Class ForwCompTransf

java.lang.Object
jj2000.j2k.image.ImgDataAdapter
jj2000.j2k.image.forwcomptransf.ForwCompTransf
All Implemented Interfaces:
BlkImgDataSrc, ImgData

public class ForwCompTransf extends ImgDataAdapter implements BlkImgDataSrc
This class apply component transformations to the tiles depending on user specifications. These transformations can be used to improve compression efficiency but are not related to colour transforms used to map colour values for display purposes. JPEG 2000 part I defines 2 component transformations: RCT (Reversible Component Transformation) and ICT (Irreversible Component Transformation).
See Also:
  • Field Details

    • NONE

      public static final int NONE
      Identifier for no component transformation. Value is 0.
      See Also:
    • FORW_RCT

      public static final int FORW_RCT
      Identifier for the Forward Reversible Component Transformation (FORW_RCT). Value is 1.
      See Also:
    • FORW_ICT

      public static final int FORW_ICT
      Identifier for the Forward Irreversible Component Transformation (FORW_ICT). Value is 2
      See Also:
    • OPT_PREFIX

      public static final char OPT_PREFIX
      The prefix for component transformation type: 'M'
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  • Constructor Details

    • ForwCompTransf

      public ForwCompTransf(BlkImgDataSrc imgSrc, J2KImageWriteParamJava wp)
      Constructs a new ForwCompTransf object that operates on the specified source of image data.
      Parameters:
      imgSrc - The source from where to get the data to be transformed
      wp - The encoder specifications
      See Also:
  • Method Details

    • getFixedPoint

      public int getFixedPoint(int c)
      Returns the position of the fixed point in the specified component. This is the position of the least significant integral (i.e. non-fractional) bit, which is equivalent to the number of fractional bits. For instance, for fixed-point values with 2 fractional bits, 2 is returned. For floating-point data this value does not apply and 0 should be returned. Position 0 is the position of the least significant bit in the data.

      This default implementation assumes that the number of fractional bits is not modified by the component mixer.

      Specified by:
      getFixedPoint in interface BlkImgDataSrc
      Parameters:
      c - The index of the component.
      Returns:
      The value of the fixed point position of the source since the color transform does not affect it.
    • getParameterInfo

      public static String[][] getParameterInfo()
      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 4 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.
      Returns:
      the options name, their synopsis and their explanation, or null if no options are supported.
    • calcMixedBitDepths

      public static int[] calcMixedBitDepths(int[] ntdepth, int ttype, int[] tdepth)
      Calculates the bitdepths of the transformed components, given the bitdepth of the un-transformed components and the component tranformation type.
      Parameters:
      ntdepth - The bitdepth of each non-transformed components.
      ttype - The type ID of the component transformation.
      tdepth - If not null the results are stored in this array, otherwise a new array is allocated and returned.
      Returns:
      The bitdepth of each transformed component.
    • toString

      public String toString()
      Returns a string with a descriptive text of which forward component transformation is used. This can be either "Forward RCT" or "Forward ICT" or "No component transformation" depending on the current tile.
      Overrides:
      toString in class Object
      Returns:
      A descriptive string
    • getNomRangeBits

      public int getNomRangeBits(int c)
      Returns the number of bits, referred to as the "range bits", corresponding to the nominal range of the data in the specified component and in the current tile. If this number is b then for unsigned data the nominal range is between 0 and 2^b-1, and for signed data it is between -2^(b-1) and 2^(b-1)-1. Note that this value can be affected by the multiple component transform.
      Specified by:
      getNomRangeBits in interface ImgData
      Overrides:
      getNomRangeBits in class ImgDataAdapter
      Parameters:
      c - The index of the component.
      Returns:
      The bitdepth of component 'c' after mixing.
    • isReversible

      public boolean isReversible()
      Returns true if this transform is reversible in current tile. Reversible component transformations are those which operation can be completely reversed without any loss of information (not even due to rounding).
      Returns:
      Reversibility of component transformation in current tile
    • getCompData

      public DataBlk getCompData(DataBlk blk, int c)
      Apply forward component transformation associated with the current tile. If no component transformation has been requested by the user, data are not modified.

      This method calls the getInternCompData() method, but respects the definitions of the getCompData() method defined in the BlkImgDataSrc interface.

      Specified by:
      getCompData in interface BlkImgDataSrc
      Parameters:
      blk - Determines the rectangular area to return, and the data is returned in this object.
      c - Index of the output component.
      Returns:
      The requested DataBlk
      See Also:
    • getInternCompData

      public DataBlk getInternCompData(DataBlk blk, int c)
      Apply the component transformation associated with the current tile. If no component transformation has been requested by the user, data are not modified. Else, appropriate method is called (forwRCT or forwICT).
      Specified by:
      getInternCompData in interface BlkImgDataSrc
      Parameters:
      blk - Determines the rectangular area to return.
      c - Index of the output component.
      Returns:
      The requested DataBlk
      See Also:
      • forwRCT(jj2000.j2k.image.DataBlk, int)
      • forwICT(jj2000.j2k.image.DataBlk, int)
    • setTile

      public void setTile(int x, int y)
      Changes the current tile, given the new indexes. An IllegalArgumentException is thrown if the indexes do not correspond to a valid tile.

      This default implementation changes the tile in the source and re-initializes properly component transformation variables..

      Specified by:
      setTile in interface ImgData
      Overrides:
      setTile in class ImgDataAdapter
      Parameters:
      x - The horizontal index of the tile.
      y - The vertical index of the new tile.
    • nextTile

      public void nextTile()
      Advances to the next tile, in standard scan-line order (by rows then columns). An NoNextElementException is thrown if the current tile is the last one (i.e. there is no next tile).

      This default implementation just advances to the next tile in the source and re-initializes properly component transformation variables.

      Specified by:
      nextTile in interface ImgData
      Overrides:
      nextTile in class ImgDataAdapter