For a Bitmap, you can set or modify the following parameters under Output:
Invert: Inverts (reverses) the hues of the bitmap, like a negative color photo. Default = off.
Clamp: When on, this parameter limits the values of the colors to no greater than 1.0. Turn this on when you’re increasing the RGB Level, but don’t want the map to appear self-illuminated. Default = off.
Note: If you set the RGB Offset to a value greater than 1.0 while Clamp is on, all colors become white.
Alpha from RGB Intensity: When on, an alpha channel is generated based on the intensity of the RGB channels in the map. Black becomes transparent and white becomes opaque. Intermediate values are translucent according to their intensity. Default = off.
Output Amount: Controls the amount of the bitmap being mixed into a Composite material. Default = 1.0.
RGB Offset: Adds to the RGB values of the bitmap colors by the amount set by the spinner, which affects the tonal value of the colors. Eventually the bitmap becomes white and self-illuminated. Lowering the value decreases the tonal value towards black. Default = 0.0.
RGB Level: Multiplies the RGB values of the bitmap colors by the amount set by the spinner, which affects the saturation of the color. Eventually the bitmap becomes fully saturated and self-illuminated. Lowering the value decreases the saturation and makes the bitmap colors grayer. Default = 1.0.
Bump Amount – Adjusts the amount of bumpiness. This value has an effect only when the bitmap is used as a bump map. Default = 1.0.
For example, suppose you have a map instanced for both the Diffuse and the Bump components. If you want to adjust the amount of bumpiness without affecting the Diffuse colors, adjust this value, which changes the amount of bumpiness without affecting the map’s use in other material components.