# !/bin/env python # -*- coding: latin-1 -*- ##/************************************************** ##* Fichier : FastSymmlet8.py ##* Format : PYTHON ##* ##* (c) 1998-2002 Daniel Lemire, Ph.D. ##* Python translation 2004 Valentin Gies ##* http://www.vgies.com/p=wavelets ##* http://www.ondelette.com/ - wavelet forum - forum sur les ondelettes ##* ##* Last modified on August 19 2004 ##* ##* Free for any use, but this copyright notice must remain. ##* Provide as is. Use at your risks. ##* ##* Gratuit pour toute utilisation, mais préservez cette mention. ##* Sans garantie aucune, utilisez à vos risques. ##* ##* Python implementation of the Symmlet8 wavelet. ##* See end of the file for usage. ##* ##* Cette classe utilise les ondelettes Symmlet8. Son ##* utilisation est très simple (voir la fin du fichier ##* pour un exemple). Elle suppose des conditions périodiques ##* aux bords. ##* ##***************************************************/ import math scale = [0.0322231006040782, -0.0126039672622638, -0.0992195435769564, 0.297857795605605, 0.803738751805386, 0.497618667632563, -0.0296355276459604, -0.0757657147893567] wavelet = [0.0757657147893567, -0.0296355276459604, -0.497618667632563, 0.803738751805386, -0.297857795605605, -0.0992195435769564, 0.0126039672622638, 0.0322231006040782] ##/************************************************ ##* An efficient implementation of ##* the Fast Wavelet Transform using ##* Symmlet8 wavelets (FBI fingerprints standard) ##*************************************************/ class FastSymmlet8: def transform2(self, length, v, last): ans=[0.0 for i in range(last)] half = last/2 for k in range(half-3): ans[k+half]=v[(2*k+0)]*wavelet[0]+v[(2*k+1)]*wavelet[1]+v[(2*k+2)]*wavelet[2]+v[(2*k+3)]*wavelet[3]+v[(2*k+4)]*wavelet[4]+v[(2*k+5)]*wavelet[5]+v[(2*k+6)]*wavelet[6]+v[(2*k+7)]*wavelet[7] ans[k]=v[(2*k+0)]*scale[0]+v[(2*k+1)]*scale[1]+v[(2*k+2)]*scale[2]+v[(2*k+3)]*scale[3]+v[(2*k+4)]*scale[4]+v[(2*k+5)]*scale[5]+v[(2*k+6)]*scale[6]+v[(2*k+7)]*scale[7] ans[last-3]=v[last-6]*wavelet[0]+v[last-5]*wavelet[1]+v[last-4]*wavelet[2]+v[last-3]*wavelet[3]+v[last-2]*wavelet[4]+v[last-1]*wavelet[5]+v[0]*wavelet[6]+v[1]*wavelet[7] ans[half-3]=v[last-6]*scale[0]+v[last-5]*scale[1]+v[last-4]*scale[2]+v[last-3]*scale[3]+v[last-2]*scale[4]+v[last-1]*scale[5]+v[0]*scale[6]+v[1]*scale[7] ans[last-2]=v[last-4]*wavelet[0]+v[last-3]*wavelet[1]+v[last-2]*wavelet[2]+v[last-1]*wavelet[3]+v[0]*wavelet[4]+v[1]*wavelet[5]+v[2]*wavelet[6]+v[3]*wavelet[7] ans[half-2]=v[last-4]*scale[0]+v[last-3]*scale[1]+v[last-2]*scale[2]+v[last-1]*scale[3]+v[0]*scale[4]+v[1]*scale[5]+v[2]*scale[6]+v[3]*scale[7] ans[last-1]=v[last-2]*wavelet[0]+v[last-1]*wavelet[1]+v[0]*wavelet[2]+v[1]*wavelet[3]+v[2]*wavelet[4]+v[3]*wavelet[5]+v[4]*wavelet[6]+v[5]*wavelet[7] ans[half-1]=v[last-2]*scale[0]+v[last-1]*scale[1]+v[0]*scale[2]+v[1]*scale[3]+v[2]*scale[4]+v[3]*scale[5]+v[4]*scale[6]+v[5]*scale[7] for k in range(last): v[k]=ans[k] def transform (self, length, v): last = length while (last>8): self.transform2(length,v,last) last /=2 if(last!