Fix Color Banding on an LG OLED Connected to a Mac

Quick Answer

Banding is not one problem. Before changing the TV, determine whether the visible steps are encoded in the video, introduced by HDR/SDR conversion, caused by the Mac's output path, or inherent to the panel near black. BetterDisplay can expose and manage supported macOS display modes, but it cannot restore missing source gradations or create bandwidth the hardware lacks.

Start with a trustworthy test

Use a locally stored, known-quality gradient or test pattern. Do not diagnose with a social-media image, streamed sky or heavily compressed video; compression itself can create contours. Compare:

• the same file on the Mac's internal display;
• SDR with HDR disabled;
• HDR with known HDR material;
• a built-in LG app or another HDMI source.

If every device shows the same bands in the same places, suspect the content. If only the Mac path differs, continue through the chain.

Check macOS output

Open Displays settings and record the selected resolution, refresh rate, HDR state and color profile. Avoid changing all four simultaneously. macOS exposes only modes supported by the Mac, adapter, cable and display handshake.

HDR can make an SDR desktop or SDR gradient pass through conversion. Compare HDR Off for ordinary desktop work. Enable HDR only when testing HDR content, then verify the content and application actually use the intended path.

Check the connection

• Connect directly where possible to eliminate docks and converters.
• Confirm the adapter supports the intended resolution, refresh and HDR combination.
• Try a known-good cable and a lower refresh rate as a diagnostic step.
• Use the LG PC input type when desktop chroma clarity is required.
• Keep source and TV video-range interpretation matched; forcing Full at one end only can crush or raise blacks.

A “10-bit panel” does not prove the current signal is 10-bit, and a 10-bit signal does not remove banding already present in the source.

What BetterDisplay can and cannot do

BetterDisplay can help inspect displays, create supported scaled/HiDPI modes and manage macOS display configuration. Features vary by Mac, macOS release, connection and BetterDisplay version. Do not promise a universal “Force 10-bit” or “GPU dithering” switch unless the current application and hardware explicitly expose it.

Use the project's current documentation to identify the available controls. Change one item, retest the same gradient and record the result. A HiDPI mode can improve text scaling but is not inherently a banding repair.

TV-side checks

Use a neutral Cinema or Filmmaker starting mode. Disable unusual color or contrast enhancements while diagnosing. Smooth Gradation, where available, may conceal some source contours but can also soften real detail; it does not repair the signal.

Near-black OLED uniformity or gradation can look different from bright gradient banding. Test at several brightness levels and avoid drawing a panel conclusion from one compressed pattern.

OLED Control can hold supported input and TV settings constant during comparison. It cannot configure the Mac GPU, bit depth, dithering or ICC pipeline.

Identify the shape of the artifact

Encoded banding forms rings or steps that move with a sky, fog bank or spotlight. Compression macroblocks pulse around moving shadows. Panel vertical banding stays fixed to screen coordinates across unrelated scenes. A Full/Limited mismatch crushes several near-black shades together. These cases need different fixes.

Take a macOS screenshot. If the staircase remains when that file is viewed on another known display, the artifact exists before HDMI. If the screenshot is smooth but the photographed LG is not, continue through output and panel.

Build a clean Mac-to-TV baseline

Connect the Mac directly without dock, receiver or capture device. Select native 3840×2160 and a conservative supported refresh. Turn HDR off for an SDR gradient and use the LG PC input type. Reset only the active picture mode and disable Dynamic Contrast, high Sharpness and aggressive noise processing.

Once the SDR baseline is understood, add higher refresh, HDR and intermediaries separately. The first step that reintroduces banding identifies the branch.

HDR and color-profile checks

Apple documents specific Mac/display requirements for HDR. Merely turning on HDR does not make SDR source 10-bit HDR; macOS maps SDR into the HDR desktop. Compare native HDR video in an HDR-capable application with SDR content under HDR conversion.

Return to a standard/known color profile during diagnosis. A custom ICC profile can improve measured color but cannot increase HDMI bit depth. Remove Night Shift, accessibility color filters and app-specific video enhancement from the comparison.

BetterDisplay workflow

Use BetterDisplay first to inspect the active display and choose a supported HiDPI/scaled mode. Save the original configuration. Change one option, re-open the same local gradient and record the result. Consult current release documentation because labels/capabilities change.

Do not enable undocumented override combinations from screenshots for another Mac. Apple Silicon model, USB-C/HDMI adapter, macOS and EDID all affect availability. If the tool reports no 10-bit/dithering control, that absence should not be “fixed” by a guessed command.

Cable, adapter and bandwidth

A link failure usually causes blackouts, colored sparkles or reconnects, not smooth contour bands. Still, an adapter can limit refresh/chroma/bit depth. Lower refresh as a diagnostic and use an adapter explicitly supporting the intended Mac output. A cable carrying 4K60 may not prove a more demanding mode.

TV processing decision

Smooth Gradation Low can conceal mild source steps. Compare texture in grain, stars, skin and fine walls. If detail disappears, leave it Off. Do not alter white balance/CMS or run Pixel Cleaning for moving source contours.

For fixed vertical panel bands, allow normal use and automatic standby compensation, then document severe normal-content visibility for LG.

Mac banding FAQ

Does HiDPI increase bit depth?

No. It changes rendering scale, not necessarily transport precision.

Can BetterDisplay force every Mac to 10-bit?

No. It can expose supported configuration; hardware, OS and connection remain constraints.

Why is banding worse with HDR on?

SDR-to-HDR mapping may stretch existing steps, or the app/output path may differ. Test native HDR separately.

Does Smooth Gradation repair the file?

No. It blends visible boundaries at the cost of potential texture.

Sources

• Apple — Play HDR video on Mac
• Apple — Change your display's refresh rate
• BetterDisplay — Official documentation and source