Class Quantizer
- All Implemented Interfaces:
ImgData,CBlkQuantDataSrcEnc,ForwWTDataProps
- Direct Known Subclasses:
StdQuantizer
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.
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final charThe prefix for quantizer options: 'Q'protected CBlkWTDataSrcThe source of wavelet transform coefficientsFields inherited from class jj2000.j2k.image.ImgDataAdapter
imgdatasrc, tIdx -
Constructor Summary
ConstructorsConstructorDescriptionQuantizer(CBlkWTDataSrc src) Initializes the source of wavelet transform coefficients. -
Method Summary
Modifier and TypeMethodDescriptionprotected abstract voidcalcSbParams(SubbandAn sb, int n) Calculates the parameters of the SubbandAn objects that depend on the Quantizer.static QuantizerCreates 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.getAnSubbandTree(int t, int c) Returns a reference to the subband tree structure representing the subband decomposition for the specified tile-component.intgetCbULX()Returns the horizontal offset of the code-block partition.intgetCbULY()Returns the vertical offset of the code-block partition.abstract intgetMaxMagBits(int c) Returns the maximum number of magnitude bits in any subband in the current tile.abstract intgetNumGuardBits(int t, int c) Returns the number of guard bits used by this quantizer in the given tile-component.static String[][]Returns the parameters that are used in this class and implementing classes.abstract booleanisDerived(int t, int c) Returns true if the quantizer of given tile-component uses derived quantization step sizes.Methods inherited from class jj2000.j2k.image.ImgDataAdapter
getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getCompULX, getCompULY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomRangeBits, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth, nextTile, setTileMethods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods inherited from interface jj2000.j2k.quantization.quantizer.CBlkQuantDataSrcEnc
getNextCodeBlock, getNextInternCodeBlockMethods inherited from interface jj2000.j2k.wavelet.analysis.ForwWTDataProps
isReversibleMethods inherited from interface jj2000.j2k.image.ImgData
getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getCompULX, getCompULY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomRangeBits, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth, nextTile, setTile
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Field Details
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OPT_PREFIX
public static final char OPT_PREFIXThe prefix for quantizer options: 'Q'- See Also:
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src
The source of wavelet transform coefficients
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Constructor Details
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Quantizer
Initializes the source of wavelet transform coefficients.- Parameters:
src- The source of wavelet transform coefficients.
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Method Details
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getNumGuardBits
public abstract int getNumGuardBits(int t, int c) Returns the number of guard bits used by this quantizer in the given tile-component.- Parameters:
t- Tile indexc- Component index- Returns:
- The number of guard bits
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isDerived
public abstract boolean isDerived(int t, int c) Returns true if the quantizer of given tile-component uses derived quantization step sizes.- Parameters:
t- Tile indexc- Component index- Returns:
- True if derived quantization is used.
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calcSbParams
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'.- Parameters:
sb- The root of the subband tree.n- The component index.- See Also:
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getAnSubbandTree
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().
- Specified by:
getAnSubbandTreein interfaceForwWTDataProps- Parameters:
t- The index of the tile.c- The index of the component.- Returns:
- The subband tree structure, see SubbandAn.
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getCbULX
public int getCbULX()Returns the horizontal offset of the code-block partition. Allowable values are 0 and 1, nothing else.- Specified by:
getCbULXin interfaceForwWTDataProps
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getCbULY
public int getCbULY()Returns the vertical offset of the code-block partition. Allowable values are 0 and 1, nothing else.- Specified by:
getCbULYin interfaceForwWTDataProps
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getParameterInfo
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.- Returns:
- the options name, their synopsis and their explanation, or null if no options are supported.
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createInstance
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.- Parameters:
src- The source of data to be quantizedwp- The encoder parameters- Throws:
IllegalArgumentException- If an error occurs while parsing the options in 'pl'
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getMaxMagBits
public abstract int getMaxMagBits(int c) Returns the maximum number of magnitude bits in any subband in the current tile.- Parameters:
c- the component number- Returns:
- The maximum number of magnitude bits in all subbands of the current tile.
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