Reduce banding with GIMP

Image: CC BY 4.0 by cybrkyd

When working with gradients, it is inevitable that banding will occur where the colours meet and change. To reduce and smooth out the transitions, a little dithering is needed. This is the process I employ in GIMP v2.0+.

With your affected layer selected:

Select Colours > Dither… from the top menu.
Ensure the Dithering method is set to Floyd-Steinberg.
Set the Opacity to between 1 and 5, depending on the level of banding.
Press OK.

GIMP dither

In most cases, the above steps are enough to reduce the banding effect. However, for some stubborn images, it is worth considering the addition of some extra noise or grain to the image.

Filters > Noise > Spread… works generally well at a low opacity.

The gradient example below proved especially difficult, so it required some noise. Here is a side-by-side comparison of before and after.