HeaderDecoder (Unidata jj2000 5.2 API)

java.lang.Object
- jj2000.j2k.codestream.reader.HeaderDecoder

All Implemented Interfaces:

Markers, ProgressionType, StdEntropyCoderOptions
```
public class HeaderDecoder
extends Object
implements ProgressionType, Markers, StdEntropyCoderOptions
```
This class reads main and tile-part headers from the codestream given a RandomAccessIO instance located at the beginning of the codestream (i.e just before the SOC marker) or at the beginning of a tile-part (i.e. just before a SOT marker segment) respectively.
A marker segment includes a marker and eventually marker segment parameters. It is designed by the three letters code of the marker associated with the marker segment. JPEG 2000 part 1 defines 6 types of markers segments:
- Delimiting : SOC, SOT, SOD, EOC
- Fixed information: SIZ.
- Functional: COD, COC, RGN, QCD, QCC,POC.
- In bit-stream: SOP, EPH.
- Pointer: TLM, PLM, PLT, PPM, PPT.
- Informational: CRG, COM.
The main header is read when the constructor is called whereas tile-part headers are read when the FileBitstreamReaderAgent instance is created. The reading is done in 2 passes:
1. All marker segments are buffered and their corresponding flag is activated (extractMainMarkSeg and extractTilePartMarkSeg methods).
2. Buffered marker segment are analyzed in a logical way and specifications are stored in appropriate member of DecoderSpecs instance (readFoundMainMarkSeg and readFoundTilePartMarkSeg methods).
Whenever a marker segment is not recognized a warning message is displayed and its length parameter is used to skip it.

The information found in this header is stored in HeaderInfo and DecoderSpecs instances.
See Also:
DecoderSpecs, HeaderInfo, Decoder, FileBitstreamReaderAgent

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`CRG_FOUND` Flag bit for CRG marker segment found
`int`	`mainHeadOff` The offset of the main header in the input stream
`int[]`	`nTileParts` The number of tile parts in each tile
`static char`	`OPT_PREFIX` The prefix for header decoder options: 'H'
`static int`	`PPM_FOUND` Flag bit for SOD marker segment found
`static int`	`PPT_FOUND` Flag bit for SOD marker segment found
`static int`	`SOD_FOUND` Flag bit for SOD marker segment found
`Vector`	`tileOfTileParts` Vector containing info as to which tile each tilepart belong

Fields inherited from interface jj2000.j2k.codestream.ProgressionType
COMP_POS_RES_LY_PROG, LY_RES_COMP_POS_PROG, POS_COMP_RES_LY_PROG, RES_LY_COMP_POS_PROG, RES_POS_COMP_LY_PROG

Fields inherited from interface jj2000.j2k.codestream.Markers
COC, COD, COM, CRG, EOC, EPH, EPH_LENGTH, ERS_SEG_SYMBOLS, ERS_SOP, MAX_COMP_BITDEPTH, MAX_LPPM, MAX_LPPT, PLM, PLT, POC, PPM, PPT, PRECINCT_PARTITION_DEF_SIZE, QCC, QCD, RCOM_GEN_USE, RGN, RSIZ_BASELINE, RSIZ_ER_FLAG, RSIZ_ROI, SCOX_HOR_CB_PART, SCOX_PRECINCT_PARTITION, SCOX_USE_EPH, SCOX_USE_SOP, SCOX_VER_CB_PART, SIZ, SOC, SOD, SOP, SOP_LENGTH, SOT, SQCX_EXP_MASK, SQCX_EXP_SHIFT, SQCX_GB_MSK, SQCX_GB_SHIFT, SQCX_NO_QUANTIZATION, SQCX_SCALAR_DERIVED, SQCX_SCALAR_EXPOUNDED, SRGN_IMPLICIT, SSIZ_DEPTH_BITS, TLM

Fields inherited from interface jj2000.j2k.entropy.StdEntropyCoderOptions
FIRST_BYPASS_PASS_IDX, MAX_CB_AREA, MAX_CB_DIM, MIN_CB_DIM, NUM_EMPTY_PASSES_IN_MS_BP, NUM_NON_BYPASS_MS_BP, NUM_PASSES, OPT_BYPASS, OPT_PRED_TERM, OPT_RESET_MQ, OPT_SEG_SYMBOLS, OPT_TERM_PASS, OPT_VERT_STR_CAUSAL, STRIPE_HEIGHT

