The effect of the block directional-based binary method for fingerprint image is mainly determined by the estimate accuracy of the block direction.

基于块方向信息的指纹图像二值化方法，其效果主要取决于能否准确的估计指纹图像的块方向图。

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So the block direction obtained by this method can correspond to the tendency of the lines in the whole image precisely.

针对该方法得到的块方向图会出现奇异点漂移的现象，使用一种低通滤波的办法来修正块方向图。

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