频域法加入数字水印的原理是首先将原始信号（语音一维信号、图像二维信号）变换到频域，常用的变换一般有DWT、DCT、DFT、WP和分形。然后，对加入了水印信息的信号进行频域反变换（IDWT、IDCT、DFT、WP），得到含有水印信息的信号。-Frequency-domain digital watermarking method by adding the principle is that first of all, the original signal (voice signal of one-dimensional, two-dimensional image signal) to frequency domain transformation, commonly used in general transform DWT, DCT, DFT, WP and fractal. Then, adding the watermark information signal to the frequency domain inverse transform (IDWT, IDCT, DFT, WP), received signal containing the watermark information.