V-Ray Layered Texture

V-Ray Layered is a texture utility for merging or compositing textures or images using various blend modes or texture masks.

Textures – Specifies the number of textures that are layered together.

Layer Name – Specifies a name for the layer.

Mode – Sets the merge algorithm to use for the layer. 

None – The current layer covers the composite where the images overlap. If the current layer is completely opaque, the resulting image consists entirely of the current image. Use this option for Texture 1 when setting up the base texture for a composite.
Average – The average of the composite and the current texture. The result is darker than the two images.
Add – The sum of the current texture and the composite. Pixel values over 1.0 are clipped to 1.0.
Subtract – Subtracts the current texture from the composite.
Darken – Takes the minimum (darkest) values of the current texture and the composite.
Multiply – Multiplies the values of the current layer and previous layer. Note that multiplying two negative values does not yield a positive number.
Color Burn – Darkens the composite color to reflect the current texture color by increasing the contrast between the two. Blending with white produces no change.
Linear Burn – Darkens the composite color to reflect the current texture color by decreasing the brightness. Blending with white produces no change.
Lighten – Takes the maximum (lightest) values of the current texture and the composite.
Screen – Multiplies the composite with the inverse of the current layer. Screening with black leaves the color unchanged. 
Color Dodge – Brightens the composite to reflect the current texture by decreasing contrast between the two. Blending with black produces no change.
Linear Dodge – Brightens the composite color to reflect the current texture by increasing the brightness.
Spotlite – Acts like Multiply but with twice the brightness.
Spotlite Blend – Acts like Spotlite but also adds ambient illumination to the result from the composite above this layer. 
Overlay – Multiplies or screens the colors of the composite, depending on the brightness values of the current texture.
Softlight – Adds or subtracts the values of the composite, depending on the brightness of the current texture.
Hardlight – Multiplies or screens the colors of the composite, depending on the brightness values of the current texture.
Pinlight – If the current texture is lighter than 50% gray, pixels darker than the defined texture are replaced, and pixels lighter than the defined texture do not change. If the defined texture is darker than 50% gray, pixels lighter than the defined texture are replaced, and pixels darker than the defined texture color do not change.
Hardmix – Changes all pixels to primary additive colors (red, green, or blue), or white or black, depending on the colors in the current texture.
Difference – Subtracts either the composite from the current texture or the current texture from the composite, depending on which has the greater brightness value.
Exclusion – A more photographic form of Difference. 
Hue – Uses the hue of the current texture and the saturation and value of the composite to form the resulting image. However, if the saturation of the current texture is zero, the hue is taken from the composite.
Saturation – Uses the saturation of the current texture and the hue and value of the composite to form the resulting image.
Color – Uses the hue and saturation of the current texture and the value of the composite to form the resulting image.
Value – Uses the brightness value of the current texture and the saturation and hue of the composite to form the resulting image.

Blend – Specifies the amount of blending between the composite and the current layer. The default value of 1 uses the full amount of the effect of the current layer's contribution when modified by its Blend Mode. When this parameter is 0 the current layer's contribution is fully transparent. Values between 0 and 1 make the current layer's contribution transparent to a degree.

Default Color – Specifies the color when there are no valid UVW coordinates.

Mult – Specifies a strength multiplier for the texture color.

Offset – Color corrects the texture by adding the RGB color values specified here to the RGB color values in the texture.

Invert – When enabled, inverts the resulting texture color.

Source – Specifies where the alpha channel is drawn from.

Alpha – Alpha channel is drawn from the texture.
Color – Alpha is generated from pixel intensity.
Opaque – Alpha channel is fully opaque.

Use – Differentiates between textures exported from different applications. You can choose between Color Intensity (3ds Max) and Color Luminance (Maya).

Mult – Specifies a multiplier for the texture alpha.

Offset – Specifies an additional offset for the texture alpha.

Invert – When enabled and Invert from Color Tweaks is also on, the resulting texture alpha is inverted as well.