Viewing the number of image channels, Displaying individual channels in the viewer – Apple Shake 4 User Manual
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Chapter 15
Image Processing Basics
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If you apply an operation that changes channel information, Shake automatically
updates which channels are used. For example, if you place a Color–Monochrome or
Filter–Emboss node on an RGB image, that image becomes a BW image at that point,
speeding up the calculation of the subsequent nodes. If you then composite the image
over an RGB image or change its color (for example, via a Mult node with values of 1.01,
1, 1), the BW image becomes an RGB image again.
In certain situations, this behavior may seem nonintuitive. For example, a 3-channel
image composited with an Inside node to a matte image still results in a 3-channel
image—no matte channel is added to the result. This eliminates the need to add an
alpha channel to the 3-channel image just to combine it. If, however, you want to add
or remove channels at some point, you can use the Copy, SwitchMatte, Color–Set, or
Color–Reorder node.
Viewing the Number of Image Channels
There are several ways you can see how many image channels are being used by the
current node.
To determine the number of channels in an image, do one of the following:
m
Load the image into the Viewer, then the look in Viewer title bar display.
m
Position the pointer over the node in the Node View and look at the Info field at the
bottom of the interface.
m
In the Command Line field, type:
shake my_image -info
m
To view the Z channel, use the View Z script button.
For more information on displaying channels in the Viewer, see “
Displaying Individual Channels in the Viewer
If necessary, you can display each individual channel in the Viewer to help you fine-
tune your composite.
To view the alpha channel of an image, do one of the following:
m
Position the pointer in the Viewer (or the Flipbook), then press A.
m
Click the View Channel button, then choose the alpha channel option from the pop-up
menu.