The Color Correction utility node allows the application of various color corrections to a texture, including adjustment of brightness, contrast, hue, saturation, and options for rewiring the RGB channels.

UI Path: ||Hypershade|| > Create panel > VRay section> Other Textures > VRay Color Correction

Color – Specifies the input color or texture to be corrected.

Rewire Red/Green/Blue/Alpha – Replaces the current channel with the chosen one:

Red – Assigns the red channel.
Green – Assigns the green channel.
Blue – Assigns the blue channel.
Alpha – Assigns the alpha channel.
Redinv – Assigns the inverse value of the red channel's value.
Greeninv – Assigns the inverse value of the green channel's value.
Blueinv – Assigns the inverse value of the blue channel's value.
Alphainv – Assigns the inverse value of the alpha channel's value.
Monochrome – Sets the channel to be monochrome (grayscale).
One – Assigns the value 1 (or the highest possible value) to the channel. For example, Rewire Red set to One gets the red channel a value of 255 (RGB, 0 to 255).
Zero – Assigns the value 0 (or the lowest possible value) to the channel. For example, Rewire Red set to Zero gets the red channel a value of 0 (RGB, 0 to 255).

Hue Shift – Specifies a value for the adjustment of the current color hue.

Saturation – Specifies a value for the saturation or desaturation of colors.

Hue Tint – Specifies a color that is used to tint current colors.

Tint Strength – Adjusts the strength of the hue tint.

Lightness Mode – Specifies the lightness mode that is used. You can choose between Standard and Advance mode.

Standard mode

Brightness – Adjusts the overall brightness of the image.

Contrast – Adjusts the contrast of the image.

Advanced mode

Exposure Mode – Specifies the exposure method.

Gain – In this mode, the Brightness value is a simple multiplier for the input colors.
F-Stops – In this mode, the Brightness value multiplies the color intensity with photographic F-stop exposure. Increasing the Brightness by one doubles the brightness, the same as increasing the Gain by 2. For example, this mode's input value of 1.0 and Brightness of 0.0 equals 1.0 (i.e., no brightness correction). Then, Brightness 1.0 corrects the input of 1.0 to equal 2, Brightness 2.0 corrects the input of 1.0 to equal 4.0, Brightness 3.0 corrects the input of 1.0 to equal 8.0 and so on. The input is multiplied by 2 to the power of the brightness value in this mode (<input> * 2 ^ <F-Stop Brightness>).
Printer Lights – When set with the same value as the Printer Lights Per Stop parameter is set, it doubles the luminance.

Brightness – Affects the brightness of the input colors based on the Exposure Mode.

Gamma/Contrast – Controls the gamma and contrast. Increasing gamma, decreases the contrast.

Base – The base value for Gamma correction. Pixel values equal to the Base are not affected. This can be useful when gamma-correcting a texture without changing certain luminance levels.

Offset – Adds a uniform offset to all pixel values.

Use Red/Green/Blue – When enabled, uses the corresponding channel for the individual RGB parameters.

RGB Brightness – Controls the brightness.

RGB Contrast – Same as Gamma/Contrast, but for the individual R/G/B channels.

RGB Base – Same as Base, but controls which pixel values in the individual R/G/B channels are unaffected by the RGB Contrast.

RGB Offset – Same as Offset, but adds a uniform offset to the individual R/G/B channels.

Printer Lights Per Stop – When Printer Lights Exposure Mode is used, this value specifies how many printer lights are equal to f-stop, doubling or halving the brightness.