Walker Effects Manual

Channel Composite

This plug-in provides the ability to directly composite layer channels, with many advanced options such as built-in Levels, Masks, Blur, and Composite Modes. Channel Composite can easily be used to do a number of complex operations:

- Remap any channel to any channel.
- Composite directly to channel.
- Combine multiple channels.

The capabilities of this plug-in make it a powerful tool for working with mattes. The alpha channel can be directly manipulated with levels, masks, blur and compositing.

Generally, a good starting point for Channel Composite is to specify the Source 1 Channel and the Destination Channel. For example, if you wanted to work on the transparency of a layer you would specify the Source 1 Channel to be Alpha and the Destination Channel to also be Alpha. With the default settings, Channel Composite will simply pass the input channel to the output without modifying it. From here you can then adjust the Source 1 Levels and Mask controls, directly affecting the matte.

View Mode

This menu allows you to isolate different aspects of Channel Composite. Each mode modifies the render output and the available controls so that you can easily work with the plug-in to dial in the settings. The following modes are available:

Source 1 Layer

Choosing this View Mode will display the original input layer for Source 1, as specified by the Layer control. If None is selected, then the layer on which the plug-in is applied will be shown. In this mode, only the Source 1 Layer control will be enabled.

Source 1 Channel

Using this View Mode allows you to directly see the input channel making it easy to select the best channel for your needs. In this mode, Invert and Premultiply With Alpha can be used, but Levels and Mask are disabled.

Source 1 Mask

This mode displays the Mask for Source 1. If no path is selected, or it is invalid, a red X will be rendered instead. This View Mode is very helpful for dialing in the masking controls without confusion with other aspects of the plug-in.

Source 1 Output

The final processed input channel, including Mask and Levels, is displayed by this View Mode. This is helpful to work with the Source 1 options independently.

Source 2 Layer, Channel, Mask, Output

The Source 2 View Modes work the same as the Source 1 options, but of course display the elements specified by the Source 2 controls. Note: These View Modes will only work if the Compound Channel is enabled. Otherwise a red X will be rendered.

Composite

The Composite View Mode renders the final processed output of Channel Composite. It takes into account all of the effects settings and renders the output to the Destination Channel.

Source 1

The Source 1 group is the basic input into Channel Composite. This provides the basis for building more complex operations.

Layer

The Layer specifies the input layer for Source 1. If None is selected, then the layer on which the effect is applied will be used. When choosing a layer, set the View Mode to Source 1 Layer in order to see it directly.

Channel

The selected Channel will be extracted from the Layer. Because Channel Composite only works with single channels, there is no option to work with full RGB. You can use the View Mode option Source 1 Channel to see the channel by itself with the Invert and Premultiply options included.

Invert

If this checkbox is enabled the selected Channel will be inverted. Invert is calculated before Premultiply With Alpha.

Premultiply With Alpha

Turn this checkbox on in order to render the Channel premultiplied with its alpha channel. This option is generally used for layers that have transparency.

Blur

These controls provide blurring for the Source 1 channel. Blur is only rendered when the amount is greater than 0. Otherwise, the group name will read 'Blur Off' and will be disabled.

Blur Quality

To help maximize rendering efficiency, this menu allows you to decide what type of blur is used. You can choose from Fast Blur or Gaussian. When set to Automatic, the effect will render the Gaussian Blur for best quality and Fast Blur for draft quality.

Uniform Blur

This checkbox controls whether the blur is applied equally in the horizontal and vertical directions. If it is turned off, separate sliders for Blur X and Blur Y will become available.

Blur After Levels

Applying blur before or after Levels can produce dramatically different results. This checkbox allows you to choose the rendering order to have maximum flexibility in using the blurring and levels features.

Levels

The Levels controls can be used to modify the grayscale values of the Channel and is useful for both fine-tuning and dramatic changes. These controls work similarly to the standard Levels filter in After Effects.

Input Black

As the Input Black is increased, the channel becomes darker. Visually it appears as though the darker areas grow, eventually overtaking all pixels. The Input Black and Input White values can be moved closer together to create contrast.

Input White

Opposite of Input Black, Input White increases the range of white pixels. As the value is decreased, the brightness of the image increases until the whole image becomes white. When the Input White value is less than the Input Black, the Channel value will be inverted.

Gamma

The grayscale levels between white and black can be biased towards either end of the spectrum using Gamma. At the default value of 1.0, the interpolation from black to white is even. Gamma values less than 1.0 bias the gray levels towards black, creating a darker image with more contrast. When the Gamma value is greater than 1.0 the gray values are pushed towards white brightening the image and reducing contrast.

Output Black

The Output Black value clamps the resulting Channel value at the Output Black level. For example, if Output Black is set to a value of 45, then no pixel in the resulting Channel will be darker than 45.

