anwtfilterfloatlift9x7.java

jpeg2000编解码

            highSig[hk] = inSig[ik]*2;
        }
        
        ik += iStep;   
        hk += highStep;
        
        //Apply first lifting step to each "inner" sample
        for( i = 2 ; i < inLen-1 ; i += 2 ) {           
            highSig[hk] = inSig[ik] + 
                ALPHA*(inSig[ik-inStep] + inSig[ik+inStep]);
            ik += iStep;   
            hk += highStep;
        }

        //If input signal has odd length then we perform the lifting step
        // i.e. apply a symmetric extension.
        if( (inLen%2==1) && (inLen>1) ) {
            highSig[hk] = inSig[ik] + 2*ALPHA*inSig[ik-inStep];
        }
           
        // Generate intermediate low frequency subband
        
        //Initialize counters
        //ik = inOff + inStep;
        ik = inOff + inStep;
        lk = lowOff;
        hk = highOff;
 
        //Apply lifting step to each "inner" sample
        // we are at the component boundary
        for(i = 1; i < inLen-1; i += 2) {
            lowSig[lk] = inSig[ik] + 
                BETA*(highSig[hk] + highSig[hk+highStep]);

            ik += iStep;
            lk += lowStep;  
            hk += highStep;
        }
        if ( inLen>1 && inLen%2==0 ) {
            // symetric extension
            lowSig[lk] = inSig[ik]+2*BETA*highSig[hk];
        }
        
        // Generate high frequency subband
         
        //Initialize counters
        lk = lowOff;
        hk = highOff;

        if ( inLen>1 ) {
            // symmetric extension.
            highSig[hk] += GAMMA*2*lowSig[lk];
        }
        //lk += lowStep;   
        hk += highStep;
        
        //Apply first lifting step to each "inner" sample
        for(i = 2 ; i < inLen-1 ; i += 2)  { 
            highSig[hk] += GAMMA*(lowSig[lk] + lowSig[lk+lowStep]);
            lk += lowStep;   
            hk += highStep;
        }

        //Handle head boundary effect
        if ( inLen>1 && inLen%2==1 ) {
            // symmetric extension.
            highSig[hk] += GAMMA*2*lowSig[lk];
        }

        // Generate low frequency subband
        
        //Initialize counters
        lk = lowOff;
        hk = highOff;
        
        // we are at the component boundary
        for(i = 1 ; i < inLen-1; i += 2) {
            lowSig[lk] += DELTA*(highSig[hk] + highSig[hk+highStep]);
            lk += lowStep;  
            hk += highStep;
        }
        
        if ( inLen>1 && inLen%2==0 ) {
            lowSig[lk] += DELTA*2*highSig[hk];
        }

        // Normalize low and high frequency subbands
         
        //Re-initialize counters
        lk = lowOff;
        hk = highOff;
         
        //Normalize each sample
        for( i=0 ; i<(inLen>>1); i++ ) {
            lowSig[lk] *= KL;
            highSig[hk] *= KH;
            lk += lowStep;  
            hk += highStep;
        }        
        //If the input signal has odd length then normalize the last high-pass
        //coefficient (if input signal is length one filter is identity)
        if( inLen%2==1 && inLen != 1) {
            highSig[hk] *= KH;
        }
    }
    
    /**
     * 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 time-reversed low-pass synthesis waveform of the
     * filter, which is the low-pass filter. This is the time-reversed
     * impulse response of the low-pass synthesis filter. It is used
     * to calculate the L2-norm of the synthesis basis functions for a
     * particular subband (also called energy weight).
     *
     * <P>The returned array may not be modified (i.e. a reference to
     * the internal array may be returned by the implementation of
     * this method).
     *
     * @return The time-reversed low-pass synthesis waveform of the
     * filter.
     * */
    public float[] getLPSynthesisFilter() {
        return LPSynthesisFilter;
    }

    /**
     * Returns the time-reversed high-pass synthesis waveform of the
     * filter, which is the high-pass filter. This is the
     * time-reversed impulse response of the high-pass synthesis
     * filter. It is used to calculate the L2-norm of the synthesis
     * basis functions for a particular subband (also called energy
     * weight).
     *
     * <P>The returned array may not be modified (i.e. a reference to
     * the internal array may be returned by the implementation of
     * this method).
     *
     * @return The time-reversed high-pass synthesis waveform of the
     * filter.
     * */
    public float[] getHPSynthesisFilter() {
        return HPSynthesisFilter;
    }

    /**
     * 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 >= 4 && headOvrlp >= 3 ) return true;
            else return false;
        }
        //Else if the input signal has odd length.
        else {
            if( tailOvrlp >= 4 && headOvrlp >= 4 ) return true;
            else return false;
        }
    }

    /**
     * Tests if the 'obj' object is the same filter as this one. Two filters
     * are the same if the same filter code should be output for both filters
     * by the encodeFilterCode() method.
     *
     * <P>Currently the implementation of this method only tests if 'obj' is
     * also of the class AnWTFilterFloatLift9x7
     *
     * @param The object against which to test inequality.
     * */
    public boolean equals(Object obj) {
        // To spped up test, first test for reference equality
        return obj == this ||
            obj instanceof AnWTFilterFloatLift9x7;
    }

    /** 
     * Returns the type of filter used according to the FilterTypes
     * interface(W9x7).
     *
     * @see FilterTypes
     *
     * @return The filter type.
     * */
    public int getFilterType(){
        return FilterTypes.W9X7;
    } 

    /** Debugging method */
    public String toString(){
	return "w9x7";
    }
}