Apple Shake 4 - Manual (Page 530)

530 Chapter 19 Using Masks
Parameters Within the Mask Subtree
The Mask subtree, located in the top section of any node’s Parameters tab, contains the
following parameters that let you customize how the input mask image is used:
maskChannel
Lets you choose which channel to use as the mask. This parameter defaults to A
(alpha).
invertMask
Lets you invert the mask, reversing its effect on the image.
clampMask
Turning this parameter on clamps mask image data to a value between 0 and 1. It is
important to enable this parameter when using floating point images as masks.
enableMask
Lets you turn the mask off and on without having to disconnect it.
Using Masks to Limit Color Nodes
The following example uses images from the tutorial media directory ($HOME/nreal/
Tutorial_Media/Tutorial_Misc/masks) to show how to limit the effects of color nodes
using masks.
Masking a color-correction node to create a lighting effect:
1 In the Image tab, click the FileIn node, and select the car_bg.jpg, woman_pre.iff,
sign_mask2.iff, and car_mask.iff images in the /Tutorial_Misc/masks directory, then
click OK.
2 In the Node View, select the car_bg node.
3 Click the Color tab, and then click Brightness.
A Brightness node is added to the car_bg image.
4 In the Brightness parameters, set the value to .3.
The entire image darkens.