Scaling a movie up – Adobe After Effects CS3 User Manual

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AFTER EFFECTS CS3

User Guide

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Crop to a region of interest

To render just a portion of the composition frame, define a region of interest in the

Composition panel. Then, select the Region Of Interest option in the Output Module Settings dialog box before
rendering. (See “Work with the region of interest” on page 111.)

Note: Cropping an odd number of pixels from the top of a field-rendered movie reverses the field order. For example, if
you crop one row of pixels from the top of a movie with Upper Field First field rendering, the field-rendering order then
becomes Lower Field First. Remember that if you crop pixels from the top of the movie, you need to add to the bottom
row of the movie to maintain the original size. If you are willing to lose one scan line, this gives you a way to output two
movies from one render, each with a different field order.

Render the composition at a reduced resolution

This is the fastest method to create reduced-size movies. For

example, if you create a 640 x 480 composition, you can set the composition resolution to one half, reducing the size
of the rendered composition to 320 x 240. You can then create movies or images at this size. Note that the reduced
resolution reduces the sharpness of the image and is best used for creating preview or draft movies.

Note: When rendering at reduced resolution, set the quality of the composition to Draft. Rendering at Best quality while
reducing resolution does not produce a clean image and takes longer to render than rendering at Draft quality.

“Work in the Render Queue panel” on page 591

Scaling a movie up

Increasing the size of the output from a rendered composition reduces the image quality of a movie and is not recom-
mended. If you must enlarge a movie, to maintain highest image quality, enlarge a composition that was rendered at
full resolution and highest quality using one of the following methods:

Nest the composition

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 compo-
sition to fit the new larger composition size, and then collapse transformations by choosing Layers > Switches >
Collapse. The resulting composition 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 composition

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 composition

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.