| java.lang.Object
 jj2000.j2k.image.ImgDataAdapter
jj2000.j2k.quantization.quantizer.Quantizer
All known Subclasses: jj2000.j2k.quantization.quantizer.StdQuantizer,
| Quantizer | | abstract public class Quantizer extends ImgDataAdapter implements CBlkQuantDataSrcEnc(Code) | | This abstract class provides the general interface for quantizers. The
input of a quantizer is the output of a wavelet transform. The output of
the quantizer is the set of quantized wavelet coefficients represented in
sign-magnitude notation (see below).
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.
See Also: Subband |
| Constructor Summary | |
| public | Quantizer(CBlkWTDataSrc src)
Initializes the source of wavelet transform coefficients. |
| Method Summary | |
| abstract protected void | calcSbParams(SubbandAn sb, int n)
Calculates the parameters of the SubbandAn objects that depend on the
Quantizer. | | public static Quantizer | createInstance(CBlkWTDataSrc src, J2KImageWriteParamJava wp)
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. | | public SubbandAn | getAnSubbandTree(int t, int c)
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().
Parameters:
t - The index of the tile.
Parameters:
c - The index of the component. | | public int | getCbULX()
Returns the horizontal offset of the code-block partition. | | public int | getCbULY()
Returns the vertical offset of the code-block partition. | | abstract public int | getMaxMagBits(int c)
Returns the maximum number of magnitude bits in any subband in the
current tile. | | abstract public int | getNumGuardBits(int t, int c)
Returns the number of guard bits used by this quantizer in the
given tile-component. | | public static String[][] | getParameterInfo()
Returns the parameters that are used in this class and implementing
classes. | | abstract public boolean | isDerived(int t, int c)
Returns true if the quantizer of given tile-component uses derived
quantization step sizes. |
| OPT_PREFIX | | final public static char OPT_PREFIX(Code) | | The prefix for quantizer options: 'Q'
|
| Quantizer | | public Quantizer(CBlkWTDataSrc src)(Code) | | Initializes the source of wavelet transform coefficients.
Parameters:
src - The source of wavelet transform coefficients. |
| calcSbParams | | abstract protected void calcSbParams(SubbandAn sb, int n)(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:
n - The component index.
See Also: SubbandAn.stepWMSE |
| createInstance | | public static Quantizer createInstance(CBlkWTDataSrc src, J2KImageWriteParamJava wp)(Code) | | 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 quantized
Parameters:
encSpec - Encoder specifications
exception:
IllegalArgumentException - If an error occurs while parsingthe options in 'pl' |
| getAnSubbandTree | | public SubbandAn getAnSubbandTree(int t, int c)(Code) | | 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().
Parameters:
t - The index of the tile.
Parameters:
c - The index of the component. The subband tree structure, see SubbandAn.
See Also: SubbandAn
See Also: Subband
See Also: Quantizer.calcSbParams |
| getCbULX | | public int getCbULX()(Code) | | Returns the horizontal offset of the code-block partition. Allowable
values are 0 and 1, nothing else.
|
| getCbULY | | public int getCbULY()(Code) | | Returns the vertical offset of the code-block partition. Allowable
values are 0 and 1, nothing else.
|
| getMaxMagBits | | abstract public int getMaxMagBits(int c)(Code) | | Returns the maximum number of magnitude bits in any subband in the
current tile.
Parameters:
c - the component number The maximum number of magnitude bits in all subbands of thecurrent tile. |
| getNumGuardBits | | abstract 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 |
| getParameterInfo | | public static String[][] getParameterInfo()(Code) | | 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.
the options name, their synopsis and their explanation, or null if no options are supported. |
| isDerived | | abstract public boolean isDerived(int t, int c)(Code) | | Returns true if the quantizer of given tile-component uses derived
quantization step sizes.
Parameters:
t - Tile index
Parameters:
c - Component index True if derived quantization is used. |
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