Constructor Summary

Constructors
Constructor and Description
`HeaderDecoder(RandomAccessIO ehs, ParameterList pl, HeaderInfo hi)` Creates a HeaderDecoder instance and read in two passes the main header of the codestream.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`checkMarkerLength(DataInputStream ehs, String str)` Checks that the marker segment length is correct.
`BlkImgDataSrc`	`createChannelDefinitionMapper(BlkImgDataSrc src, ColorSpace csMap)` Creates and returns the ChannelDefinitonMapper which maps the input channels to the channel definition for the appropriate colorspace.
`BlkImgDataSrc`	`createColorSpaceMapper(BlkImgDataSrc src, ColorSpace csMap)` Creates and returns the EnumeratedColorSpaceMapper corresponding to the information read from the JP2 image file via the ColorSpace parameter.
`Dequantizer`	`createDequantizer(CBlkQuantDataSrcDec src, int[] rb, DecoderSpecs decSpec2)` Returns the dequantizer parameters.
`EntropyDecoder`	`createEntropyDecoder(CodedCBlkDataSrcDec src, ParameterList pl)` Creates and returns the entropy decoder corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
`BlkImgDataSrc`	`createPalettizedColorSpaceMapper(BlkImgDataSrc src, ColorSpace csMap)` Creates and returns the PalettizedColorSpaceMapper which uses the input samples as indicies into a sample palette to construct the output.
`BlkImgDataSrc`	`createResampler(BlkImgDataSrc src, ColorSpace csMap)` Creates and returns the Resampler which converts the input source to one in which all channels have the same number of samples.
`ROIDeScaler`	`createROIDeScaler(CBlkQuantDataSrcDec src, ParameterList pl, DecoderSpecs decSpec2)` Creates and returns the ROIDeScaler corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
`void`	`extractTilePartMarkSeg(short marker, RandomAccessIO ehs, int tileIdx, int tilePartIdx)` This method extracts a marker segment in a tile-part header and stores it into a byte buffer for the second pass.
`int`	`getCbULX()` Returns the horizontal code-block partition origin.Allowable values are 0 and 1, nothing else.
`int`	`getCbULY()` Returns the vertical code-block partition origin.
`int`	`getCompSubsX(int c)` Returns the component sub-sampling factor, with respect to the reference grid, along the horizontal direction for the specified component.
`int`	`getCompSubsY(int c)` Returns the component sub-sampling factor, with respect to the reference grid, along the vertical direction for the specified component.
`DecoderSpecs`	`getDecoderSpecs()` Return the DecoderSpecs instance filled when reading the headers
`int`	`getImgHeight()` Returns the image height in the reference grid.
`int`	`getImgULX()` Return the horizontal upper-left coordinate of the image in the reference grid.
`int`	`getImgULY()` Return the vertical upper-left coordinate of the image in the reference grid.
`int`	`getImgWidth()` Returns the image width in the reference grid.
`int`	`getMaxCompImgHeight()` Return the maximum height among all components
`int`	`getMaxCompImgWidth()` Return the maximum width among all components
`int`	`getNomTileHeight()` Returns the nominal width of the tiles in the reference grid.
`int`	`getNomTileWidth()` Returns the nominal width of the tiles in the reference grid.
`int`	`getNumComps()` Returns the number of components in the image.
`int`	`getNumFoundMarkSeg()` Returns the number of found marker segments in the current header.
`int`	`getNumTiles()` Return the number of tiles in the image
`int`	`getOriginalBitDepth(int c)` Returns the original bitdepth of the specified component.
`ByteArrayInputStream`	`getPackedPktHead(int tile)` Return the packed packet headers for a given tile.
`static String[][]`	`getParameterInfo()` Returns the parameters that are used in this class.
`int`	`getPPX(int t, int c, int rl)` Returns the precinct partition width for the specified tile-component and resolution level.
`int`	`getPPY(int t, int c, int rl)` Returns the precinct partition height for the specified tile-component and resolution level.
`Coord`	`getTilingOrigin(Coord co)` Returns the tiling origin, referred to as '(Px,Py)' in the 'ImgData' interface.
`boolean`	`isOriginalSigned(int c)` Returns true if the original data of the specified component was signed.
`boolean`	`precinctPartitionUsed()` Returns the boolean used to know if the precinct partition is used
`void`	`readFoundTilePartMarkSeg(int tileIdx, int tpIdx)` Retrieves and reads all marker segments previously found in the tile-part header.
`void`	`resetHeaderMarkers()` Method that resets members indicating which markers have already been found
`void`	`setTileOfTileParts(int tile)` Sets the tile of each tile part in order.
`String`	`toString()` Print information about the current header.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - OPT_PREFIX
```
public static final char OPT_PREFIX
```
    The prefix for header decoder options: 'H'
    
