High Efficiency Video Coding (HEVC) is the next generation video coding standard currently being developed by the Joint Collaborative Team on Video Coding (JCT-VC). It employs various coding unit sizes 2K×2K, where K is a positive integer with the typical values from 3 to 6; it also uses larger transform sizes up to 32×32. This raises the interest in seeking high performance higher order integer transforms with low computation requirements. This paper presents approaches to designing order-N (N=4, 8, 16, 32) integer transforms, by which the derived integer transforms have special symmetry structures to ensure the matrix factorization. The proposed set of high order integer transforms with well selected elements demonstrates excellent coding performance, compared with the core transform design in HEVC.
"Core transform design for high-efficiency video coding", Proc. SPIE 8499, Applications of Digital Image Processing XXXV, 84990T (15 October 2012); doi: 10.1117/12.954129; https://doi.org/10.1117/12.954129