Adobe After Effects CS4 - Manual (Page 312)

306 USING AFTER EFFECTS CS4
Drawing, painting, and paths
Last updated 12/21/2009
After Effects interpolates a paint stroke (center) between two different shapes created with the same brush (left and right).
Overview of shape layers, paths, and vector graphics
About vector graphics and raster images
Vector graphics are made up of lines and curves defined by mathematical objects called vectors, which describe an
image according to its geometric characteristics. Examples of vector graphics elements within After Effects include
mask paths, shapes on shape layers, and text on text layers.
Raster images (sometimes called bitmap images) use a rectangular grid of picture elements (pixels) to represent images.
Each pixel is assigned a specific location and color value. Video footage, image sequences transferred from film, and
many other types of images imported into After Effects are raster images.
Vector graphics maintain crisp edges and lose no detail when resized, because they are resolution-independent. This
resolution-independence makes vector graphics a good choice for visual elements, such as logos, that will be used at
various sizes.
Example of a vector graphic at different levels of magnification
Raster images each consist of a fixed number of pixels, and are therefore resolution-dependent. Raster images can lose
detail and appear jagged (pixelated) if they are scaled up.
Example of a raster image at different levels of magnification
Some images are created as vector graphics in another application but are converted to pixels (rasterized) when they
are imported into After Effects. If a layer is continuously rasterized, After Effects reconverts the vector graphics to
pixels when the layer is resized, preserving sharp edges. Vector graphics from SWF, PDF, EPS, and Illustrator files can
be continuously rasterized.
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