synwtfilterfloatlift9x7.java

jpeg2000编解码

/*
 * CVS identifier:
 *
 * $Id: SynWTFilterFloatLift9x7.java,v 1.1.1.1 2002/07/22 09:26:55 grosbois Exp $
 *
 * Class:                   SynWTFilterFloatLift9x7
 *
 * Description:             A synthetizing wavelet filter implementing the
 *                          lifting 9x7 transform.
 *
 *
 *
 * COPYRIGHT:
 * 
 * This software module was originally developed by Rapha雔 Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askel鰂 (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, F閘ix 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.synthesis;

import jj2000.j2k.wavelet.*;
import jj2000.j2k.image.*;
import jj2000.j2k.*;

/**
 * This class inherits from the synthesis wavelet filter definition for int
 * data. It implements the inverse wavelet transform specifically for the 9x7
 * filter. The implementation is based on the lifting scheme.
 *
 * <P>See the SynWTFilter 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 SynWTFilter
 * @see SynWTFilterFloat
 * */
public class SynWTFilterFloatLift9x7 extends SynWTFilterFloat {
    
    /** 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 = 0.4435068522f;

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

    /** The value of the high-pass subband normalization factor */
    public final static float KH = 1.230174106f;
    
    /**
     * An implementation of the synthetize_lpf() method that works on int
     * data, for the inverse 9x7 wavelet transform using the lifting
     * scheme. See the general description of the synthetize_lpf() method in
     * the SynWTFilter class for more details.
     *
     * <P>The low-pass and high-pass subbands are normalized by respectively a
     * factor of 1/KL and a factor of 1/KH
     *
     * <P>The coefficients of the first lifting step are [-DELTA 1 -DELTA]. 
     *
     * <P>The coefficients of the second lifting step are [-GAMMA 1 -GAMMA].
     * 
     * <P>The coefficients of the third lifting step are [-BETA 1 -BETA]. 
     *
     * <P>The coefficients of the fourth lifting step are [-ALPHA 1 -ALPHA].
     *
     * @param lowSig This is the array that contains the low-pass input
     * signal.
     *
     * @param lowOff This is the index in lowSig of the first sample to
     * filter.
     *
     * @param lowLen This is the number of samples in the low-pass input
     * signal to filter.
     *
     * @param lowStep This is the step, or interleave factor, of the low-pass
     * input signal samples in the lowSig array.
     *
     * @param highSig This is the array that contains the high-pass input
     * signal.
     *
     * @param highOff This is the index in highSig of the first sample to
     * filter.
     *
     * @param highLen This is the number of samples in the high-pass input
     * signal to filter.
     *
     * @param highStep This is the step, or interleave factor, of the
     * high-pass input signal samples in the highSig array.
     *
     * @param outSig This is the array where the output signal is placed. It
     * should be long enough to contain the output signal.
     *
     * @param outOff This is the index in outSig of the element where to put
     * the first output sample.
     *
     * @param outStep This is the step, or interleave factor, of the output
     * samples in the outSig array.
     *
     * @see SynWTFilter#synthetize_lpf
     * */
    public
        void synthetize_lpf(float[] lowSig,int lowOff,int lowLen,int lowStep,
                            float[] highSig,int highOff,int highLen,
                            int highStep,
                            float[] outSig, int outOff, int outStep) {
                        
        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
        
        // Generate intermediate low frequency subband
	float sample = 0;

        //Initialize counters
        lk = lowOff;
        hk = highOff;
        ik = outOff;
        
        //Handle tail boundary effect. Use symmetric extension
        if(outLen>1) {
            outSig[ik] = lowSig[lk]/KL - 2*DELTA*highSig[hk]/KH;
        }
	else {
	    outSig[ik] = lowSig[lk];
	}
        
        lk += lowStep;
        hk += highStep;
    	ik += iStep;
    	
        //Apply lifting step to each "inner" sample
        for(i=2; i<outLen-1; i+=2, ik+=iStep, lk+=lowStep, hk+=highStep) {
            outSig[ik] = lowSig[lk]/KL - 
            	DELTA*(highSig[hk-highStep] + highSig[hk])/KH;
        }
        
