Apple Shake 4 - Manual (Page 210)

210 Chapter 6 Importing Video and Anamorphic Film
This is a fundamental principle when compositing anamorphically squeezed
elements—the actual image should never actually be scaled, but in order to work on
the image, you still need to see the results as they will look in widescreen. Shake has
specific parameters that allow you to preserve the original anamorphic data, while
viewing the frame at the proper unsqueezed ratio for purposes of layering other
images, rotoscoping, and painting.
Anamorphic Examples
The following screenshot depicts an anamorphic frame. The image resolution is 914 x
778, or half of a standard 1828 x 1556 anamorphic plate. You can see from the shape of
the circle that the image is squeezed along the X axis.
Properly Viewing Squeezed Images
There are two ways to view this image in its unsqueezed, widescreen proportions. You
might be tempted to change the resolution of the image with a Zoom or Resize node,
but this would be the wrong thing to do. Zooming the image horizontally (by the Y
axis) down by 2 (or up by 2 in the X axis), compositing, and then zooming it back to its
squeezed proportions would result in an unacceptable and unnecessary loss of quality.
The correct way to work with an anamorphic image is to modify either the Viewer’s
aspect ratio, or the script’s proxyRatio. The script proxyRatio is better for film elements,
and the Viewer aspect ratio is better for video elements.
• Video: To change the Viewer aspect ratio, expand the format subtree in the Globals
tab and set the defaultViewerAspectRatio parameter to 2 (the anamorphic ratio is 2:1
for this film plate).
For video, use the appropriate ratio, which is listed in the Table of Common Aspect
Ratios at the end of this chapter. Doing this renders the image at full resolution, and
then doubles the Viewer’s width. Because you are modifying only the Viewer
parameters, this has no effect on your output resolution, and images take exactly the
same amount of time to render.