Clamp Texture
The Clamp Texture node provides a minimum and maximum value to "clamp" the values of the texture map.
How to Use
Open the Node Editor and prepare the setup as you see in the image below. Use the Clamp Texture node to clamp the white color in the defined texture in the material. The texture to be clamped in the node setup is connected to the "texture" slot using the output from the "Image Texture" node. Two "RGB Spectrum" nodes were used for "min./max." values to keep the red and change the white color (RGB values are shown in the image). You can also use this node for other texture sources (e.g., noise, turbulence, marble etc.)