A multiplication-free approximate algorithm for the inverse discrete cosine transform

A fast multiplication-free algorithm for the inverse discrete cosine transform (IDCT) is developed. This algorithm is an approximation to the IDCT and is applicable in implementations of compression standards such as JPEG, MPEG-1, MPEG-2 H.263. The proposed algorithm is 32% faster than its exact counterpart. For low bit-rate video codecs, the quantization effects introduced by the multiplier-free approach is considerably lower than the distortion introduced by the quantizer settings of the video codec and thus the overall PSNR loss is well within 1 dB for the proposed multiplier-free approach. If DCT data sparseness is taken into account, compared with other recently developed fast approximate DCT and IDCT methods, the proposed scheme provides significant reductions in computation complexity. The approach described here can be easily adapted for the forward DCT.