/*
 * $RCSfile: AnWTFilterFloatLift9x7.java,v $
 * $Revision: 1.1 $
 * $Date: 2005/02/11 05:02:29 $
 * $State: Exp $
 *
 * Class:                   AnWTFilterFloatLift9x7
 *
 * Description:             An analyzing wavelet filter implementing the
 *                          lifting 9x7 transform.
 *
 *
 *
 * COPYRIGHT:
 *
 * This software module was originally developed by Raphaël Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 *
 * Copyright (c) 1999/2000 JJ2000 Partners.
 * */
package jj2000.j2k.wavelet.analysis;

import jj2000.j2k.wavelet.FilterTypes;

/**
 * This class inherits from the analysis wavelet filter definition
 * for int data. It implements the forward wavelet transform
 * specifically for the 9x7 filter. The implementation is based on
 * the lifting scheme.
 *
 * <P>See the AnWTFilter class for details such as
 * normalization, how to split odd-length signals, etc. In particular,
 * this method assumes that the low-pass coefficient is computed first.
 *
 * @see AnWTFilter
 * @see AnWTFilterFloat
 * */
public class AnWTFilterFloatLift9x7 extends AnWTFilterFloat {

    /** The low-pass synthesis filter of the 9x7 wavelet transform */
    private final static float LPSynthesisFilter[] =
    { -0.091272f, -0.057544f, 0.591272f, 1.115087f,
      0.591272f, -0.057544f, -0.091272f};

    /** The high-pass synthesis filter of the 9x7 wavelet transform */
    private final static float HPSynthesisFilter[] =
        { 0.026749f, 0.016864f, -0.078223f, -0.266864f,
          0.602949f,
          -0.266864f, -0.078223f, 0.016864f, 0.026749f };

    /** The value of the first lifting step coefficient */
    public final static float ALPHA = -1.586134342f;

    /** The value of the second lifting step coefficient */
    public final static float BETA = -0.05298011854f;

    /** The value of the third lifting step coefficient */
    public final static float GAMMA = 0.8829110762f;

    /** The value of the fourth lifting step coefficient */
    public final static float DELTA = 0.443568522f;

    /** The value of the low-pass subband normalization factor */
    public final static float KL = 0.8128930655f;//1.149604398f;

    /** The value of the high-pass subband normalization factor */
    public final static float KH = 1.230174106f;//0.8698644523f;

    /**
     * An implementation of the analyze_lpf() method that works on int
     * data, for the forward 9x7 wavelet transform using the
     * lifting scheme. See the general description of the analyze_lpf()
     * method in the AnWTFilter class for more details.
     *
     * <P>The coefficients of the first lifting step are [ALPHA 1 ALPHA].
     *
     * <P>The coefficients of the second lifting step are [BETA 1 BETA].
     *
     * <P>The coefficients of the third lifting step are [GAMMA 1 GAMMA].
     *
     * <P>The coefficients of the fourth lifting step are [DELTA 1 DELTA].
     *
     * <P>The low-pass and high-pass subbands are normalized by respectively
     * a factor of KL and a factor of KH
     *
     * @param inSig This is the array that contains the input
     * signal.
     *
     * @param inOff This is the index in inSig of the first sample to
     * filter.
     *
     * @param inLen This is the number of samples in the input signal
     * to filter.
     *
     * @param inStep This is the step, or interleave factor, of the
     * input signal samples in the inSig array.
     *
     * @param lowSig This is the array where the low-pass output
     * signal is placed.
     *
     * @param lowOff This is the index in lowSig of the element where
     * to put the first low-pass output sample.
     *
     * @param lowStep This is the step, or interleave factor, of the
     * low-pass output samples in the lowSig array.
     *
     * @param highSig This is the array where the high-pass output
     * signal is placed.
     *
     * @param highOff This is the index in highSig of the element where
     * to put the first high-pass output sample.
     *
     * @param highStep This is the step, or interleave factor, of the
     * high-pass output samples in the highSig array.
     * */
    public
        void analyze_lpf(float inSig[], int inOff, int inLen, int inStep,
                     float lowSig[], int lowOff, int lowStep,
                     float highSig[], int highOff, int highStep) {
        int i,maxi;
        int iStep = 2 * inStep; //Subsampling in inSig
        int ik;    //Indexing inSig
        int lk;    //Indexing lowSig
        int hk;    //Indexing highSig

        // Generate intermediate high frequency subband

        //Initialize counters
        ik = inOff + inStep;
        lk = lowOff;
        hk = highOff;

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

            ik += iStep;
            hk += highStep;
        }

        //Handle head boundary effect if input signal has even length
        if(inLen % 2 == 0) {
           highSig[hk] = inSig[ik] + 2*ALPHA*inSig[ik-inStep];
        }

