stddequantizer.java

jpeg2000算法实现

/*
 * CVS identifier:
 *
 * $Id: StdDequantizer.java,v 1.10 2001/02/14 10:45:02 grosbois Exp $
 *
 * Class:                   StdDequantizer
 *
 * Description:             Scalar deadzone dequantizer that returns integers
 *                          or floats.
 *                          This is a merger of the ScalarDZDeqInt and
 *                          ScalarDZDeqFloat classes by Joel Askelof and Diego
 *                          Santa Cruz.
 *
 *
 *
 * 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.quantization.dequantizer;

import jj2000.j2k.wavelet.synthesis.*;
import jj2000.j2k.entropy.decoder.*;
import jj2000.j2k.quantization.*;
import jj2000.j2k.codestream.*;
import jj2000.j2k.entropy.*;
import jj2000.j2k.decoder.*;
import jj2000.j2k.image.*;
import jj2000.j2k.io.*;

import java.io.*;

/**
 * This class implements a scalar dequantizer with deadzone. The output can be
 * either integer ('int') or floating-point ('float') data. The dequantization
 * step sizes and other parameters are taken from a StdDequantizerParams
 * class, which inherits from DequantizerParams.
 *
 * <P>Sign magnitude representation is used (instead of two's complement) for
 * the input data. The most significant bit is used for the sign (0 if
 * positive, 1 if negative). Then the magnitude of the quantized coefficient
 * is stored in the next most significat bits. The most significant magnitude
 * bit corresponds to the most significant bit-plane and so on.
 *
 * <P>When reversible quantization is used, this class only converts between
 * the sign-magnitude representation and the integer (or eventually
 * fixed-point) output, since there is no true quantization.
 *
 * <P>The output data is fixed-point two's complement for 'int' output and
 * floating-point for 'float' output. The type of output and the number number
 * of fractional bits for 'int' output are defined at the constructor. Each
 * component may have a different number of fractional bits.
 *
 * <P>The reconstruction levels used by the dequantizer are exactly what is
 * received from the entropy decoder. It is assumed that the entropy decoder
 * always returns codewords that are midways in the decoded intervals. In this
 * way the dequantized values will always lie midways in the quantization
 * intervals.
 * */
public class StdDequantizer extends Dequantizer {

    /** The quantizer type spec */
    private QuantTypeSpec qts;

    /** The quantizer step sizes  spec */
    private QuantStepSizeSpec qsss;

    /** The number of guard bits spec */
    private GuardBitsSpec gbs;
    
    /** The decoding parameters of the dequantizer */
    private StdDequantizerParams params;

    /** The 'DataBlkInt' object used to request data, used when output data is
     * not int */
    private DataBlkInt inblk;

    /** Type of the current output data */
    private int outdtype;

    /**
     * Initializes the source of compressed data. And sets the number of range
     * bits and fraction bits and receives the parameters for the dequantizer.
     *
     * @param src From where to obtain the quantized data.
     *
     * @param rb The number of "range bits" (bitdepth) for each component
     * (must be the "range bits" of the un-transformed components). For a
     * definition of "range bits" see the getNomRangeBits() method.
     *
     * @param qts The quantizer type spec
     *
     * @param qsss The dequantizer step sizes spec
     *
     * @see Dequantizer#getNomRangeBits
     *
     * @exception IllegalArgumentException Thrown if 'outdt' is neither
     * TYPE_FLOAT nor TYPE_INT, or if 'param' specify reversible quantization
     * and 'outdt' is not TYPE_INT or 'fp' has non-zero values, or if 'outdt'
     * is TYPE_FLOAT and 'fp' has non-zero values.
     * */
    public StdDequantizer(CBlkQuantDataSrcDec src,int[] utrb,
                               DecoderSpecs decSpec){
        super(src,utrb,decSpec);

        if(utrb.length != src.getNumComps()){
            throw new IllegalArgumentException("Invalid rb argument");
        }
        this.qsss = decSpec.qsss;
	this.qts = decSpec.qts;
        this.gbs = decSpec.gbs;
    }

    /**
     * Returns the position of the fixed point in the output data for the
     * specified component. This is the position of the least significant
     * integral (i.e. non-fractional) bit, which is equivalent to the number
     * of fractional bits. For instance, for fixed-point values with 2
     * fractional bits, 2 is returned. For floating-point data this value does
     * not apply and 0 should be returned. Position 0 is the position of the
     * least significant bit in the data. If the output data is 'float' then 0
     * is always returned.
     *
     * <P><u>Note:</u> Fractional bits are no more supported by JJ2000. 
     *
     * @param c The index of the component.
     *
     * @return The position of the fixed-point, which is the same as
     * the number of fractional bits. For floating-point data 0 is
     * returned.
     * */
    public int getFixedPoint(int c){
        return 0;
    }

    /**
     * Returns the specified code-block in the current tile for the specified
     * component, as a copy (see below).
     *
     * <P>The returned code-block may be progressive, which is indicated by
     * the 'progressive' variable of the returned 'DataBlk' object. If a
     * code-block is progressive it means that in a later request to this
     * method for the same code-block it is possible to retrieve data which is
     * a better approximation, since meanwhile more data to decode for the
     * code-block could have been received. If the code-block is not
     * progressive then later calls to this method for the same code-block
     * will return the exact same data values.
     *
     * <P>The data returned by this method is always a copy of the internal
     * data of this object, if any, and it can be modified "in place" without
     * any problems after being returned. The 'offset' of the returned data is 
     * 0, and the 'scanw' is the same as the code-block width. See the
     * 'DataBlk' class.
     *
     * @param c The component for which to return the next code-block.
     *
     * @param m The vertical index of the code-block to return, in the
     * specified subband.
     *
     * @param n The horizontal index of the code-block to return, in the
     * specified subband.