ucar.jpeg.jj2000.j2k.codestream.reader
Class HeaderDecoder

java.lang.Object
  extended by ucar.jpeg.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:

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
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 ucar.jpeg.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 ucar.jpeg.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 ucar.jpeg.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
HeaderDecoder(RandomAccessIO ehs, ParameterList pl, HeaderInfo hi)
          Creates a HeaderDecoder instance and read in two passes the main header of the codestream.
 
Method Summary
 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:
jj2000.j2k.image.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.


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