Viz Artist User Guide

Version 3.13 | Published March 28, 2019 ©

Chroma Keyer

This Shader clear regions in a video defined by a color. The color-space of this Shader is YUV, which is defined as following:

The luminance (Y) component determines the brightness of the color, while the U and V components determine the color itself (the chroma). Luminance (Y) ranges from 0.0 (dark) to 1.0 (bright). U and V ranges from -0.5 to 0.5.

Note: This plug-in is located in: Built Ins -> Shader -> Effects

Chroma Keyer Properties


  • Video: Sets the input video channel for keying. Be sure that for the set video channel the Keying Mode has been set to M-Zone (see Keying Mode).

  • Blend: Sets the alpha for the key signal.

  • Fit: Alters size to fit Screen or Object.

  • Invert: Flips the key signal.

  • Sampling Filter:

    • Nearest: Takes color information from one pixel.

    • 1D-Filter: Takes color information after applying a 1D-linear filter.

    • 2D-Filter: Takes color information after applying a 2D-linear filter.

  • Luminance: Sets the luminance.

Basic parameters for first method:

  • HueAngle: Selects the color to key in YUV space.

  • OpeningAngle: Determines tolerance for the color in YUV space.

  • KeyGain: Determines gradient for borders to neighboring colors (1=soft, 10=sharp).

  • SatMin: Determines lower saturation limit for keyed colors.

  • SatMinGrad: Determines gradient for lower saturation limit (0=sharp, 1=soft).

  • SatMax: Determines upper saturation limit for keyed colors.

  • SatMaxGrad: Determines gradient for upper saturation limit (0=sharp, 1=soft).

Basic parameters for second method:

  • U-Color: Determines U-value for color keying.

  • V-Color: Determines V-value for color keying.

  • UV-Diameter: Removes all colors between the reference UV and this diameter.

  • UVGradient: Determines gradient for fade out at diameter border (0=sharp, 1=soft).

Removing keying from Highlights and Shadows:

  • LumMin: Sets lower luminance limit for keyed colors.

  • LumMinGrad: Sets gradient for lower luminance limit (0=sharp, 1=soft).

  • LumMax: Sets upper luminance limit for keyed colors.

  • LumMaxGrad: Sets gradient for upper luminance limit (0=sharp, 1=soft).

Sampling reference point:

  • UVRangeCheck: Obtains information about the sampled color.

  • URangeMin: Defines the minimum UColor that should be accepted.

  • URangeMax: Defines the minimum UColor that should be accepted.

  • VRangeMin: Defines the minimum UColor that should be accepted.

  • VRangeMax: Defines the minimum UColor that should be accepted.

  • SampleTrustiness: Determines percentage of samples in the limited UV-Color space.

  • Pos. X: Deternines X-coordinate for sampling.

  • Pos. Y: Deternines Y-coordinate for sampling.

    Note: The origin of the coordinate system is in the upper left corner.

  • Width: Sets number of pixels in x-direction.

  • Height: Sets number of pixels in y-direction.

  • Sample at Pos: Replaces XY-coordinates of the object center if Pos. X and Pos. Y are enabled. If disabled, the XY-coordinates are set by values in the interface.

  • Get Sample: Samples another time the reference point.

See Also