| java.lang.Object
 jj2000.j2k.image.ImgDataAdapter
jj2000.j2k.quantization.quantizer.Quantizer
jj2000.j2k.quantization.quantizer.StdQuantizer
| StdQuantizer | | public class StdQuantizer extends Quantizer (Code) | | 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.
See Also: Subband
See Also: Quantizer |
| Method Summary | |
| protected void | calcSbParams(SubbandAn sb, int c)
Calculates the parameters of the SubbandAn objects that depend on the
Quantizer. | | public static int | convertToExpMantissa(float step)
Converts the floating point value to its exponent-mantissa
representation. | | public int | getMaxMagBits(int c)
Returns the maximum number of magnitude bits in any subband of the
current tile. | | 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). | | final public CBlkWTData | getNextInternCodeBlock(int c, CBlkWTData cblk)
Returns the next code-block in the current tile for the specified
component. | | public int | getNumGuardBits(int t, int c)
Returns the number of guard bits used by this quantizer in the given
tile-component. | | public QuantTypeSpec | getQuantTypeSpec()
Returns the quantization type spec object associated to the quantizer. | | public boolean | isDerived(int t, int c)
Returns true if given tile-component uses derived quantization step
sizes. | | public boolean | isReversible(int t, int c)
Returns true if the quantized data is reversible, for the specified
tile-component. |
| QSTEP_EXPONENT_BITS | | final public static int QSTEP_EXPONENT_BITS(Code) | | The number of exponent bits for the quantization steps
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| QSTEP_MANTISSA_BITS | | final public static int QSTEP_MANTISSA_BITS(Code) | | The number of mantissa bits for the quantization steps
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| QSTEP_MAX_EXPONENT | | final public static int QSTEP_MAX_EXPONENT(Code) | | The maximum value of the exponent for the quantization steps
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| QSTEP_MAX_MANTISSA | | final public static int QSTEP_MAX_MANTISSA(Code) | | The maximum value of the mantissa for the quantization steps
|
| StdQuantizer | | public StdQuantizer(CBlkWTDataSrc src, J2KImageWriteParamJava wp)(Code) | | 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.
Parameters:
encSpec - The encoder specifications |
| calcSbParams | | protected void calcSbParams(SubbandAn sb, int c)(Code) | | 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.
Parameters:
c - The component index
See Also: SubbandAn.stepWMSE |
| convertToExpMantissa | | public static int convertToExpMantissa(float step)(Code) | | 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. The exponent mantissa representation of the step. |
| getMaxMagBits | | public int getMaxMagBits(int c)(Code) | | Returns the maximum number of magnitude bits in any subband of the
current tile.
Parameters:
c - the component number The maximum number of magnitude bits in all subbands of thecurrent tile. |
| getNextCodeBlock | | public CBlkWTData getNextCodeBlock(int c, CBlkWTData cblk)(Code) | | 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.
Parameters:
cblk - If non-null this object will be used to return the newcode-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. The next code-block in the current tile for component 'n', ornull if all code-blocks for the current tile have been returned.
See Also: CBlkWTData |
| getNextInternCodeBlock | | final public CBlkWTData getNextInternCodeBlock(int c, CBlkWTData cblk)(Code) | | 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.
Parameters:
cblk - If non-null this object will be used to return the newcode-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. The next code-block in the current tile for component 'n', ornull if all code-blocks for the current tile have been returned.
See Also: CBlkWTData |
| getNumGuardBits | | public int getNumGuardBits(int t, int c)(Code) | | Returns the number of guard bits used by this quantizer in the given
tile-component.
Parameters:
t - Tile index
Parameters:
c - Component index The number of guard bits |
| getQuantTypeSpec | | public QuantTypeSpec getQuantTypeSpec()(Code) | | Returns the quantization type spec object associated to the quantizer.
The quantization type spec |
| isDerived | | public boolean isDerived(int t, int c)(Code) | | Returns true if given tile-component uses derived quantization step
sizes.
Parameters:
t - Tile index
Parameters:
c - Component index True if derived |
| isReversible | | public boolean isReversible(int t, int c)(Code) | | 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 reversibility
Parameters:
c - The component to test for reversibility True if the quantized data is reversible, false if not. |
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