=8): print "Attention : n'est pas une puissance de 2 : "+str(length) print "Careful : not a power of 2 : "+str(length) def invTransform2(self, length, v, last): ResultingLength=2*last ans=[0.0 for i in range(ResultingLength)] for k in range(int(math.ceil((ResultingLength-7)/2.0))): ans[(2*k+7)]+=scale[7]*v[k]+wavelet[7]*v[k+last] ans[(2*k+6)]+=scale[6]*v[k]+wavelet[6]*v[k+last] ans[(2*k+5)]+=scale[5]*v[k]+wavelet[5]*v[k+last] ans[(2*k+4)]+=scale[4]*v[k]+wavelet[4]*v[k+last] ans[(2*k+3)]+=scale[3]*v[k]+wavelet[3]*v[k+last] ans[(2*k+2)]+=scale[2]*v[k]+wavelet[2]*v[k+last] ans[(2*k+1)]+=scale[1]*v[k]+wavelet[1]*v[k+last] ans[(2*k+0)]+=scale[0]*v[k]+wavelet[0]*v[k+last] ans[ResultingLength-6]+=scale[0]*v[last-3]+wavelet[0]*v[ResultingLength-3] ans[ResultingLength-5]+=scale[1]*v[last-3]+wavelet[1]*v[ResultingLength-3] ans[ResultingLength-4]+=scale[2]*v[last-3]+wavelet[2]*v[ResultingLength-3] ans[ResultingLength-3]+=scale[3]*v[last-3]+wavelet[3]*v[ResultingLength-3] ans[ResultingLength-2]+=scale[4]*v[last-3]+wavelet[4]*v[ResultingLength-3] ans[ResultingLength-1]+=scale[5]*v[last-3]+wavelet[5]*v[ResultingLength-3] ans[0]+=scale[6]*v[last-3]+wavelet[6]*v[ResultingLength-3] ans[1]+=scale[7]*v[last-3]+wavelet[7]*v[ResultingLength-3] ans[ResultingLength-4]+=scale[0]*v[last-2]+wavelet[0]*v[ResultingLength-2] ans[ResultingLength-3]+=scale[1]*v[last-2]+wavelet[1]*v[ResultingLength-2] ans[ResultingLength-2]+=scale[2]*v[last-2]+wavelet[2]*v[ResultingLength-2] ans[ResultingLength-1]+=scale[3]*v[last-2]+wavelet[3]*v[ResultingLength-2] ans[0]+=scale[4]*v[last-2]+wavelet[4]*v[ResultingLength-2] ans[1]+=scale[5]*v[last-2]+wavelet[5]*v[ResultingLength-2] ans[2]+=scale[6]*v[last-2]+wavelet[6]*v[ResultingLength-2] ans[3]+=scale[7]*v[last-2]+wavelet[7]*v[ResultingLength-2] ans[ResultingLength-2]+=scale[0]*v[last-1]+wavelet[0]*v[ResultingLength-1] ans[ResultingLength-1]+=scale[1]*v[last-1]+wavelet[1]*v[ResultingLength-1] ans[0]+=scale[2]*v[last-1]+wavelet[2]*v[ResultingLength-1] ans[1]+=scale[3]*v[last-1]+wavelet[3]*v[ResultingLength-1] ans[2]+=scale[4]*v[last-1]+wavelet[4]*v[ResultingLength-1] ans[3]+=scale[5]*v[last-1]+wavelet[5]*v[ResultingLength-1] ans[4]+=scale[6]*v[last-1]+wavelet[6]*v[ResultingLength-1] ans[5]+=scale[7]*v[last-1]+wavelet[7]*v[ResultingLength-1] for k in range(ResultingLength): v[k]=ans[k] def invTransform (self, length, v): last = 8 while (2*last <= length): self.invTransform2(length, v, last) last*=2 if(last!=length): print "Attention : n'est pas une puissance de 2 : "+str(length) print "Careful : not a power of 2 : "+str(length) def expand(length, v): last=length/2 ResultingLength=2*last ans=[0.0 for i in range(ResultingLength)] for k in range((ResultingLength-7)/2): ans[ResultingLength-6]+=scale[0]*v[last-3] ans[ResultingLength-5]+=scale[1]*v[last-3] ans[ResultingLength-4]+=scale[2]*v[last-3] ans[ResultingLength-3]+=scale[3]*v[last-3] ans[ResultingLength-2]+=scale[4]*v[last-3] ans[ResultingLength-1]+=scale[5]*v[last-3] ans[0]+=scale[6]*v[last-3] ans[1]+=scale[7]*v[last-3] ans[ResultingLength-4]+=scale[0]*v[last-2] ans[ResultingLength-3]+=scale[1]*v[last-2] ans[ResultingLength-2]+=scale[2]*v[last-2] ans[ResultingLength-1]+=scale[3]*v[last-2] ans[0]+=scale[4]*v[last-2] ans[1]+=scale[5]*v[last-2] ans[2]+=scale[6]*v[last-2] ans[3]+=scale[7]*v[last-2] ans[ResultingLength-2]+=scale[0]*v[last-1] ans[ResultingLength-1]+=scale[1]*v[last-1] ans[0]+=scale[2]*v[last-1] ans[1]+=scale[3]*v[last-1] ans[2]+=scale[4]*v[last-1] ans[3]+=scale[5]*v[last-1] ans[4]+=scale[6]*v[last-1] ans[5]+=scale[7]*v[last-1] for k in range(length): v[k]=ans[k] #Test du programme : t est l'echantillon a analyser t=[1.0,1.0,1.0,1.0, 1.0,1.0,1.0,1.0, 0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0, 1.0,1.0,1.0,1.0, 1.0,1.0,1.0,1.0, 0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0] length = len(t) Ondelette = FastSymmlet8() Ondelette.transform(length,t) Ondelette.invTransform(length,t) print t