jj2000.j2k.quantization.dequantizer

Class StdDequantizer

java.lang.Object

jj2000.j2k.wavelet.synthesis.MultiResImgDataAdapter

jj2000.j2k.quantization.dequantizer.Dequantizer

jj2000.j2k.quantization.dequantizer.StdDequantizer

All Implemented Interfaces:

CBlkWTDataSrcDec, InvWTData, MultiResImgData

public class StdDequantizer
extends Dequantizer

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.

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.

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.

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.

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.

Field Summary

Fields

Modifier and Type	Field and Description
private GuardBitsSpec	gbs The number of guard bits spec
private DataBlkInt	inblk The 'DataBlkInt' object used to request data, used when output data is not int
private int	outdtype Type of the current output data
private StdDequantizerParams	params The decoding parameters of the dequantizer
private QuantStepSizeSpec	qsss The quantizer step sizes spec
private QuantTypeSpec	qts The quantizer type spec

Fields inherited from class jj2000.j2k.quantization.dequantizer.Dequantizer

OPT_PREFIX, rb, src, utrb

Fields inherited from class jj2000.j2k.wavelet.synthesis.MultiResImgDataAdapter

mressrc, tIdx

Constructor Summary

Constructors

Constructor and Description
StdDequantizer(CBlkQuantDataSrcDec src, int[] utrb, DecoderSpecs decSpec) Initializes the source of compressed data.

Method Summary

Methods

Modifier and Type	Method and Description
DataBlk	getCodeBlock(int c, int m, int n, SubbandSyn sb, DataBlk cblk) Returns the specified code-block in the current tile for the specified component, as a copy (see below).
int	getFixedPoint(int c) Returns the position of the fixed point in the output data for the specified component.
DataBlk	getInternCodeBlock(int c, int m, int n, SubbandSyn sb, DataBlk cblk) Returns the specified code-block in the current tile for the specified component (as a reference or copy).

Methods inherited from class jj2000.j2k.quantization.dequantizer.Dequantizer

getCbULX, getCbULY, getNomRangeBits, getParameterInfo, getSynSubbandTree, nextTile, setTile

Methods inherited from class jj2000.j2k.wavelet.synthesis.MultiResImgDataAdapter

getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getResULX, getResULY, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface jj2000.j2k.wavelet.synthesis.MultiResImgData

getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getResULX, getResULY, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth

Field Detail

qts

private QuantTypeSpec qts

The quantizer type spec

qsss

private QuantStepSizeSpec qsss

The quantizer step sizes spec

gbs

private GuardBitsSpec gbs

The number of guard bits spec

params

private StdDequantizerParams params

The decoding parameters of the dequantizer

inblk

private DataBlkInt inblk

The 'DataBlkInt' object used to request data, used when output data is not int

outdtype

private int outdtype

Type of the current output data

Constructor Detail

StdDequantizer

public StdDequantizer(CBlkQuantDataSrcDec src,
              int[] utrb,
              DecoderSpecs decSpec)

Initializes the source of compressed data. And sets the number of range bits and fraction bits and receives the parameters for the dequantizer.

Parameters:

src - From where to obtain the quantized data.

utrb - 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.

decSpec - The decoder specifications

Throws:

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.

See Also:

Dequantizer.getNomRangeBits(int)

Method Detail

getFixedPoint

public int getFixedPoint(int c)

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.

Note: Fractional bits are no more supported by JJ2000.

Parameters:

c - The index of the component.

Returns:

The position of the fixed-point, which is the same as the number of fractional bits. For floating-point data 0 is returned.

getCodeBlock

public final DataBlk getCodeBlock(int c,
                   int m,
                   int n,
                   SubbandSyn sb,
                   DataBlk cblk)

Returns the specified code-block in the current tile for the specified component, as a copy (see below).

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.

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.

Parameters:

c - The component for which to return the next code-block.

m - The vertical index of the code-block to return, in the specified subband.

n - The horizontal index of the code-block to return, in the specified subband.

sb - The subband in which the code-block to return is.

cblk - If non-null this object will be used to return the new code-block. If null a new one will be allocated and returned. If the "data" array of the object is non-null it will be reused, if possible, to return the data.

Returns:

The next code-block in the current tile for component 'n', or null if all code-blocks for the current tile have been returned.

See Also:

DataBlk

getInternCodeBlock

public final DataBlk getInternCodeBlock(int c,
                         int m,
                         int n,
                         SubbandSyn sb,
                         DataBlk cblk)

Returns the specified code-block in the current tile for the specified component (as a reference or copy).

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.

The data returned by this method can be the data in the internal buffer of this object, if any, and thus can not be modified by the caller. The 'offset' and 'scanw' of the returned data can be arbitrary. See the 'DataBlk' class.

Parameters:

c - The component for which to return the next code-block.

m - The vertical index of the code-block to return, in the specified subband.

n - The horizontal index of the code-block to return, in the specified subband.

sb - The subband in which the code-block to return is.

cblk - If non-null this object will be used to return the new code-block. If null a new one will be allocated and returned. If the "data" array of the object is non-null it will be reused, if possible, to return the data.

Returns:

The next code-block in the current tile for component 'n', or null if all code-blocks for the current tile have been returned.

See Also:

DataBlk