        //Handle head boundary effect if input signal has odd length
        if(outLen%2 == 1) {
            if(outLen>2){
                outSig[ik] = lowSig[lk]/KL - 
                2*DELTA*highSig[hk-highStep]/KH;
            }
        }
        
        // Generate intermediate high 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, ik+=iStep, hk+=highStep, lk+=lowStep) {
            outSig[ik] = highSig[hk]/KH - 
                GAMMA*(outSig[ik-outStep] + outSig[ik+outStep]);
    	}

        //Handle head boundary effect if output signal has even length
        if(outLen % 2 == 0) {
            outSig[ik] = highSig[hk]/KH - 2*GAMMA*outSig[ik-outStep];
        }       

        // Generate even samples (inverse low-pass filter)
        
        //Initialize counters
        ik = outOff;
 
        //Handle tail boundary effect
        //If access the overlap then perform the lifting step.
    	if(outLen>1) {
            outSig[ik] -= 2*BETA*outSig[ik+outStep];
        }
        ik += iStep;
 
        //Apply lifting step to each "inner" sample
        for(i=2; i<outLen-1; i+=2, ik+=iStep) {
            outSig[ik] -= BETA*(outSig[ik-outStep] + outSig[ik+outStep]);
        }
        
        //Handle head boundary effect if input signal has odd length
        if(outLen%2 == 1 && outLen>2) {
            outSig[ik] -= 2*BETA*outSig[ik-outStep];
        }

        // Generate odd samples (inverse high pass-filter)
         
        //Initialize counters
        ik = outOff + outStep;

        //Apply first lifting step to each "inner" sample
        for(i=1; i<outLen-1; i+=2, ik+=iStep) {           
            outSig[ik] -= ALPHA*(outSig[ik-outStep] + outSig[ik+outStep]);
        }

        //Handle head boundary effect if input signal has even length
        if(outLen%2 == 0) {
            outSig[ik] -= 2*ALPHA*outSig[ik-outStep];
        }
    }
    
    /**
     * An implementation of the synthetize_hpf() method that works on int
     * data, for the inverse 9x7 wavelet transform using the lifting
     * scheme. See the general description of the synthetize_hpf() method in
     * the SynWTFilter class for more details.
     *
     * <P>The low-pass and high-pass subbands are normalized by respectively
     * a factor of 1/KL and a factor of 1/KH   
     *
     * <P>The coefficients of the first lifting step are [-DELTA 1 -DELTA]. 
     *
     * <P>The coefficients of the second lifting step are [-GAMMA 1 -GAMMA].
     * 
     * <P>The coefficients of the third lifting step are [-BETA 1 -BETA]. 
     *
     * <P>The coefficients of the fourth lifting step are [-ALPHA 1 -ALPHA].
     *
     * @param lowSig This is the array that contains the low-pass
     * input signal.
     *
     * @param lowOff This is the index in lowSig of the first sample to
     * filter.
     *
     * @param lowLen This is the number of samples in the low-pass input
     * signal to filter.
     *
     * @param lowStep This is the step, or interleave factor, of the low-pass
     * input signal samples in the lowSig array.
     *
     * @param highSig This is the array that contains the high-pass input
     * signal.
     *
     * @param highOff This is the index in highSig of the first sample to
     * filter.
     *
     * @param highLen This is the number of samples in the high-pass input
     * signal to filter.
     *
     * @param highStep This is the step, or interleave factor, of the
     * high-pass input signal samples in the highSig array.
     *
     * @param outSig This is the array where the output signal is placed. It
     * should be long enough to contain the output signal.
     *
     * @param outOff This is the index in outSig of the element where to put
     * the first output sample.
     *
     * @param outStep This is the step, or interleave factor, of the output
     * samples in the outSig array.
     *
     * @see SynWTFilter#synthetize_hpf
     * */
    public
        void synthetize_hpf(float[] lowSig,int lowOff,int lowLen,int lowStep,
			    float[] highSig,int highOff,int highLen,
			    int highStep,float[] outSig,int outOff,
			    int outStep) {