The fundamental image representation used for virtually all of our video processing is the image pyramid. The image pyramid is a representation that separates an original image at full resolution into a set of images that represent the original image at differing spatial resolutions.
Pyramids can represent an image in several different ways.
A pyramid of band-pass images can decompose any image from high to low frequency to permit more efficient searching. A pyramid of difference images can decompose an image to highlight edge information at different resolutions. Pyramids can be used to reconstruct the original image, even without loss of information. Pyramids can have the additional property of not being redundant, and are therefore popular as a basis representation for video compression. The power of the pyramid representation is that it is computationally efficient to generate, and that pyramid-based operations are much faster than the same operations on the original image.