Parameters

 Type- this is the type of transformation used. These are the possible types: 

• Linear - this mode will simply multiply the final image colors based on their brightness without applying any changes.
• Exponential - this mode will saturate the colors based on their brightness. This can be useful to prevent burn-outs in very bright areas (for example, around light sources, etc.). This mode will clamp colors so that no value exceeds (255, or 1 in floating point value).
• HSV Exponential - this mode is very similar to the Exponential mode, but it will also preserve the color hue and saturation, instead of washing out the color towards white.
• Intensity Exponential - this mode is similar to the Exponential one, but it will preserve the ratio of the RGB color components and will only affect the intensity of the colors. 
• Gamma Correction - this mode applies a gamma curve to the colors. In this case, the Dark multiplier is a general multiplier for the colors before they are gamma-corrected. The Bright multiplier is the inverse of the gamma value (i.e. for gamma 2.2, the Bright multiplier must be 0.4545). This is a deprecated mode, do not use it.
• Intensity Gamma - this mode applies a gamma curve to the intensity of the colors, instead of each channel (RGB) independently. This is a deprecated mode, do not use it.
• Reinhard - this mode is a blend between exponential-style color mapping and linear mapping. If the Burn value is 1.0, the result is linear color mapping and if the Burn value is 0.0, the result is exponential-style mapping.

Dark multiplier - this is the multiplier for dark colors. 

Bright multiplier - this is the multiplier for bright colors.

Gamma - this parameter allows the user to control the gamma correction for the output image regardless of the color mapping mode. Note that the value here is the inverse of the one used for the Gamma correction color mapping type. For example, to correct the image for a 2.2-gamma display, you should set the Gamma parameter simply to 2.2.

Input Gamma - specifies the gamma of the textures used in the scene

Sync With Gamma - when enabled sets Blender's "Color Management" Gamma to 1

Affect background - if this is off, color mapping will not affect colors belonging to the background.

Sub-pixel mapping - this option controls whether color mapping will be applied to the final image pixels or to the individual sub-pixel samples. In older versions of V-Ray, this option was always assumed to be on, however its default value is now off as this produces more correct renderings, especially if you use the universal settings approach.

Adaptation Only -when enabled neither color mapping nor gamma are burned into the final image. However, V-Ray will proceed with all its calculations as though color mapping and gamma are applied (e.g. the noise levels will be corrected accordingly). This can be useful, for example, if you know that you will apply some color correction to the image later on, but wish to keep the rendering itself in linear space for compositing purposes.

Linear Workflow - when this option is checked V-Ray will automatically apply the inverse of the Gamma correction that you have set in the Gamma field to all  VRayMtl  materials in your scene.

Clamp output - if this is on, colors will be clamped after color mapping. In some situations, this may be undesirable: for example, if you wish to antialias HDR parts of the image as well, turn clamping off.

 Clamp level - this option specifies the level at which color components will be clamped if the Clamp output option is on.