jj2000.j2k.quantization.quantizer.Quantizer Maven / Gradle / Ivy
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/*
* $RCSfile: Quantizer.java,v $
* $Revision: 1.1 $
* $Date: 2005/02/11 05:02:20 $
* $State: Exp $
*
* Class: Quantizer
*
* Description: An abstract class for quantizers
*
*
*
* 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.quantization.quantizer;
//import jj2000.j2k.encoder.*;
import jj2000.j2k.image.ImgDataAdapter;
import jj2000.j2k.wavelet.Subband;
import jj2000.j2k.wavelet.analysis.CBlkWTDataSrc;
import jj2000.j2k.wavelet.analysis.SubbandAn;
import com.github.jaiimageio.jpeg2000.impl.J2KImageWriteParamJava;
/**
* This abstract class provides the general interface for quantizers. The
* input of a quantizer is the output of a wavelet transform. The output of
* the quantizer is the set of quantized wavelet coefficients represented in
* sign-magnitude notation (see below).
*
* This class provides default implementation for most of the methods
* (wherever it makes sense), under the assumption that the image, component
* dimensions, and the tiles, are not modifed by the quantizer. If it is not
* the case for a particular implementation, then the methods should be
* overriden.
*
* Sign magnitude representation is used (instead of two's complement) for
* the output 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 M most significat bits. The rest of the bits (least
* significant bits) can contain a fractional value of the quantized
* coefficient. This fractional value is not to be coded by the entropy
* coder. However, it can be used to compute rate-distortion measures with
* greater precision.
*
* The value of M is determined for each subband as the sum of the number
* of guard bits G and the nominal range of quantized wavelet coefficients in
* the corresponding subband (Rq), minus 1:
*
* M = G + Rq -1
*
* The value of G should be the same for all subbands. The value of Rq
* depends on the quantization step size, the nominal range of the component
* before the wavelet transform and the analysis gain of the subband (see
* Subband).
*
* The blocks of data that are requested should not cross subband
* boundaries.
*
* NOTE: At the moment only quantizers that implement the
* 'CBlkQuantDataSrcEnc' interface are supported.
*
* @see Subband
* */
public abstract class Quantizer extends ImgDataAdapter
implements CBlkQuantDataSrcEnc {
/** The prefix for quantizer options: 'Q' */
public final static char OPT_PREFIX = 'Q';
/** The list of parameters that is accepted for quantization. Options
* for quantization start with 'Q'. */
private final static String [][] pinfo = {
{ "Qtype", "[] "+
"[ [] ...]",
"Specifies which quantization type to use for specified "+
"tile-component. The default type is either 'reversible' or "+
"'expounded' depending on whether or not the '-lossless' option "+
" is specified.\n"+
" : see general note.\n"+
": Supported quantization types specification are : "+
"'reversible' "+
"(no quantization), 'derived' (derived quantization step size) and "+
"'expounded'.\n"+
"Example: -Qtype reversible or -Qtype t2,4-8 c2 reversible t9 "+
"derived.",null},
{ "Qstep", "[] "+
"[ [] ...]",
"This option specifies the base normalized quantization step "+
"size (bnss) for tile-components. It is normalized to a "+
"dynamic range of 1 in the image domain. This parameter is "+
"ignored in reversible coding. The default value is '1/128'"+
" (i.e. 0.0078125).",
"0.0078125"},
{ "Qguard_bits", "[] "+
"[ [] ...]",
"The number of bits used for each tile-component in the quantizer"+
" to avoid overflow (gb).","2"},
};
/** The source of wavelet transform coefficients */
protected CBlkWTDataSrc src;
/**
* Initializes the source of wavelet transform coefficients.
*
* @param src The source of wavelet transform coefficients.
* */
public Quantizer(CBlkWTDataSrc src) {
super(src);
this.src = src;
}
/**
* Returns the number of guard bits used by this quantizer in the
* given tile-component.
*
* @param t Tile index
*
* @param c Component index
*
* @return The number of guard bits
* */
public abstract int getNumGuardBits(int t,int c);
/**
* Returns true if the quantizer of given tile-component uses derived
* quantization step sizes.
*
* @param t Tile index
*
* @param c Component index
*
* @return True if derived quantization is used.
* */
public abstract boolean isDerived(int t,int c);
/**
* Calculates the parameters of the SubbandAn objects that depend on the
* Quantizer. The 'stepWMSE' field is calculated for each subband which is
* a leaf in the tree rooted at 'sb', for the specified component. The
* subband tree 'sb' must be the one for the component 'n'.
*
* @param sb The root of the subband tree.
*
* @param n The component index.
*
* @see SubbandAn#stepWMSE
* */
protected abstract void calcSbParams(SubbandAn sb, int n);
/**
* Returns a reference to the subband tree structure representing the
* subband decomposition for the specified tile-component.
*
* This method gets the subband tree from the source and then
* calculates the magnitude bits for each leaf using the method
* calcSbParams().
*
* @param t The index of the tile.
*
* @param c The index of the component.
*
* @return The subband tree structure, see SubbandAn.
*
* @see SubbandAn
*
* @see Subband
*
* @see #calcSbParams
* */
public SubbandAn getAnSubbandTree(int t,int c) {
SubbandAn sbba;
// Ask for the wavelet tree of the source
sbba = src.getAnSubbandTree(t,c);
// Calculate the stepWMSE
calcSbParams(sbba,c);
return sbba;
}
/**
* Returns the horizontal offset of the code-block partition. Allowable
* values are 0 and 1, nothing else.
* */
public int getCbULX() {
return src.getCbULX();
}
/**
* Returns the vertical offset of the code-block partition. Allowable
* values are 0 and 1, nothing else.
* */
public int getCbULY() {
return src.getCbULY();
}
/**
* Returns the parameters that are used in this class and implementing
* classes. It returns a 2D String array. Each of the 1D arrays is for a
* different option, and they have 3 elements. The first element is the
* option name, the second one is the synopsis, the third one is a long
* description of what the parameter is and the fourth is its default
* value. The synopsis or description may be 'null', in which case it is
* assumed that there is no synopsis or description of the option,
* respectively. Null may be returned if no options are supported.
*
* @return the options name, their synopsis and their explanation,
* or null if no options are supported.
* */
public static String[][] getParameterInfo() {
return pinfo;
}
/**
* Creates a Quantizer object for the appropriate type of quantization
* specified in the options in the parameter list 'pl', and having 'src'
* as the source of data to be quantized. The 'rev' flag indicates if the
* quantization should be reversible.
*
* NOTE: At the moment only sources of wavelet data that implement the
* 'CBlkWTDataSrc' interface are supported.
*
* @param src The source of data to be quantized
*
* @param encSpec Encoder specifications
*
* @exception IllegalArgumentException If an error occurs while parsing
* the options in 'pl'
* */
public static Quantizer createInstance(CBlkWTDataSrc src,
J2KImageWriteParamJava wp) {
// Instantiate quantizer
return new StdQuantizer(src,wp);
}
/**
* Returns the maximum number of magnitude bits in any subband in the
* current tile.
*
* @param c the component number
*
* @return The maximum number of magnitude bits in all subbands of the
* current tile.
* */
public abstract int getMaxMagBits(int c);
}