Close approximations of ideal linear transforms, such as the forward and
inverse discrete cosine transformation (DCT), are formed with minimum
complexity using fixed-point arithmetic. The transformation is decomposed
into a smaller set of transformations (e.g., the LLM decomposition of the
DCT). The multiplication factors of the decomposition are then
approximated by a fixed-point representation. However, instead of simply
applying scaling and rounding operations to produce fixed-point
approximations closest to the multiplication factors themselves,
fixed-point multiplication factors are chosen that have the effect (after
the cascaded operations of the various stages of decomposition) of being
the closest feasible approximations of the entries in the resulting
complete ideal transformation matrix.