Troubleshooting

Gamma is not changing

You may experience that the screen color doesn't change in any way, despite LightBulb being enabled. Here's what you can try in such cases:

• Make sure latest Windows updates are installed.
• Update GPU drivers.
• Monitors connected via DisplayLink don't allow changing gamma by default. Refer to this post to enable this feature.
• If you've installed TeamViewer you may have also installed its own display driver which doesn't support changing gamma. You will have to uninstall the driver (no need to uninstall the software). More info here.
• Disable integrated GPU in BIOS if you're using a discrete GPU, as it may cause interference. More info here.

Cursor is not affected by gamma changes

When hardware cursor rendering is enabled, your mouse pointer is rendered by the GPU on a separate layer, thus preventing it from being affected by LightBulb.

In some cases, you should be able to disabled hardware cursor rendering in GPU settings. Otherwise, a common workaround is to change your cursor to a darker/black color scheme.

Another workaround is to enable cursor trail, as explained here.

Gamma conflicts with other applications

Some applications may also try to override gamma settings, especially games. In cases where both the application and LightBulb are regularly refreshing gamma, the screen may either flicker or changes by one of the sides may not be seen. Most of the time, you can disable changing gamma in other applications so that they don't interfere.

Can't set a hotkey

If a hotkey is already registered by another application, you will not be able to use in LightBulb. If you try to assign a hotkey which is already in use, LightBulb will not even know it was pressed at all.

Refer to this issue for more info.