?? synwtfilterfloatlift9x7.java
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int i; int outLen = lowLen + highLen; //Length of the output signal int iStep = 2*outStep; //Upsampling in outSig int ik; //Indexing outSig int lk; //Indexing lowSig int hk; //Indexing highSig // Initialize counters lk = lowOff; hk = highOff; if(outLen!=1) { int outLen2 = outLen>>1; // "Inverse normalize" each sample for(i=0; i<outLen2; i++) { lowSig[lk] /= KL; highSig[hk] /= KH; lk += lowStep; hk += highStep; } // "Inverse normalise" last high pass coefficient if(outLen%2==1) { highSig[hk] /= KH; } } else { // Normalize for Nyquist gain highSig[highOff] /= 2; } // Generate intermediate low frequency subband //Initialize counters lk = lowOff; hk = highOff; ik = outOff + outStep; //Apply lifting step to each "inner" sample for(i=1; i<outLen-1; i+=2 ) { outSig[ik] = lowSig[lk] - DELTA*(highSig[hk] + highSig[hk+highStep]); ik += iStep; lk += lowStep; hk += highStep; } if(outLen%2==0 && outLen>1) { //Use symmetric extension outSig[ik] = lowSig[lk] - 2*DELTA*highSig[hk]; } // Generate intermediate high frequency subband //Initialize counters hk = highOff; ik = outOff; if(outLen>1) { outSig[ik] = highSig[hk] - 2*GAMMA*outSig[ik+outStep]; } else { outSig[ik] = highSig[hk]; } ik += iStep; hk += highStep; //Apply lifting step to each "inner" sample for(i=2; i<outLen-1; i+=2 ) { outSig[ik] = highSig[hk] - GAMMA*(outSig[ik-outStep] + outSig[ik+outStep]); ik += iStep; hk += highStep; } //Handle head boundary effect if output signal has even length if(outLen%2==1 && outLen>1) { //Use symmetric extension outSig[ik] = highSig[hk] - 2*GAMMA*outSig[ik-outStep]; } // Generate even samples (inverse low-pass filter) //Initialize counters ik = outOff + outStep; //Apply lifting step to each "inner" sample for(i=1; i<outLen-1; i+=2 ) { outSig[ik] -= BETA*(outSig[ik-outStep] + outSig[ik+outStep]); ik += iStep; } if(outLen%2==0 && outLen>1) { // symmetric extension. outSig[ik] -= 2*BETA*outSig[ik-outStep]; } // Generate odd samples (inverse high pass-filter) //Initialize counters ik = outOff; if(outLen>1) { // symmetric extension. outSig[ik] -= 2*ALPHA*outSig[ik+outStep]; } ik += iStep; //Apply first lifting step to each "inner" sample for(i=2; i<outLen-1 ; i+=2) { outSig[ik] -= ALPHA*(outSig[ik-outStep] + outSig[ik+outStep]); ik += iStep; } //Handle head boundary effect if input signal has even length if((outLen%2==1) && (outLen>1)) { //Use symmetric extension outSig[ik] -= 2*ALPHA*outSig[ik-outStep]; } } /** * Returns the negative support of the low-pass analysis filter. That is * the number of taps of the filter in the negative direction. * * @return 2 * */ public int getAnLowNegSupport() { return 4; } /** * Returns the positive support of the low-pass analysis filter. That is * the number of taps of the filter in the negative direction. * * @return The number of taps of the low-pass analysis filter in the * positive direction * */ public int getAnLowPosSupport() { return 4; } /** * Returns the negative support of the high-pass analysis filter. That is * the number of taps of the filter in the negative direction. * * @return The number of taps of the high-pass analysis filter in * the negative direction * */ public int getAnHighNegSupport() { return 3; } /** * Returns the positive support of the high-pass analysis filter. That is * the number of taps of the filter in the negative direction. * * @return The number of taps of the high-pass analysis filter in the * positive direction * */ public int getAnHighPosSupport() { return 3; } /** * Returns the negative support of the low-pass synthesis filter. That is * the number of taps of the filter in the negative direction. * * <P>A MORE PRECISE DEFINITION IS NEEDED * * @return The number of taps of the low-pass synthesis filter in the * negative direction * */ public int getSynLowNegSupport() { return 3; } /** * Returns the positive support of the low-pass synthesis filter. That is * the number of taps of the filter in the negative direction. * * <P>A MORE PRECISE DEFINITION IS NEEDED * * @return The number of taps of the low-pass synthesis filter in the * positive direction * */ public int getSynLowPosSupport() { return 3; } /** * Returns the negative support of the high-pass synthesis filter. That is * the number of taps of the filter in the negative direction. * * <P>A MORE PRECISE DEFINITION IS NEEDED * * @return The number of taps of the high-pass synthesis filter in the * negative direction * */ public int getSynHighNegSupport() { return 4; } /** * Returns the positive support of the high-pass synthesis filter. That is * the number of taps of the filter in the negative direction. * * <P>A MORE PRECISE DEFINITION IS NEEDED * * @return The number of taps of the high-pass synthesis filter in the * positive direction * */ public int getSynHighPosSupport() { return 4; } /** * Returns the implementation type of this filter, as defined in this * class, such as WT_FILTER_INT_LIFT, WT_FILTER_FLOAT_LIFT, * WT_FILTER_FLOAT_CONVOL. * * @return WT_FILTER_INT_LIFT. * */ public int getImplType() { return WT_FILTER_FLOAT_LIFT; } /** * Returns the reversibility of the filter. A filter is considered * reversible if it is suitable for lossless coding. * * @return true since the 9x7 is reversible, provided the appropriate * rounding is performed. * */ public boolean isReversible() { return false; } /** * Returns true if the wavelet filter computes or uses the * same "inner" subband coefficient as the full frame wavelet transform, * and false otherwise. In particular, for block based transforms with * reduced overlap, this method should return false. The term "inner" * indicates that this applies only with respect to the coefficient that * are not affected by image boundaries processings such as symmetric * extension, since there is not reference method for this. * * <P>The result depends on the length of the allowed overlap when * compared to the overlap required by the wavelet filter. It also * depends on how overlap processing is implemented in the wavelet * filter. * * @param tailOvrlp This is the number of samples in the input * signal before the first sample to filter that can be used for * overlap. * * @param headOvrlp This is the number of samples in the input * signal after the last sample to filter that can be used for * overlap. * * @param inLen This is the lenght of the input signal to filter.The * required number of samples in the input signal after the last sample * depends on the length of the input signal. * * @return true if both overlaps are greater than 2, and correct * processing is applied in the analyze() method. * * * */ public boolean isSameAsFullWT(int tailOvrlp, int headOvrlp, int inLen) { //If the input signal has even length. if(inLen % 2 == 0) { if(tailOvrlp >= 2 && headOvrlp >= 1) return true; else return false; } //Else if the input signal has odd length. else { if(tailOvrlp >= 2 && headOvrlp >= 2) return true; else return false; } } /** * Returns a string of information about the synthesis wavelet filter * * @return wavelet filter type. * * */ public String toString(){ return "w9x7 (lifting)"; }}
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