Stencil texture parameters

Image: The texture used by the Stencil texture. To use an image file, you must map a File texture to this parameter.
Mask: The transparency of the Stencil texture. You can use the Mask parameter either to control the overall transparency of the entire texture (by using the numeric field or slider), or to control the transparency of select regions of the texture (by mapping a texture to Mask). To use an image file, you must first map a File texture to this parameter.

For example, if the Stencil texture is mapped to a shader’s color, and the Mask value is 0.5, the resulting surface will be an even mix of the shader color and the Stencil texture color. If Mask is mapped with an image of a black circle on white, the Stencil texture color will appear inside the circle, and the shader color will appear outside the circle.

If you are using the Stencil texture an Overlay map, the Mask setting determines the degree to which the texture it was applied to can be seen through the Stencil texture. Overlay

The slider range is 0 (opaque) to 1 (transparent). The default value is 0.
Edge Blend: Controls the sharpness/softness of the edges of the texture. The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 0.

HSV Color Key

The HSV Color Key parameters control the chroma key masking of the Stencil texture.

Key Masking: Enables chroma key masking. The default setting is OFF. If Key Masking is OFF, all other HSV Color Key parameters have no effect.
Positive Key: Inverts the chroma key mask (only the colors specified in the Color Key and HSV Range are displayed). The default setting is OFF (the colors specified in the Color Key and HSV Range are masked).
Color Key: The color to be masked in the texture. The default setting is black. To mask a range of colors, you must also set the Hue/Sat/Val Range parameters.
Hue Range: The range of hues (H) centered on the Color Key color which will also be masked. The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 0.5.
Sat Range: The range of saturations (S) centered on the Color Key color which will also be masked. The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 0.5.
Val Range: The range of values (V) centered on the Color Key color which will also be masked. The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 0.5.
Threshold: The point at which the color state changes. The valid range is 0 to infinity. The slider range is 0 to 1. The default value is 0.5.