After Effects Chromatic Aberration

Chromatic aberration effects, done with After Effects CS5.5 without external plugin or footages.
The adjustable settings are:
Power: the chromatic aberration value
Scale compensation: automatic scale compensation to perfecly fit the image in the comp area.

Definition of chromatic aberration:
In optics, chromatic aberration (CA, also called achromatism or chromatic distortion) is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light (the dispersion of the lens). The refractive index decreases with increasing wavelength.
Chromatic aberration manifests itself as “fringes” of color along boundaries that separate dark and bright parts of the image, because each color in the optical spectrum cannot be focused at a single common point. Since the focal length f of a lens is dependent on the refractive index n, different wavelengths of light will be focused on different positions.