Class HeaderEncoder

java.lang.Object
jj2000.j2k.codestream.writer.HeaderEncoder
All Implemented Interfaces:
Markers, StdEntropyCoderOptions

public class HeaderEncoder extends Object implements Markers, StdEntropyCoderOptions
This class writes almost of the markers and marker segments in main header and in tile-part headers. It is created by the run() method of the Encoder instance.

A marker segment includes a marker and eventually marker segment parameters. It is designed by the three letter code of the marker associated with the marker segment. JPEG 2000 part I defines 6 types of markers:

  • Delimiting : SOC,SOT,SOD,EOC (written in FileCodestreamWriter).
  • Fixed information: SIZ.
  • Functional: COD,COC,RGN,QCD,QCC,POC.
  • In bit-stream: SOP,EPH.
  • Pointer: TLM,PLM,PLT,PPM,PPT.
  • Informational: CRG,COM.

Main Header is written when Encoder instance calls encodeMainHeader whereas tile-part headers are written when the EBCOTRateAllocator instance calls encodeTilePartHeader.

See Also:
  • Field Details

    • nComp

      protected int nComp
      The number of components in the image
    • baos

      protected ByteArrayOutputStream baos
      The ByteArrayOutputStream to store header data. This handler is kept in order to use methods not accessible from a general DataOutputStream. For the other methods, it's better to use variable hbuf.
      See Also:
    • hbuf

      protected DataOutputStream hbuf
      The DataOutputStream to store header data. This kind of object is useful to write short, int, .... It's constructor takes baos as parameter.
      See Also:
    • origSrc

      protected ImgData origSrc
      The image data reader. Source of original data info
    • isOrigSig

      protected boolean[] isOrigSig
      An array specifying, for each component,if the data was signed or not
    • ralloc

      protected PostCompRateAllocator ralloc
      Reference to the rate allocator
    • dwt

      protected ForwardWT dwt
      Reference to the DWT module
    • tiler

      protected Tiler tiler
      Reference to the tiler module
    • roiSc

      protected ROIScaler roiSc
      Reference to the ROI module
    • wp

      protected J2KImageWriteParamJava wp
      The encoder specifications
  • Constructor Details

    • HeaderEncoder

      public HeaderEncoder(ImgData origsrc, boolean[] isorigsig, ForwardWT dwt, Tiler tiler, J2KImageWriteParamJava wp, ROIScaler roiSc, PostCompRateAllocator ralloc)
      Initializes the header writer with the references to the coding chain.
      Parameters:
      origsrc - The original image data (before any component mixing, tiling, etc.)
      isorigsig - An array specifying for each component if it was originally signed or not.
      dwt - The discrete wavelet transform module.
      tiler - The tiler module.
      wp - The encoder specifications
      roiSc - The ROI scaler module.
      ralloc - The post compression rate allocator.
  • Method Details

    • reset

      public void reset()
      Resets the contents of this HeaderEncoder to its initial state. It erases all the data in the header buffer and reactualizes the headerLength field of the bit stream writer.
    • getBuffer

      protected byte[] getBuffer()
      Returns the byte-buffer used to store the codestream header.
      Returns:
      A byte array countaining codestream header
    • getLength

      public int getLength()
      Returns the length of the header.
      Returns:
      The length of the header in bytes
    • writeTo

      public void writeTo(BinaryDataOutput out) throws IOException
      Writes the header to the specified BinaryDataOutput.
      Parameters:
      out - Where to write the header.
      Throws:
      IOException
    • getBufferLength

      protected int getBufferLength()
      Returns the number of bytes used in the codestream header's buffer.
      Returns:
      Header length in buffer (without any header overhead)
    • writeTo

      public void writeTo(OutputStream out) throws IOException
      Writes the header to the specified OutputStream.
      Parameters:
      out - Where to write the header.
      Throws:
      IOException
    • writeCOD

      protected void writeCOD(boolean mh, int tileIdx) throws IOException
      Writes COD marker segment. COD is a functional marker segment containing the code style default (coding style, decomposition, layering) used for compressing all the components in an image.

      The values can be overriden for an individual component by a COC marker in either the main or the tile header.

      Parameters:
      mh - Flag indicating whether this marker belongs to the main header
      tileIdx - Tile index if the marker belongs to a tile-part header
      Throws:
      IOException
      See Also:
    • writeCOC

      protected void writeCOC(boolean mh, int tileIdx, int compIdx) throws IOException
      Writes COC marker segment . It is a functional marker containing the coding style for one component (coding style, decomposition, layering).

      Its values overrides any value previously set in COD in the main header or in the tile header.

      Parameters:
      mh - Flag indicating whether the main header is to be written
      tileIdx - Tile index
      compIdx - index of the component which need use of the COC marker segment.
      Throws:
      IOException
      See Also:
    • writeMainQCD

      protected void writeMainQCD() throws IOException
      Writes QCD marker segment in main header. QCD is a functional marker segment countaining the quantization default used for compressing all the components in an image. The values can be overriden for an individual component by a QCC marker in either the main or the tile header.
      Throws:
      IOException
    • writeMainQCC

      protected void writeMainQCC(int compIdx) throws IOException
      Writes QCC marker segment in main header. It is a functional marker segment countaining the quantization used for compressing the specified component in an image. The values override for the specified component what was defined by a QCC marker in either the main or the tile header.
      Parameters:
      compIdx - Index of the component which needs QCC marker segment.
      Throws:
      IOException
    • writeTileQCD

      protected void writeTileQCD(int tIdx) throws IOException
      Writes QCD marker segment in tile header. QCD is a functional marker segment countaining the quantization default used for compressing all the components in an image. The values can be overriden for an individual component by a QCC marker in either the main or the tile header.
      Parameters:
      tIdx - Tile index
      Throws:
      IOException
    • writeTileQCC

      protected void writeTileQCC(int t, int compIdx) throws IOException
      Writes QCC marker segment in tile header. It is a functional marker segment countaining the quantization used for compressing the specified component in an image. The values override for the specified component what was defined by a QCC marker in either the main or the tile header.
      Parameters:
      t - Tile index
      compIdx - Index of the component which needs QCC marker segment.
      Throws:
      IOException
    • writePOC

      protected void writePOC(boolean mh, int tileIdx) throws IOException
      Writes POC marker segment. POC is a functional marker segment containing the bounds and progression order for any progression order other than default in the codestream.
      Parameters:
      mh - Flag indicating whether the main header is to be written
      tileIdx - Tile index
      Throws:
      IOException
    • encodeMainHeader

      public void encodeMainHeader() throws IOException
      Write main header. JJ2000 main header corresponds to the following sequence of marker segments:
      1. SOC
      2. SIZ
      3. COD
      4. COC (if needed)
      5. QCD
      6. QCC (if needed)
      7. POC (if needed)
      Throws:
      IOException
    • encodeTilePartHeader

      public void encodeTilePartHeader(int tileLength, int tileIdx) throws IOException
      Writes tile-part header. JJ2000 tile-part header corresponds to the following sequence of marker segments:
      1. SOT
      2. COD (if needed)
      3. COC (if needed)
      4. QCD (if needed)
      5. QCC (if needed)
      6. RGN (if needed)
      7. POC (if needed)
      8. SOD
      Parameters:
      tileLength - The length of the current tile-part.
      tileIdx - Index of the tile to write
      Throws:
      IOException