Output White

Output White limits the maximum brightness of the Channel. For example, if Output White is set to 128, then no pixel in the resulting matte will be greater than 128.

Mask

Layer masks can be used with Channel Composite similarly to how they are used in the Timeline Window by After Effects. The Mask group is only active when a valid Path is chosen and the Enable checkbox is on. Paths must be closed. Whether the Mask is active or not is indicated by the word 'On' or 'Off' next to the Mask group name.

When the Use All Paths option is on, the name of the Mask group will change to reflect the current usage of paths (ie 'Mask On: Using[1,2,4]').

Important: Masks used by this plug-in should be turned off in the Timeline Window by setting their mode to None. Otherwise, the mask will be applied to the layer by After Effects as well. Furthermore, none of the mask controls in the Timeline Window are used. All settings regarding masks are controlled within the effect.

Path

To specify a mask, select the desired path from this menu. You may instead choose to Use All Paths, in which case this control will become disabled.

Use All Paths

With this option, it is not necessary to explicitly select a path. Instead, all available closed paths are used. Open paths will be ignored, while all closed paths are combined together as though they are one. The paths used are indicated by number in the name of the Mask group.

Uniform Feather

Enabling this checkbox means that mask feathering will be equal in the horizontal and vertical directions. Only one Feather slider will be provided. When this checkbox is unchecked, there will be two sliders for feather: Feather X and Feather Y. Note that the feather controls in the Timeline Window are ignored by this effect, and when using multiple paths they are all given the same feather amount.

Feather

This slider controls the size of the feathering in pixels. The feather is actually rendered by After Effects using the built-in masking tools, and will perfectly match results you get with standard masking. You can turn off Uniform Feather in order to control the feathering amount independently on the X and Y axis. In this case, to sliders will appear: Feather X and Feather Y.

Invert

When invert is on, the Mask will be rendered inverted. This essentially controls whether the mask region is included or excluded.

Mask Mode

To control how the Mask interacts with the Channel you can specify the Mask Mode. The default Mask Mode is Multiply, which produces the most commonly expected result. However, you can use any other mode to subtract, add, or otherwise affect the Channel with the Mask.

Mask Opacity

The Mask Opacity controls how much the Mask affects the Channel. With a value of 0, the Mask is not rendered, and at a value of 100 the Mask is fully applied. Note that Mask Opacity behaves differently than the mask opacity in the Timeline Window.

Compound Channel

In order to build more complex compositing operations with Channel Composite, the Compound Channel can be used to combine a second channel with the first. For example, you could subtract the opacity (alpha channel) of one layer from another.

Enable

Whether the Compound Channel options are used or not is controlled by the Enable checkbox. When this is turned on, all of the controls listed below will become available. Note: In order to use the View Mode with any of the Source 2 settings, the Compound Channel must be Enabled. Otherwise a red X is rendered.

Source 2

The Source 2 group provides the second input source for Channel Composite. If the Layer is set to None, then the layer on which the effect is applied will be used as input. For detailed explanations of the Source 2 controls, refer to the Source 1 documentation above.

Composite Mode

How the Source 2 channel is combined with Source 1 is controlled by the Composite Mode. All of the standard single channel composite modes are available. Note: Compositing of Source 1 and Source 2 is done after processing each channel individually, applying the Levels, Matte, and other options first.

Composite Behind

If this option is enabled, the compositing order of Source 1 and Source 2 will be reversed, effectively compositing Source 1 over Source 2.

Opacity

This controls how much the Source 2 channel is composited with Source 1. Which layer is in front is controlled by the Composite Behind checkbox. When Composite Behind is off the Source 1 channel is in the background. A value of 0 will leave the background channel unchanged, while a value of 100 will fully composite Source 2 with Source 1.

Destination Channel

The result of Channel Composite is output to the channel specified by this control. If you are not interested in replacing any particular channel, you can simply set this option to Grayscale, which is the default setting.

If you do specify the Destination Channel, the result of the plug-in will replace the contents of the channel. For example, you could set Destination Channel to Alpha, in which case only the alpha channel of the layer will be affected by the plug-in.

Advanced Output Options

In addition to replacing a channel you may also choose to composite the output channel with the original channel of the layer. This makes it possible to add or subtract parts of an existing channel quickly and directly.

Composite With Existing

To enable the Advanced Output Options, you must turn on this checkbox. This will allow you to composite the output of Channel Composite with the Destination Channel. If this checkbox is off, then Channel Composite will simply replace the Destination Channel.

Composite Mode

This sets the mode to use in combining the new channel created by Channel Composite with the Destination Channel.

Opacity

This controls how much the output is composited over the Destination Channel. At a value of 0, Channel Composite will have no effect on the Destination Channel, while a value of 100 will fully composite the channels.

Blend With Original

Use this slider to blend the result of the effect with the original input layer. If Blend With Original is set to 100, the effect will not render.