Novel full-search schemes for speeding up image coding using vector quantization

The routine for finding the closest codeword in the encoding phase of vector quantization (VQ) is high computational complexity and time consuming, especially when the codewords deal with the high-dimensional vectors. In this paper, we propose three newly developed schemes for speeding up the encoding phase of VQ. The proposed schemes can easily filter out many impossible codewords such that the search domain is reduced. The experimental results show that the computational time of our proposed schemes can save more than 41–52% computational time in a full search scheme. Furthermore, our schemes only require fewer than 84% of the computational time required in recently proposed alternative.