FTF快速横向滤波算法，需要对四个横向滤波器－－基本滤波器，前向预测滤波器，后向预测滤波器和增益滤波器的更新。-FTF rapid horizontal filtering algorithm, the need for the four transversal filter- Basic filter, prior to the prediction filter, to the prediction filter and update the filter gain.