jj2000.j2k.entropy.encoder.EntropyCoder Maven / Gradle / Ivy
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/*
* $RCSfile: EntropyCoder.java,v $
* $Revision: 1.1 $
* $Date: 2005/02/11 05:02:08 $
* $State: Exp $
*
* Class: EntropyCoder
*
* Description: The abstract class for entropy encoders
*
*
*
* 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.entropy.encoder;
import jj2000.j2k.StringSpec;
import jj2000.j2k.entropy.CBlkSizeSpec;
import jj2000.j2k.entropy.PrecinctSizeSpec;
import jj2000.j2k.entropy.StdEntropyCoderOptions;
import jj2000.j2k.image.ImgDataAdapter;
import jj2000.j2k.quantization.quantizer.CBlkQuantDataSrcEnc;
import jj2000.j2k.quantization.quantizer.Quantizer;
import jj2000.j2k.wavelet.Subband;
import jj2000.j2k.wavelet.analysis.SubbandAn;
import com.github.jaiimageio.jpeg2000.impl.J2KImageWriteParamJava;
/**
* This abstract class provides the general interface for block-based entropy
* encoders. The input to the entropy coder is the quantized wavelet
* coefficients, or codewords, represented in sign magnitude. The output is a
* compressed code-block with rate-distortion information.
*
* The source of data for objects of this class are 'CBlkQuantDataSrcEnc'
* objects.
*
*
For more details on the sign magnitude representation used see the
* Quantizer class.
*
*
This class provides default implemenations for most of the methods
* (wherever it makes sense), under the assumption that the image and
* component dimensions, and the tiles, are not modifed by the entropy
* coder. If that is not the case for a particular implementation then the
* methods should be overriden.
*
* @see Quantizer
* @see CBlkQuantDataSrcEnc
* */
public abstract class EntropyCoder extends ImgDataAdapter
implements CodedCBlkDataSrcEnc, StdEntropyCoderOptions {
/** The prefix for entropy coder options: 'C' */
public final static char OPT_PREFIX = 'C';
/** The list of parameters that is accepted for entropy coding. Options
* for entropy coding start with 'C'. */
private final static String [][] pinfo = {
{"Cblksiz", "[] "+
"[[] ]",
"Specifies the maximum code-block size to use for tile-component. "+
"The maximum width and height is 1024, however the surface area "+
"(i.e. width x height) must not exceed 4096. The minimum width and "+
"height is 4.","64 64"},
{"Cbypass", "[] true|false"+
"[ [] true|false ...]",
"Uses the lazy coding mode with the entropy coder. This will bypass "+
"the MQ coder for some of the coding passes, where the distribution "+
"is often close to uniform. Since the MQ codeword will be "+
"terminated "+
"at least once per lazy pass, it is important to use an efficient "+
"termination algorithm, see the 'Cterm' option."+
"'true' enables, 'false' disables it.","false"},
{"CresetMQ", "[] true|false"+
"[ [] true|false ...]",
"If this is enabled the probability estimates of the MQ coder are "+
"reset after each arithmetically coded (i.e. non-lazy) coding pass. "+
"'true' enables, 'false' disables it.","false"},
{"Creg_term", "[] true|false"+
"[ [] true|false ...]",
"If this is enabled the codeword (raw or MQ) is terminated on a "+
"byte boundary after each coding pass. In this case it is important "+
"to use an efficient termination algorithm, see the 'Cterm' option. "+
"'true' enables, 'false' disables it.","false"},
{"Ccausal","[] true|false"+
"[ [] true|false ...]",
"Uses vertically stripe causal context formation. If this is "+
"enabled "+
"the context formation process in one stripe is independant of the "+
"next stripe (i.e. the one below it). 'true' "+
"enables, 'false' disables it.","false"},
{"Cseg_symbol","[] true|false"+
"[ [] true|false ...]",
"Inserts an error resilience segmentation symbol in the MQ "+
"codeword at the end of "+
"each bit-plane (cleanup pass). Decoders can use this "+
"information to detect and "+
"conceal errors.'true' enables, 'false' disables "+
"it.","false"},
{"Cterm", "[] near_opt|easy|predict|full"+
"[ [] near_opt|easy|predict|full ...]",
"Specifies the algorithm used to terminate the MQ codeword. "+
"The most efficient one is 'near_opt', which delivers a codeword "+
"which in almost all cases is the shortest possible. The 'easy' is "+
"a simpler algorithm that delivers a codeword length that is close "+
"to the previous one (in average 1 bit longer). The 'predict' is"+
" almost "+
"the same as the 'easy' but it leaves error resilient information "+
"on "+
"the spare least significant bits (in average 3.5 bits), which can "+
