PADDEDSIZE Computes padded sizes useful for FFT-based filtering

通过使用填充和不填充观察其滤波效果！使用了低通滤波器生成一个高斯滤波器！-Fill and not fill through the use of filtering effect observed! Low-pass filter used to generate a Gaussian filter!

求最小二次幂的函数，用于fft补零，有多个功能(The function of the minimum two power is used to replace the FFT zero.)