banding, with the same bandwidth trade off. Keep expectations realistic: Microsoft notes that, before Windows Advanced Color, the desktop limited windowed apps to 8 bits per channel even when the display supported more, so everyday apps may still be 8-bit.

5. On a TV, turn processing off, then try gradient smoothing

RTINGS lists dynamic contrast and white balance calibration settings as things that can cause banding. Try a more neutral picture mode with dynamic contrast off. If banding remains, most TVs have a gradient smoothing option that hides it at the cost of some fine detail:

For HDR from a console, streaming box or disc player, RTINGS also advises enabling the TV's enhanced signal format setting for that HDMI input; leaving it off can cause banding.

6. Be careful with calibration

A software calibration (an ICC profile loaded into the graphics card) corrects color by remapping levels, which EIZO says risks losing gradations and adding banding. Monitors with hardware calibration store the correction inside the screen and pick from a finer internal table, which keeps gradients smooth. If a profile made banding worse, compare with it off.

7. Improve the source

If only certain videos band, the fix is in the content: a higher bitrate or resolution stream, an HDR or 10-bit version, or better export settings in your own renders.

What does not help

• More resolution. RTINGS notes resolution does not affect gradient handling: an 8K TV is not smoother than a 4K one because of its pixel count.
• A 10-bit panel on its own. Every link has to carry the extra levels: the content, the app, the operating system, the cable and the screen.

Gamma setting: what it does and which one to choose

Gamma describes the curve that turns pixel values into brightness. A higher gamma makes mid tones darker and the picture more contrasty; a lower gamma makes mid tones lighter and the picture flatter. It matters for banding because the curve decides how the 256 levels are spread between black and white, and because changing gamma in software throws levels away, as EIZO explains.

To set it, look for a Gamma option in the monitor or TV menu first; it is usually listed as numbers such as 2.2 and 2.4. Use the driver or operating system only if the screen has no option, and recheck banding afterwards. The gamma test lets you estimate where your screen sits now. Strictly, sRGB is not a pure 2.2 curve: its specification uses a short straight segment near black and a 2.4 exponent above it, which together approximate 2.2. For an exact result, calibrate with a hardware colorimeter.

Is color banding a defect?

Usually not in the warranty sense. Makers' pixel policies deal with faulty pixels, not with how smooth gradients look, and gradient handling is treated as a picture quality trait that varies between models. RTINGS' advice is that if banding remains after you have checked the settings and turned off processing, the display simply has poor gradient handling and there is not much more you can do.

• New screen with banding that settings cannot fix? Use the return window, and compare with reviews of the same model. If your unit looks much worse than reviewed units, ask for an exchange.
• Buying a new screen? Check the gradient results in detailed reviews, and whether it accepts a 10-bit signal at the refresh rate you want.
• Seeing lines that are sharp, straight and always in the same place? That is not banding. See lines on screen.
• Uneven brightness patches on dark scenes? That is a uniformity issue: see backlight bleed vs IPS glow.