S_Layer Layers the Foreground image over the Background using one of a variety of blending operations. The colors of each input can also be adjusted using the lights, darks, and saturation parameters. In the Sapphire Composite effects submenu. Inputs: Foreground:  The current layer.   The clip to use as foreground. Background:  Defaults to None.   The clip to use as background. Matte:  Defaults to None.   Specifies the opacities of the Foreground clip. If this input is not provided the Foreground alpha is used instead. These values are scaled by the Opacity parameter before being used.

Parameters:

Mode:   Popup menu,  Default: Normal.
Determines which blending method is used to combine the foreground and background pixel colors.

Normal:  a normal composite. This will just give the foreground as the result unless the Opacity is below 1.0 or an alpha channel is given.

Dissolve:  randomly replaces background pixels with foreground. The opacity determines the probability, so the foreground is more likely to replace the background for higher values of Opacity.

Multiply:  this can be used as an 'intersection' operation on matte images. White is the identity for Multiply, where one image contains white the other is not affected, so the result only contains white where both inputs are white.

Screen:  this can be useful for combining the bright areas of two clips. It can also be used as a 'union' operation on matte images. Black is the identity for Screen, where one image contains black the other is not affected, so the result is white where either of the input images is white.

Overlay:  combines foreground and background using an overlay function.

Soft Light:  darkens or lightens the background depending on the foreground.

Hard Light:  similar to Overlay but with foreground and background swapped.

Color Dodge:  brightens the background depending on the foreground.

Color Burn:  darkens the background depending on the foreground.

Darken:  the minimum of foreground and background. This can also be used as an 'intersection' operation with slightly different results than Multiply.

Lighten:  the maximum of foreground and background. This can also be used as a 'union' operation with slightly different results than Screen.

Add:  adds the foreground to the background.

Subtract:  subtracts the foreground from the background.

Difference:  similar to Subtract but the absolute value of the result is used, which tends to give more resulting colors in bounds. This can be used to select the regions of two matte images where one or the other is white, but not both.

Exclusion:  similar to Difference but with smoother results.

Hue:  combines the hue of the foreground with the saturation and luminance of the background.

Saturation:  combines the saturation of the foreground with the hue and luminance of the background.

Chroma:  combines the hue and saturation of the foreground with the luminance of the background.

Luminance:  combines the luminance of the foreground with the hue and saturation of the background.

Swap Inputs:   Check-box,  Default: off.
If enabled, effectively swaps the Background and Foreground inputs, and can be helpful for non-commutative operations like subtract. Note that this also causes parameters labeled 'Front' to affect the 'Back' input instead, and vice versa.

Fg Opacity:   Default: 1,  Range: 0 to 1.
Scales the opacity of the effect. When this is decreased the result approaches the background. At zero, the result will equal the background.

Fg Lights:   Default: 1,  Range: any.
Scales the Foreground before performing the effect.

Fg Darks:   Default: 0,  Range: -8 to 2.
Offsets the darker regions of the Foreground before performing the effect. This can be negative to increase contrast.

Fg Saturation:   Default: 1,  Range: 0 to 10.
Scales the color saturation of the Foreground before performing the effect. 0.0 makes it monochromatic, 1.0 has no effect.

Bg Lights:   Default: 1,  Range: any.
Scales the Background before performing the effect.

Bg Darks:   Default: 0,  Range: -8 to 2.
Offsets the darker regions of the Background before performing the effect. This can be negative to increase contrast.

Bg Saturation:   Default: 1,  Range: 0 to 10.
Scales the color saturation of the Background before performing the effect. 0.0 makes it monochromatic, 1.0 has no effect.

Result Lights:   Default: 1,  Range: any.
Scales the result after performing the effect.

Result Darks:   Default: 0,  Range: -8 to 2.
Offsets the darker regions of the result after performing the effect. This can be negative to increase contrast.

Result Saturation:   Default: 1,  Range: 0 to 10.
Scales the color saturation of the result after performing the effect. 0.0 makes it monochromatic, 1.0 has no effect.

Matte Use:   Popup menu,  Default: Alpha.
Determines how the Matte input channels are used to make a monochrome matte.

Luma:  the luminance of the RGB channels is used.

Alpha:  only the Alpha channel is used.

All Opaque:  an alpha of 1.0 is used as if the Matte were fully opaque.

Comp Premult:   Check-box,  Default: on.
Disable this if you have provided a separate Matte input and the Foreground pixel values have not been pre-multiplied by this Matte. This has no effect if Use Alpha is off.

Opacity:   Popup menu,  Default: Normal.
Determines the method used for dealing with opacity/transparency.

All Opaque:  Use this option to render slightly faster when the input image is fully opaque with no transparency (alpha=1).

Normal:  Process opacity normally.

As Premult:  Process as if the image is already in premultiplied form (colors have been scaled by opacity). This option also renders slightly faster than Normal mode, but the results will also be in premultiplied form, which is sometimes less correct.

See Also:

MathOps Sapphire Plug-ins Introduction

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