Class StdQuantizer
- java.lang.Object
-
- jj2000.j2k.image.ImgDataAdapter
-
- jj2000.j2k.quantization.quantizer.Quantizer
-
- jj2000.j2k.quantization.quantizer.StdQuantizer
-
- All Implemented Interfaces:
ImgData
,CBlkQuantDataSrcEnc
,ForwWTDataProps
public class StdQuantizer extends Quantizer
This class implements scalar quantization of integer or floating-point valued source data. The source data is the wavelet transformed image data and the output is the quantized wavelet coefficients represented in sign-magnitude (see below).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.
-
-
Field Summary
Fields Modifier and Type Field Description static int
QSTEP_EXPONENT_BITS
The number of exponent bits for the quantization stepsstatic int
QSTEP_MANTISSA_BITS
The number of mantissa bits for the quantization stepsstatic int
QSTEP_MAX_EXPONENT
The maximum value of the exponent for the quantization stepsstatic int
QSTEP_MAX_MANTISSA
The maximum value of the mantissa for the quantization steps-
Fields inherited from class jj2000.j2k.quantization.quantizer.Quantizer
OPT_PREFIX, src
-
Fields inherited from class jj2000.j2k.image.ImgDataAdapter
imgdatasrc, tIdx
-
-
Constructor Summary
Constructors Constructor Description StdQuantizer(CBlkWTDataSrc src, J2KImageWriteParamJava wp)
Initializes the source of wavelet transform coefficients.
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
calcSbParams(SubbandAn sb, int c)
Calculates the parameters of the SubbandAn objects that depend on the Quantizer.static int
convertToExpMantissa(float step)
Converts the floating point value to its exponent-mantissa representation.int
getMaxMagBits(int c)
Returns the maximum number of magnitude bits in any subband of the current tile.CBlkWTData
getNextCodeBlock(int c, CBlkWTData cblk)
Returns the next code-block in the current tile for the specified component, as a copy (see below).CBlkWTData
getNextInternCodeBlock(int c, CBlkWTData cblk)
Returns the next code-block in the current tile for the specified component.int
getNumGuardBits(int t, int c)
Returns the number of guard bits used by this quantizer in the given tile-component.QuantTypeSpec
getQuantTypeSpec()
Returns the quantization type spec object associated to the quantizer.boolean
isDerived(int t, int c)
Returns true if given tile-component uses derived quantization step sizes.boolean
isReversible(int t, int c)
Returns true if the quantized data is reversible, for the specified tile-component.-
Methods inherited from class jj2000.j2k.quantization.quantizer.Quantizer
createInstance, getAnSubbandTree, getCbULX, getCbULY, getParameterInfo
-
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, setTile
-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
-
Methods 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
-
-
-
-
Field Detail
-
QSTEP_MANTISSA_BITS
public static final int QSTEP_MANTISSA_BITS
The number of mantissa bits for the quantization steps- See Also:
- Constant Field Values
-
QSTEP_EXPONENT_BITS
public static final int QSTEP_EXPONENT_BITS
The number of exponent bits for the quantization steps- See Also:
- Constant Field Values
-
QSTEP_MAX_MANTISSA
public static final int QSTEP_MAX_MANTISSA
The maximum value of the mantissa for the quantization steps- See Also:
- Constant Field Values
-
QSTEP_MAX_EXPONENT
public static final int QSTEP_MAX_EXPONENT
The maximum value of the exponent for the quantization steps- See Also:
- Constant Field Values
-
-
Constructor Detail
-
StdQuantizer
public StdQuantizer(CBlkWTDataSrc src, J2KImageWriteParamJava wp)
Initializes the source of wavelet transform coefficients. The constructor takes information on whether the quantizer is in reversible, derived or expounded mode. If the quantizer is reversible the value of 'derived' is ignored. If the source data is not integer (int) then the quantizer can not be reversible.After initializing member attributes, getAnSubbandTree is called for all components setting the 'stepWMSE' for all subbands in the current tile.
- Parameters:
src
- The source of wavelet transform coefficients.wp
- The encoder parameters
-
-
Method Detail
-
getQuantTypeSpec
public QuantTypeSpec getQuantTypeSpec()
Returns the quantization type spec object associated to the quantizer.- Returns:
- The quantization type spec
-
getNumGuardBits
public int getNumGuardBits(int t, int c)
Returns the number of guard bits used by this quantizer in the given tile-component.- Specified by:
getNumGuardBits
in classQuantizer
- Parameters:
t
- Tile indexc
- Component index- Returns:
- The number of guard bits
-
isReversible
public boolean isReversible(int t, int c)
Returns true if the quantized data is reversible, for the specified tile-component. For the quantized data to be reversible it is necessary and sufficient that the quantization is reversible.- Parameters:
t
- The tile to test for reversibilityc
- The component to test for reversibility- Returns:
- True if the quantized data is reversible, false if not.
-
isDerived
public boolean isDerived(int t, int c)
Returns true if given tile-component uses derived quantization step sizes.
-
getNextCodeBlock
public CBlkWTData getNextCodeBlock(int c, CBlkWTData cblk)
Returns the next code-block in the current tile for the specified component, as a copy (see below). The order in which code-blocks are returned is not specified. However each code-block is returned only once and all code-blocks will be returned if the method is called 'N' times, where 'N' is the number of code-blocks in the tile. After all the code-blocks have been returned for the current tile calls to this method will return 'null'.When changing the current tile (through 'setTile()' or 'nextTile()') this method will always return the first code-block, as if this method was never called before for the new current tile.
The data returned by this method is always a copy of the data. Therfore 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 'CBlkWTData' class.
The 'ulx' and 'uly' members of the returned 'CBlkWTData' object contain the coordinates of the top-left corner of the block, with respect to the tile, not the subband.
- Parameters:
c
- The component for which to return the next code-block.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:
CBlkWTData
-
getNextInternCodeBlock
public final CBlkWTData getNextInternCodeBlock(int c, CBlkWTData cblk)
Returns the next code-block in the current tile for the specified component. The order in which code-blocks are returned is not specified. However each code-block is returned only once and all code-blocks will be returned if the method is called 'N' times, where 'N' is the number of code-blocks in the tile. After all the code-blocks have been returned for the current tile calls to this method will return 'null'.When changing the current tile (through 'setTile()' or 'nextTile()') this method will always return the first code-block, as if this method was never called before for the new current tile.
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 'CBlkWTData' class.
The 'ulx' and 'uly' members of the returned 'CBlkWTData' object contain the coordinates of the top-left corner of the block, with respect to the tile, not the subband.
- Parameters:
c
- The component for which to return the next code-block.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:
CBlkWTData
-
calcSbParams
protected void calcSbParams(SubbandAn sb, 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'.- Specified by:
calcSbParams
in classQuantizer
- Parameters:
sb
- The root of the subband tree.c
- The component index- See Also:
SubbandAn.stepWMSE
-
convertToExpMantissa
public static int convertToExpMantissa(float step)
Converts the floating point value to its exponent-mantissa representation. The mantissa occupies the 11 least significant bits (bits 10-0), and the exponent the previous 5 bits (bits 15-11).- Parameters:
step
- The quantization step, normalized to a dynamic range of 1.- Returns:
- The exponent mantissa representation of the step.
-
getMaxMagBits
public int getMaxMagBits(int c)
Returns the maximum number of magnitude bits in any subband of the current tile.- Specified by:
getMaxMagBits
in classQuantizer
- Parameters:
c
- the component number- Returns:
- The maximum number of magnitude bits in all subbands of the current tile.
-
-