  A new class of matrices based on a parametrization of the Feig-Winograd
factorization of 8-point DCT is proposed. Such parametrization induces a matrix
subspace, which unifies a number of existing methods for DCT approximation. By
solving a comprehensive multicriteria optimization problem, we identified
several new DCT approximations. Obtained solutions were sought to possess the
following properties: (i) low multiplierless computational complexity, (ii)
orthogonality or near orthogonality, (iii) low complexity invertibility, and
(iv) close proximity and performance to the exact DCT. Proposed approximations
were submitted to assessment in terms of proximity to the DCT, coding
performance, and suitability for image compression. Considering Pareto
efficiency, particular new proposed approximations could outperform various
existing methods archived in literature.
