传统的图像分辨率降低主要是通过图像重采样实现的。多进制小波是近年来发展的小波分析理论的一个新的分支,它在正交性、紧支性、光滑性方面都优于二进制小波。本文首先介绍图像分辨率定量降低的需求与传统的图像分辨率降低方法;然后,以多进制小波的时频多分辨率特性,把多进制小波变换应用于定量降低图像分辨率,并用三进制小波变换进行了图像分辨率降低实验,提取三进制小波的低频分量作为降低分辨率后的图像;最后,通过与常用的图像重采样方法,如最临近法、双线性插值法及其衍生的邻域平均法的结果进行定性与定量评价,结果表明多进制小波在图像分辨率定量降低方面具有明显的优势。

The achievement of traditional image resolution reduction is primarily through image resampling. Multi-band wavelet is a newly developed branch of wavelet analysis, and its orthogonality, compact support and smoothness are better than the binary wavelet. In this paper we firstly described the demand of quantitative reduction of image resolution and the traditional methods on image resolution reduction. Then we used multi-band wavelet to reduce image resolution quantitatively based on multi-resolution time frequency characteristics. We did the image resolution reduction experiment through the 3-band wavelet transformation and extracted the low-frequency information of the 3-band wavelet as the resulting image that achieved the image resolution reduction. Lastly, compared with the results of common image re-sampling methods, such as the nearest method, bilinear interpolation method and derivative neighborhood averaging method qualitatively and quantitatively, we found that multi-band wavelet has obvious advantages in image resolution reduction.