stddequantizerparams.java

jpeg2000编解码

/*
 * CVS identifier:
 *
 * $Id: StdDequantizerParams.java,v 1.1.1.1 2002/07/22 09:26:52 grosbois Exp $
 *
 * Class:                   StdDequantizerParams
 *
 * Description:             Parameters for the scalar deadzone dequantizers
 *
 *
 *
 * 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.io.*;
import jj2000.j2k.wavelet.*;
import jj2000.j2k.quantization.*;
import jj2000.j2k.entropy.decoder.*;
import jj2000.j2k.image.*;
import jj2000.j2k.util.*;
import jj2000.j2k.codestream.*;
import jj2000.j2k.codestream.reader.*;

import java.io.*;

/**
 * This class holds the parameters for the scalar deadzone dequantizer
 * (StdDequantizer class) for the current tile. Its constructor decodes the
 * parameters from the main header and tile headers.
 *
 * @see StdDequantizer
 * */
public class StdDequantizerParams extends DequantizerParams {

    /**
     * The quantization step "exponent" value, for each resolution level and
     * subband, as it appears in the codestream. The first index is the
     * resolution level, and the second the subband index (within the
     * resolution level), as specified in the Subband class. When in derived
     * quantization mode only the first resolution level (level 0) appears.
     *
     * <P>For non-reversible systems this value corresponds to ceil(log2(D')),
     * where D' is the quantization step size normalized to data of a dynamic
     * range of 1. The true quantization step size is (2^R)*D', where R is
     * ceil(log2(dr)), where 'dr' is the dynamic range of the subband samples,
     * in the corresponding subband.
     *
     * <P>For reversible systems the exponent value in 'exp' is used to
     * determine the number of magnitude bits in the quantized
     * coefficients. It is, in fact, the dynamic range of the subband data.
     *
     * <P>In general the index of the first subband in a resolution level is
     * not 0. The exponents appear, within each resolution level, at their
     * subband index, and not in the subband order starting from 0. For
     * instance, resolution level 3, the first subband has the index 16, then
     * the exponent of the subband is exp[3][16], not exp[3][0].
     *
     * @see Subband
     * */
    public int exp[][];

    /**
     * The quantization step for non-reversible systems, normalized to a
     * dynamic range of 1, for each resolution level and subband, as derived
     * from the exponent-mantissa representation in the codestream. The first
     * index is the resolution level, and the second the subband index (within
     * the resolution level), as specified in the Subband class. When in
     * derived quantization mode only the first resolution level (level 0)
     * appears.
     *
     * <P>The true step size D is obtained as follows: D=(2^R)*D', where
     * 'R=ceil(log2(dr))' and 'dr' is the dynamic range of the subband
     * samples, in the corresponding subband.
     *
     * <P>This value is 'null' for reversible systems (i.e. there is no true
     * quantization, 'D' is always 1).
     *
     * <P>In general the index of the first subband in a resolution level is
     * not 0. The steps appear, within each resolution level, at their subband
     * index, and not in the subband order starting from 0. For instance, if
     * resolution level 3, the first subband has the index 16, then the step
     * of the subband is nStep[3][16], not nStep[3][0].
     *
     * @see Subband
     * */
    public float nStep[][];

    /**
     * Returns the type of the dequantizer for which the parameters are. The
     * types are defined in the Dequantizer class.
     *
     * @return The type of the dequantizer for which the parameters
     * are. Always Q_TYPE_SCALAR_DZ.
     *
     * @see Dequantizer
     * */
    public int getDequantizerType() {
        return QuantizationType.Q_TYPE_SCALAR_DZ;
    }

}