Scaling a movie up

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, 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 320x240 composition, you can place it in a 640x480 composition. Stretch the composition 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 320x240 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 640x480 movie. For a composition rendered at full resolution, the image quality is usually 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, enter –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.

Adobe Photoshop provides fine control over resampling methods used for scaling of images. For fine control of resampling, you can export frames to Photoshop to change the image size and then import the frames back into After Effects.

For a list of plug-ins that provide high-quality scaling—including some designed to create high-definition images from standard-definition sources—see the Toolfarm website.

For a script that scales multiple compositions simultaneously, see the AE Enhancers forum.