Functions are mappings from one Manifold to another. Discrete Functions are functions which can be represented using a finite number of values. Given the finite extent of computer memory, algorithms which compute a function that satisfies some special properties are computing a discrete function which approximates a continuous function. Computing the function involves writing a set of equations that may be solved for the values representing the function.
Abstract—The contourlet transform is a new two-dimensional
extension of the wavelet transform using multiscale and direc-
tional fi lter banks. The contourlet expansion is composed of
basis images oriented at various directions in multiple scales,
with fl exible aspect ratios. Given this rich set of basis images,
the contourlet transform effectively captures smooth contours
that are the dominant feature in natural images.