    See Also:
    Constant Field Values
  - nTileParts
```
public int[] nTileParts
```
    The number of tile parts in each tile
  - SOD_FOUND
```
public static final int SOD_FOUND
```
    Flag bit for SOD marker segment found
    
    See Also:
    Constant Field Values
  - PPM_FOUND
```
public static final int PPM_FOUND
```
    Flag bit for SOD marker segment found
    
    See Also:
    Constant Field Values
  - PPT_FOUND
```
public static final int PPT_FOUND
```
    Flag bit for SOD marker segment found
    
    See Also:
    Constant Field Values
  - CRG_FOUND
```
public static final int CRG_FOUND
```
    Flag bit for CRG marker segment found
    
    See Also:
    Constant Field Values
  - mainHeadOff
```
public int mainHeadOff
```
    The offset of the main header in the input stream
  - tileOfTileParts
```
public Vector tileOfTileParts
```
    Vector containing info as to which tile each tilepart belong
- Constructor Detail
  - HeaderDecoder
```
public HeaderDecoder(RandomAccessIO ehs,
             ParameterList pl,
             HeaderInfo hi)
              throws IOException
```
    Creates a HeaderDecoder instance and read in two passes the main header of the codestream. The first and last marker segments shall be respectively SOC and SOT.
    
    Parameters:
    ehs - The encoded header stream where marker segments are extracted.
    pl - The ParameterList object of the decoder
    hi - The HeaderInfo holding information found in marker segments
    
    Throws:
    
    IOException - If an I/O error occurs while reading from the encoded header stream.
    
    EOFException - If the end of the encoded header stream is reached before getting all the data.
    
    CorruptedCodestreamException - If invalid data is found in the codestream main header.
- Method Detail
  - getMaxCompImgHeight
```
public int getMaxCompImgHeight()
```
    Return the maximum height among all components
    
    Returns:
    Maximum component height
  - getMaxCompImgWidth
```
public int getMaxCompImgWidth()
```
    Return the maximum width among all components
    
    Returns:
    Maximum component width
  - getImgWidth
```
public final int getImgWidth()
```
    Returns the image width in the reference grid.
    
    Returns:
    The image width in the reference grid
  - getImgHeight
```
public final int getImgHeight()
```
    Returns the image height in the reference grid.
    
    Returns:
    The image height in the reference grid
  - getImgULX
```
public final int getImgULX()
```
    Return the horizontal upper-left coordinate of the image in the reference grid.
    
    Returns:
    The horizontal coordinate of the image origin.
  - getImgULY
```
public final int getImgULY()
```
    Return the vertical upper-left coordinate of the image in the reference grid.
    
    Returns:
    The vertical coordinate of the image origin.
  - getNomTileWidth
```
public final int getNomTileWidth()
```
    Returns the nominal width of the tiles in the reference grid.
    
    Returns:
    The nominal tile width, in the reference grid.
  - getNomTileHeight
```
public final int getNomTileHeight()
```
    Returns the nominal width of the tiles in the reference grid.
    
    Returns:
    The nominal tile width, in the reference grid.
  - getTilingOrigin
```
public final Coord getTilingOrigin(Coord co)
```
    Returns the tiling origin, referred to as '(Px,Py)' in the 'ImgData' interface.
    
    Parameters:
    co - If not null this object is used to return the information. If null a new one is created and returned.
    
    Returns:
    The coordinate of the tiling origin, in the canvas system, on the reference grid.
    See Also:
    ImgData
  - isOriginalSigned
```
public final boolean isOriginalSigned(int c)
```
    Returns true if the original data of the specified component was signed. If the data was not signed a level shift has to be applied at the end of the decompression chain.
    
    Parameters:
    c - The index of the component
    
    Returns:
    True if the original image component was signed.
  - getOriginalBitDepth
```
public final int getOriginalBitDepth(int c)
```
    Returns the original bitdepth of the specified component.
    
    Parameters:
    c - The index of the component
    
    Returns:
    The bitdepth of the component
  - getNumComps
```
public final int getNumComps()
```
    Returns the number of components in the image.
    
    Returns:
    The number of components in the image.
  - getCompSubsX
```
public final int getCompSubsX(int c)
```
    Returns the component sub-sampling factor, with respect to the reference grid, along the horizontal direction for the specified component.
    
    Parameters:
    c - The index of the component
    
    Returns:
    The component sub-sampling factor X-wise.
  - getCompSubsY
```
public final int getCompSubsY(int c)
```
    Returns the component sub-sampling factor, with respect to the reference grid, along the vertical direction for the specified component.
    
