Tones Range node
The Tones Range node selects a range of the input around a specified value.

Inputs
The Tones Range node requires a grayscale input texture.
Outputs
The Tones Range node provides a single grayscale texture.
Parameters
The Tones Range node accepts 4 parameters:
the Value around which the tones are selected
the Width (in tones space) of the gradient around the value
the Contrast of the gradient
the Invert option that will invert the result if checked