A method and apparatus for efficiently encoding images using a set of
non-orthogonal basis functions, thereby allowing reduction of file size,
shorter transmission time, and improved accuracy. The non-orthogonal basis
functions include homogenous color basis functions, luminance-encoding
basis functions that have luminance edges and chromatic basis functions
that exhibit color opponency. Some of the basis functions are
non-orthogonal with respect to each other. Using these basis functions, a
source vector is calculated to provide a number of coefficients, each
coefficient associated with one basis function. The source vector is
compressed by selecting a subset of the calculated coefficients, thereby
providing an encoded vector. Because the method is highly efficient, the
image data is substantially represented by a small number of coefficients.
In some embodiments, the non-orthogonal basis functions include two or
more classes. A wavelet approach can also be utilized.
