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 具體地,結(jié)合指紋圖像中高頻豐富的特點(diǎn),以及小波包高頻分辨率高的分析特性,選用小波包對指紋圖像進(jìn)行初濾波;在設(shè)計(jì)方向?yàn)V波器時(shí),對濾波器的旋轉(zhuǎn)引入了方?圓變換的方法,進(jìn)而減少了計(jì)算的復(fù)雜度,同時(shí)避免引入誤差。