Because the high resolution on high frequency of wavelet package meets the feature of fingerprint containing abundant high frequency , we filtered the fingerprint preliminarily by means of wavelet package . while designing orientation filter , we introduced the square - circle transform to rotate filter , thus we reduced computing complexity and avoided imported errors 具体地,结合指纹图像中高频丰富的特点,以及小波包高频分辨率高的分析特性,选用小波包对指纹图像进行初滤波;在设计方向滤波器时,对滤波器的旋转引入了方?圆变换的方法,进而减少了计算的复杂度,同时避免引入误差。