基于小波变换的快速矢量量化(VQ)编码

A Fast Vector Quantification Image Coding Scheme Based on Wavelet Transform

信源大多存在相关性,即使对无记忆的信源来说,矢量量化编码相对于标量量化来说能够得到更好的效果.但是纯粹的矢量编码后得到的图像,压缩比高时图像失真也高,而且对于整幅图像都采用相同的矢量量化,收敛速度也慢.采用先对图像进行小波变换,然后对低频分量分配较少的压缩位,减少图像失真,而高频分量分配较多的压缩位,达到较高的压缩比.在进行矢量量化编码时采用了一种快速算法,加快了编码的速度.

Compared with Scalar Quantification, Vector Quantification can get better effect in digital signal quantification especially in image processing. Using VQ in image compression can only get small compression ratio if you want to get good quality of image. It also costs more time if you use the same method in whole image. The paper proposes using wavelet transform before VQ in image processing. The coefficients of image working on the highs of image were reserved accurately, but the coefficients of image working on the lows of image were quantified roughly. The results show that this method can get satisfying quality and high compression ratio.