中文说明： 小波变换的绝对值大的小波系数，对应着显著的亮度变化，也就是图像中的显著特征。所以，选择绝对值大 的小波系数作为我们需要的小波系数。【注意，前面取的是绝对值大小，而不是实际数值大小】
English Description：
&The wavelet coefficients with large absolute value of wavelet transform correspond to significant brightness changes, that is, significant features in the image. Therefore, we choose the wavelet coefficients with large absolute value as the wavelet coefficients we need. [note that the absolute value is taken before, not the actual value] & nbsp;