    Parameters:
    c - The index of the component
    
    Returns:
    The component sub-sampling factor Y-wise.
  - createDequantizer
```
public final Dequantizer createDequantizer(CBlkQuantDataSrcDec src,
                            int[] rb,
                            DecoderSpecs decSpec2)
```
    Returns the dequantizer parameters. Dequantizer parameters normally are the quantization step sizes, see DequantizerParams.
    
    Parameters:
    src - The source of data for the dequantizer.
    rb - The number of range bits for each component. Must be the number of range bits of the mixed components.
    decSpec2 - The DecoderSpecs instance after any image manipulation.
    
    Returns:
    The dequantizer
  - getCbULX
```
public final int getCbULX()
```
    Returns the horizontal code-block partition origin.Allowable values are 0 and 1, nothing else.
  - getCbULY
```
public final int getCbULY()
```
    Returns the vertical code-block partition origin. Allowable values are 0 and 1, nothing else.
  - getPPX
```
public final int getPPX(int t,
         int c,
         int rl)
```
    Returns the precinct partition width for the specified tile-component and resolution level.
    
    Parameters:
    c - the component index
    t - the tile index
    rl - the resolution level
    
    Returns:
    The precinct partition width for the specified tile-component and resolution level
  - getPPY
```
public final int getPPY(int t,
         int c,
         int rl)
```
    Returns the precinct partition height for the specified tile-component and resolution level.
    
    Parameters:
    c - the component index
    t - the tile index
    rl - the resolution level
    
    Returns:
    The precinct partition height for the specified tile-component and resolution level
  - precinctPartitionUsed
```
public final boolean precinctPartitionUsed()
```
    Returns the boolean used to know if the precinct partition is used
  - checkMarkerLength
```
public void checkMarkerLength(DataInputStream ehs,
                     String str)
                       throws IOException
```
    Checks that the marker segment length is correct.
    
    Parameters:
    ehs - The encoded header stream
    str - The string identifying the marker, such as "SIZ marker"
    
    Throws:
    
    IOException - If an I/O error occurs
  - extractTilePartMarkSeg
```
public void extractTilePartMarkSeg(short marker,
                          RandomAccessIO ehs,
                          int tileIdx,
                          int tilePartIdx)
                            throws IOException
```
    This method extracts a marker segment in a tile-part header and stores it into a byte buffer for the second pass. The marker is first recognized, then its flag is activated and, finally, its content is buffered in an element of byte arrays accessible thanks to a hashTable. If a marker segment is not recognized, it prints a warning and skip it according to its length.
    
    Parameters:
    marker - The marker to process
    ehs - The encoded header stream
    tileIdx - The index of the current tile
    tilePartIdx - The index of the current tile part
    
    Throws:
    
    IOException
  - readFoundTilePartMarkSeg
```
public void readFoundTilePartMarkSeg(int tileIdx,
                            int tpIdx)
                              throws IOException
```
    Retrieves and reads all marker segments previously found in the tile-part header.
    
    Parameters:
    tileIdx - The index of the current tile
    tpIdx - Index of the current tile-part
    
    Throws:
    
    IOException
  - getDecoderSpecs
```
public DecoderSpecs getDecoderSpecs()
```
    Return the DecoderSpecs instance filled when reading the headers
    
    Returns:
    The DecoderSpecs of the decoder
  - createEntropyDecoder
```
public EntropyDecoder createEntropyDecoder(CodedCBlkDataSrcDec src,
                                  ParameterList pl)
```
    Creates and returns the entropy decoder corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    pl - The parameter list containing parameters applicable to the entropy decoder (other parameters can also be present).
    
    Returns:
    The entropy decoder
  - createColorSpaceMapper
```
public BlkImgDataSrc createColorSpaceMapper(BlkImgDataSrc src,
                                   ColorSpace csMap)
                                     throws IOException,
                                            ICCProfileException,
                                            ColorSpaceException
```
    Creates and returns the EnumeratedColorSpaceMapper corresponding to the information read from the JP2 image file via the ColorSpace parameter.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    csMap - provides color space information from the image file
    
    Returns:
    The color space mapping object
    
    Throws:
    
    IOException - image access exception
    
    ICCProfileException - if image contains a bad icc profile
    
    ColorSpaceException - if image contains a bad colorspace box
  - createChannelDefinitionMapper
```
public BlkImgDataSrc createChannelDefinitionMapper(BlkImgDataSrc src,
                                          ColorSpace csMap)
                                            throws IOException,
                                                   ColorSpaceException
```
    Creates and returns the ChannelDefinitonMapper which maps the input channels to the channel definition for the appropriate colorspace.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    csMap - provides color space information from the image file
    