        // Generate intermediate low frequency subband

        //Initialize counters
        ik = inOff;
        lk = lowOff;
        hk = highOff;

        if(inLen>1) {
            lowSig[lk] = inSig[ik] + 2*BETA*highSig[hk];
        }
        else {
            lowSig[lk] = inSig[ik];
        }

        ik += iStep;
        lk += lowStep;
        hk += highStep;

        //Apply lifting step to each "inner" sample
        for( i = 2, maxi = inLen-1; i < maxi; i += 2 ) {
            lowSig[lk] = inSig[ik] +
                BETA*(highSig[hk-highStep] + highSig[hk]);

            ik += iStep;
            lk += lowStep;
            hk += highStep;
        }

        //Handle head boundary effect if input signal has odd length
        if((inLen % 2 == 1)&&(inLen>2)) {
            lowSig[lk] =  inSig[ik] + 2*BETA*highSig[hk-highStep];
        }

        // Generate high frequency subband

        //Initialize counters
        lk = lowOff;
        hk = highOff;

        //Apply first lifting step to each "inner" sample
        for(i = 1, maxi = inLen-1; i < maxi; i += 2)  {
            highSig[hk] += GAMMA*(lowSig[lk] + lowSig[lk+lowStep]);

            lk += lowStep;
            hk += highStep;
        }

        //Handle head boundary effect if input signal has even length
        if(inLen % 2 == 0) {
            highSig[hk] += 2*GAMMA*lowSig[lk];
        }

        // Generate low frequency subband

        //Initialize counters
        lk = lowOff;
        hk = highOff;

        //Handle tail boundary effect
        //If access the overlap then perform the lifting step
        if(inLen>1){
            lowSig[lk] += 2*DELTA*highSig[hk];
        }

        lk += lowStep;
        hk += highStep;

        //Apply lifting step to each "inner" sample
        for(i = 2, maxi = inLen-1; i < maxi; i += 2) {
            lowSig[lk] +=
                DELTA*(highSig[hk - highStep] + highSig[hk]);

            lk += lowStep;
            hk += highStep;
        }

        //Handle head boundary effect if input signal has odd length
        if((inLen % 2 == 1)&&(inLen>2)) {
            lowSig[lk] +=  2*DELTA*highSig[hk-highStep];
        }

        // 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 low-pass
        //coefficient (if input signal is length one filter is identity)
        if( inLen%2==1 && inLen != 1) {
            lowSig[lk] *= KL;
        }
    }

    /**
     * An implementation of the analyze_hpf() method that works on int
     * data, for the forward 9x7 wavelet transform using the
     * lifting scheme. See the general description of the analyze_hpf() method
     * in the AnWTFilter class for more details.
     *
     * <P>The coefficients of the first lifting step are [ALPHA 1 ALPHA].
     *
     * <P>The coefficients of the second lifting step are [BETA 1 BETA].
     *
     * <P>The coefficients of the third lifting step are [GAMMA 1 GAMMA].
     *
     * <P>The coefficients of the fourth lifting step are [DELTA 1 DELTA].
     *
     * <P>The low-pass and high-pass subbands are normalized by respectively
     * a factor of KL and a factor of KH
     *
     * @param inSig This is the array that contains the input
     * signal.
     *
     * @param inOff This is the index in inSig of the first sample to
     * filter.
     *
     * @param inLen This is the number of samples in the input signal
     * to filter.
     *
     * @param inStep This is the step, or interleave factor, of the
     * input signal samples in the inSig array.
     *
     * @param lowSig This is the array where the low-pass output
     * signal is placed.
     *
     * @param lowOff This is the index in lowSig of the element where
     * to put the first low-pass output sample.
     *
     * @param lowStep This is the step, or interleave factor, of the
     * low-pass output samples in the lowSig array.
     *
     * @param highSig This is the array where the high-pass output
     * signal is placed.
     *
     * @param highOff This is the index in highSig of the element where
     * to put the first high-pass output sample.
     *
     * @param highStep This is the step, or interleave factor, of the
     * high-pass output samples in the highSig array.
     *
     * @see AnWTFilter#analyze_hpf
     * */
    public void analyze_hpf(float inSig[], int inOff, int inLen, int inStep,
                    float lowSig[], int lowOff, int lowStep,
                    float highSig[], int highOff, int highStep) {

        int i,maxi;
        int iStep = 2 * inStep; //Subsampling in inSig
        int ik;    //Indexing inSig
        int lk;    //Indexing lowSig
        int hk;    //Indexing highSig

        // Generate intermediate high frequency subband

        //Initialize counters
        ik = inOff;
        lk = lowOff;
        hk = highOff;

        if ( inLen>1 ) {
            // apply symmetric extension.
            highSig[hk] = inSig[ik] + 2*ALPHA*inSig[ik+inStep];
        }
        else {
            // Normalize for Nyquist gain
            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";
    }
}