"be used by a decoder to detect errors. The 'full' algorithm "+
"performs a full flush of the MQ coder and is highly inefficient.\n"+
"It is important to use a good termination policy since the MQ "+
"codeword can be terminated quite often, specially if the 'Cbypass'"+
" or "+
"'Creg_term' options are enabled (in the normal case it would be "+
"terminated once per code-block, while if 'Creg_term' is specified "+
"it will be done almost 3 times per bit-plane in each code-block).",
"near_opt"},
{"Clen_calc","[] near_opt|lazy_good|lazy"+
"[ [] ...]",
"Specifies the algorithm to use in calculating the necessary MQ "+
"length for each decoding pass. The best one is 'near_opt', which "+
"performs a rather sophisticated calculation and provides the best "+
"results. The 'lazy_good' and 'lazy' are very simple algorithms "+
"that "+
"provide rather conservative results, 'lazy_good' one being "+
"slightly "+
"better. Do not change this option unless you want to experiment "+
"the effect of different length calculation algorithms.","near_opt"},
{"Cpp","[] [ ] " +
"[ [] ...]",
"Specifies precinct partition dimensions for tile-component. The "+
"first "+
"two values apply to the highest resolution and the following ones "+
"(if "+
"any) apply to the remaining resolutions in decreasing order. If "+
"less "+
"values than the number of decomposition levels are specified, "+
"then the "+
"last two values are used for the remaining resolutions.", null},
};
/** The source of quantized wavelet coefficients */
protected CBlkQuantDataSrcEnc src;
/**
* Initializes the source of quantized wavelet coefficients.
*
* @param src The source of quantized wavelet coefficients.
* */
public EntropyCoder(CBlkQuantDataSrcEnc src) {
super(src);
this.src = src;
}
/**
* Returns the code-block width for the specified tile and component.
*
* @param t The tile index
*
* @param c the component index
*
* @return The code-block width for the specified tile and component
* */
public abstract int getCBlkWidth(int t, int c);
/**
* Returns the code-block height for the specified tile and component.
*
* @param t The tile index
*
* @param c the component index
*
* @return The code-block height for the specified tile and component
* */
public abstract int getCBlkHeight(int t, int c);
/**
* Returns the reversibility of the tile-component data that is provided
* by the object. Data is reversible when it is suitable for lossless and
* lossy-to-lossless compression.
*
* Since entropy coders themselves are always reversible, it returns
* the reversibility of the data that comes from the 'CBlkQuantDataSrcEnc'
* source object (i.e. ROIScaler).
*
* @param t Tile index
*
* @param c Component index
*
* @return true is the data is reversible, false if not.
*
* @see jj2000.j2k.roi.encoder.ROIScaler
* */
public boolean isReversible(int t,int c) {
return src.isReversible(t,c);
}
/**
* Returns a reference to the root of subband tree structure representing
* the subband decomposition for the specified tile-component.
*
* @param t The index of the tile.
*
* @param c The index of the component.
*
* @return The root of the subband tree structure, see Subband.
*
* @see SubbandAn
*
* @see Subband
* */
public SubbandAn getAnSubbandTree(int t,int c) {
return src.getAnSubbandTree(t,c);
}
/**
* 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 EntropyCoder object for the appropriate entropy coding
* parameters in the parameter list 'pl', and having 'src' as the source
* of quantized data.
*
* @param src The source of data to be entropy coded
*
* @param wp The parameter list (or options).
*
* @param cbks Code-block size specifications
*
* @param pss Precinct partition specifications
*
* @param bms By-pass mode specifications
*
* @param mqrs MQ-reset specifications
*
* @param rts Regular termination specifications
*
* @param css Causal stripes specifications
*
* @param sss Error resolution segment symbol use specifications
*
* @param lcs Length computation specifications
*
* @param tts Termination type specifications
*
* @exception IllegalArgumentException If an error occurs while parsing
* the options in 'pl'
* */
public static EntropyCoder createInstance(CBlkQuantDataSrcEnc src,
J2KImageWriteParamJava wp,
CBlkSizeSpec cblks,
PrecinctSizeSpec pss,
StringSpec bms,StringSpec mqrs,
StringSpec rts,StringSpec css,
StringSpec sss,StringSpec lcs,
StringSpec tts) {
// Check parameters
//pl.checkList(OPT_PREFIX,pl.toNameArray(pinfo));
return new StdEntropyCoder(src,cblks,pss,bms,mqrs,rts,css,sss,lcs,tts);
}
}