    Returns:
    The channel definition mapping object
    
    Throws:
    
    IOException - image access exception
    
    ColorSpaceException - if image contains a bad colorspace box
  - createPalettizedColorSpaceMapper
```
public BlkImgDataSrc createPalettizedColorSpaceMapper(BlkImgDataSrc src,
                                             ColorSpace csMap)
                                               throws IOException,
                                                      ColorSpaceException
```
    Creates and returns the PalettizedColorSpaceMapper which uses the input samples as indicies into a sample palette to construct the output.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    csMap - provides color space information from the image file
    
    Returns:
    a PalettizedColorSpaceMapper instance
    
    Throws:
    
    IOException - image access exception
    
    ColorSpaceException - if image contains a bad colorspace box
  - createResampler
```
public BlkImgDataSrc createResampler(BlkImgDataSrc src,
                            ColorSpace csMap)
                              throws IOException,
                                     ColorSpaceException
```
    Creates and returns the Resampler which converts the input source to one in which all channels have the same number of samples. This is required for colorspace conversions.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    csMap - provides color space information from the image file
    
    Returns:
    The resampled BlkImgDataSrc
    
    Throws:
    
    IOException - image access exception
    
    ColorSpaceException - if image contains a bad colorspace box
  - createROIDeScaler
```
public ROIDeScaler createROIDeScaler(CBlkQuantDataSrcDec src,
                            ParameterList pl,
                            DecoderSpecs decSpec2)
```
    Creates and returns the ROIDeScaler corresponding to the information read from the codestream header and with the special additional parameters from the parameter list.
    
    Parameters:
    src - The bit stream reader agent where to get code-block data from.
    pl - The parameter list containing parameters applicable to the entropy decoder (other parameters can also be present).
    decSpec2 - The DecoderSpecs instance after any image manipulation.
    
    Returns:
    The ROI descaler.
  - resetHeaderMarkers
```
public void resetHeaderMarkers()
```
    Method that resets members indicating which markers have already been found
  - toString
```
public String toString()
```
    Print information about the current header.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    Information in a String
  - getParameterInfo
```
public static String[][] getParameterInfo()
```
    Returns the parameters that are used in this class. 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 and the third one is a long description of what the parameter is. The synopsis or description may be 'null', in which case it is assumed that there is no synopsis or description of the option, respectively.
    
    Returns:
    the options name, their synopsis and their explanation.
  - getNumTiles
```
public int getNumTiles()
```
    Return the number of tiles in the image
    
    Returns:
    The number of tiles
  - getPackedPktHead
```
public ByteArrayInputStream getPackedPktHead(int tile)
                                      throws IOException
```
    Return the packed packet headers for a given tile.
    
    Returns:
    An input stream containing the packed packet headers for a particular tile
    
    Throws:
    
    IOException - If an I/O error occurs while reading from the encoder header stream
  - setTileOfTileParts
```
public void setTileOfTileParts(int tile)
```
    Sets the tile of each tile part in order. This information is needed for identifying which packet header belongs to which tile when using the PPM marker.
    
    Parameters:
    tile - The tile number that the present tile part belongs to.
  - getNumFoundMarkSeg
```
public int getNumFoundMarkSeg()
```
    Returns the number of found marker segments in the current header.
    
    Returns:
    The number of marker segments found in the current header.

Class HeaderDecoder

Field Summary

Fields inherited from interface jj2000.j2k.codestream.ProgressionType

Fields inherited from interface jj2000.j2k.codestream.Markers

Fields inherited from interface jj2000.j2k.entropy.StdEntropyCoderOptions

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

OPT_PREFIX

nTileParts

SOD_FOUND

PPM_FOUND

PPT_FOUND

CRG_FOUND

mainHeadOff

tileOfTileParts

Constructor Detail

HeaderDecoder

Method Detail

getMaxCompImgHeight

getMaxCompImgWidth

getImgWidth

getImgHeight

getImgULX

getImgULY

getNomTileWidth

getNomTileHeight

getTilingOrigin

isOriginalSigned

getOriginalBitDepth

getNumComps

getCompSubsX

getCompSubsY

createDequantizer

getCbULX

getCbULY

getPPX

getPPY

precinctPartitionUsed

checkMarkerLength

extractTilePartMarkSeg

readFoundTilePartMarkSeg

getDecoderSpecs

createEntropyDecoder

createColorSpaceMapper

createChannelDefinitionMapper

createPalettizedColorSpaceMapper

createResampler

createROIDeScaler

resetHeaderMarkers

toString

getParameterInfo

getNumTiles

getPackedPktHead

setTileOfTileParts

getNumFoundMarkSeg