Reduce PWM and temporal dithering

This tutorial covers two ways to reduce changes in light output: keep hardware brightness above a chosen minimum, or turn off GPU dithering where supported. Which method helps depends on your display. Neither setting guarantees a flicker-free result.

Before you begin

PWM (pulse-width modulation) varies light output by rapidly switching a backlight or pixels. Temporal dithering alternates color levels to represent intermediate shades. These are different processes, and a monitor may use its own processing after receiving the Mac's image.

Change one setting at a time and keep a record of the starting values. Use panel-specific documentation or measurement to identify modulation behavior. The brightness level at which PWM changes depends on the display. A screenshot cannot measure PWM or temporal dithering. These settings are not a guaranteed remedy for eye strain.

Keep a hardware brightness floor

This method needs working hardware brightness and software dimming. Below the chosen hardware floor, combined brightness makes the image darker in software rather than lowering hardware brightness further.

  1. Open Settings > Displays > [display] > Image Adjustments.
  2. Keep Enable software-based video adjustments on and enable Combined brightness. Check that its status names an active hardware controller.
  3. Open Image Adjustment Settings….
  4. Set Combined brightness - minimum allowed hardware brightness level to the floor appropriate for your tested display. The accepted range is 0–99% on the hardware controller's scale. This can differ from the combined slider's percentage.
  5. Lower the combined brightness slider and compare the result. Confirm on the display's own brightness readout or with measurement that hardware brightness stays above the chosen floor while software dimming supplies the darker image.

Image Adjustment Settings with an illustrative 10% minimum hardware brightness

The 10% hardware floor is an illustrative setting, not a tested PWM threshold.

Check the result

The desktop should dim below the floor without requesting lower hardware brightness through that combined controller. This does not prevent modulation that exists at higher brightness, inside panel processing, or when another app or the monitor's own settings change brightness.

Software dimming reduces pixel values and can change contrast, black appearance or color precision. If hardware brightness control is unavailable, set brightness manually on the monitor and use software dimming in BetterDisplay. The hardware-floor setting needs a working hardware controller.

Turn off exposed GPU dithering on Apple silicon

  1. Open App Menu > [display] > Color Mode, usually beneath the more-options chevron.
  2. If GPU Dithering is shown and active, select it to turn it off. Its absence means the app cannot read that setting for the selected display.
  3. Compare a gradient and an ordinary document. Watch for banding and decide whether the tradeoff suits your setup.

Studio Display XDR Color Mode menu with GPU Dithering turned off

GPU Dithering is off for the exposed framebuffer setting.

Check the result

The GPU Dithering item should show its off state after a successful change. BetterDisplay remembers that exposed setting for the display, but the monitor may still apply its own frame-rate control or other dithering. The dithering FAQ explains this distinction and the interaction with Uniformity Correction on supported built-in panels.

Choose a lower color depth when available

On Intel, inspect Color Depth for an available 8-bit mode. On Apple silicon, inspect Color Mode for an 8-bit connection format at your chosen resolution and refresh rate. Check the full SDR/HDR and encoding description before selecting it. An 8-bit choice may not be available for your connection.

Selecting an 8-bit signal and disabling GPU Dithering are separate operations. Neither changes the monitor's internal panel processing. Mirroring a virtual screen does not guarantee an 8-bit or dithering-free result. Virtual screens can offer HDR modes, and the monitor still uses its own connection and processing. If you experiment with an SDR virtual source, use the virtual-screen setup tutorial and verify the actual result on your hardware.

Optional: create a limited-color appearance

For a simpler document appearance, open App Menu > [display] > Image Adjustments and move Quantization toward fewer color levels where available. It reduces the number of represented color levels, deliberately producing steps between shades.

On supported Apple silicon displays, Color Mode > Grayscale Appearance removes color. Combine it with quantization if you prefer an e-book-like appearance. These effects change the image. They do not establish whether hardware dithering or PWM has stopped.

Studio Display XDR Image Adjustments menu with Quantization set to five levels through the compositor

Quantization is set to five levels through the compositor. The adjustment also changes the captured desktop and menu.

Native Preview sample with grayscale and color gradients stepped by BetterDisplay Quantization

Quantization is set to five levels, producing stepped gradients in this sample through the compositor adjustment path.

Built-in Display Color Mode menu with Grayscale Appearance applied and its action row highlighted

Grayscale Appearance is applied to the built-in display. The action row is highlighted here.

Troubleshooting

If the hardware floor has no effect, confirm Combined brightness is active and test the combined slider rather than an independent hardware slider. Check for monitor auto-brightness or another app changing hardware brightness outside BetterDisplay.

If GPU Dithering is missing, check the selected display and architecture. The toggle requires an exposed Apple silicon framebuffer setting. If gradients show bands after turning it off, restore the original setting or review the Uniformity Correction interaction. Hardware measurements are needed to confirm a completely modulation-free result.

Undo the setup

Clear the custom hardware floor to restore its default, or return to your recorded value. Re-enable GPU Dithering if it was originally on, restore the previous color format, and choose Standard Appearance to undo framebuffer grayscale. Reset Quantization separately through Image Adjustments.

Additional information

This section explains feature access and platform requirements for this tutorial.

Features requiring Pro license

The combined minimum hardware brightness setting requires Pro. GPU Dithering and the exposed framebuffer appearance actions are not independently Pro-gated. Quantization and the Color Temperature slider require Pro, as do the custom virtual-screen methods. Basic software dimming has no separate Pro gate.

Platform compatibility

The hardware-floor method is available on Apple silicon and Intel when working hardware brightness and combined software dimming are available. GPU Dithering and framebuffer Grayscale Appearance require supported Apple silicon displays. Color-depth choices depend on architecture, connection, display mode and GPU. The monitor's own processing needs separate verification.