图像时频变换实例，包括FFT变换、FFT逆变换、DCT变换、DCT逆变换、DWT变换、DWT逆变换、WHT变换、WHT逆变换等。-Examples of image frequency conversion, including FFT transform, FFT transform, DCT transform, DCT transform, DWT transform, DWT transform, WHT transform, inverse transform, etc..