说明：  数学地角度来看，信号与图像处理可以统一看作是信号处理（图像可以看作是二维信号），在小波分析地许多分析的许多应用中，都可以归结为信号处理问题。对于其性质随时间是稳定不变的信号，处理的理想工具仍然是傅立叶分析。但是在实际应用中的绝大多数信号是非稳定的，而特别适用于非稳定信号的工具就是小波分析。
(Mathematically, signal and image processing can be regarded as signal processing (image can be regarded as two-dimensional signal). In many applications of wavelet analysis, they can be reduced to signal processing. For signals whose properties are stable over time, the ideal tool for processing is still Fourier analysis. However, most of the signals in practical applications are unstable, and the tool especially suitable for unstable signals is wavelet analysis.)