The technique of pre-scaled integer transform

Abstract

The integer cosine transform (ICT) is adopted by H.264/AVC for its bit-exact implementation and significant complexity reduction compared to the discrete cosine transform (DCT) with an impact in peak signal-to-noise ratio (PSNR) of less than 0.02dB. In this paper, a new technique, named pre-scaled integer transform (PIT), is proposed. With PIT, the implementation complexity is further reduced compared to conventional ICT, especially for low-end processors while all the merits of ICT are kept. Extensive experiments show that no obvious penalty in performance is observed but rather a slight gain in PSNR is obtained by using PIT when the integer transform matrix used meets certain requirements.