Graphics Programs Reference
In-Depth Information
By default, the ShuffleCopy node is set to copy the alpha channel from the selec-
ted channel set in input 1 and the RGB from the selected channel set in input 2,
which is what you're after.
Since you started this exercise by unpremultiplying all the passes, it's time to
premultiply again now that you have a correct alpha channel.
4. Select ShuffleCopy1 and connect a Premult node after it.
5. View Premult1 in the Viewer. Make sure to display the last frame.
You have now rebuilt the beauty pass with the correct alpha. You also ensured
thatyouhaveeasyaccesstoallthevariouspassesforeasymanipulation( FIGURE
3.40 ) .
Figure 3.40. The beauty pass, premultiplied.
Manipulating Passes
Now, by playing with the various branches, you can change the colors of elements that
makeupthelemmingimage—suchastheamountoflightfallingontheobject,howbright
or sharp the specular highlights are, and so forth.
Let'sstartbychangingthecoloroftheIncidencepass.Youwantittobeaslightlybrighter
version of the fur color instead of the gray color it is now.
 
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