User Guide

CHAPTER 12
386
Rendering a Movie
Making a movie larger than the rendered composition
Increasing the size of the output from a rendered composition reduces the image quality
of a movie and is not recommended. If you must enlarge a movie, to maintain highest
image quality, always enlarge a composition that was rendered at full resolution and
highest quality.
You can create a movie larger than the rendered composition using these methods:
• Create a new composition at the larger dimensions and nest the smaller composition
inside it. For example, if you create a 320 x 240 composition, you can place it in a 640 x
480 composition. Stretch the composition to fit the new larger composition size, and then
collapse transformations by choosing Layers > Switches > Collapse. The resulting compo-
sition rendered at full resolution and best quality will have better image quality than if you
had stretched the movie. However, this method also renders slower than if you created a
composition and stretched it.
Note: To create a draft movie with specific dimensions, use both the Stretch option and
reduced resolution in the rendered composition.
• Stretch the movie. For example, if you create a 320 x 240 composition and render it at
full resolution, you can set the stretch value in the Output Module Settings dialog box to
200% to create a 640 x 480 movie. For a composition rendered at full resolution, the image
quality will usually be acceptable.
Note: Do not use stretching to change the vertical dimensions of a movie with field rendering.
Stretching vertically mixes the field order, which distorts any motion. Use either cropping or
composition nesting if you need to vertically resize a field-rendered movie.
• Crop the movie. To enlarge a movie by a few pixels, increase the size using negative
values for the Crop options in the Output Module Settings dialog box. For example, to
increase the size of a movie by 2 pixels, type –2 in the Cropping section of the Output
Module Settings dialog box. Remember that negative cropping adds to one side of a
movie, so objects originally centered in the composition may not appear centered when
the movie is cropped.
Note: Adding an odd number of pixels to the top of a field-rendered movie reverses the field
order. For example, if you add one row of pixels to the top of a movie with Upper Field First
field rendering, the field-rendering order then becomes Lower Field First. Remember that if
you add pixels to the top of the movie, you need to crop from the bottom row of the movie to
maintain the original size. See “Using interlaced video in After Effects” on page 85 and “Field-
rendering considerations” on page 360.
UG.book Page 386 Wednesday, February 21, 2001 12:05 PM