The Clamp Texture provides a minimum and maximum value to "clamp" the values of an incoming texture map. In the example shown in Figure 1, the material on the bottom has the Turbulence texture connected to the DiffuseAmount of diffusion, or the reflection of light photons at different angles from an uneven or granular surface. Used for dull, non-reflecting materials or mesh emitters. channel of an Octane shader. The material on the top shows the same turbulence texture passing through a Clamp node and then connected to the Diffuse channel of another Octane shader. The clamp values are set to a minimum of 0.1 and maximum of 0.3. The result is much less contrast than the material on the bottom.
Figure 1 : A Clamp texture node is used to reduce the contrast of a turbulence texture.