Class Subband

  • Direct Known Subclasses:
    SubbandAn, SubbandSyn

    public abstract class Subband
    extends Object
    This abstract class represents a subband in a bidirectional tree structure that describes the subband decomposition for a wavelet transform. This class is implemented by the SubbandAn and SubbandSyn classes, which are for the analysis and synthesis sides, respectively.

    The element can be either a node or a leaf of the tree. If it is a node then ther are 4 descendants (LL, HL, LH and HH). If it is a leaf ther are no descendants.

    The tree is bidirectional. Each element in the tree structure has a "parent", which is the subband from which the element was obtained by decomposition. The only exception is the root element which has no parent (i.e.it's null), for obvious reasons.

    See Also:
    SubbandAn, SubbandSyn
    • Field Summary

      Fields 
      Modifier and Type Field Description
      int anGainExp
      The base 2 exponent of the analysis gain of the subband.
      int h
      The height of the subband
      boolean isNode
      True if it is a node in the tree, false if it is a leaf.
      int level
      The level in the tree to which this subband belongs, which is the number of wavelet decompositions performed to produce this subband.
      int nomCBlkH
      The nominal code-block height
      int nomCBlkW
      The nominal code-block width
      Point numCb
      The number of code-blocks (in both directions) contained in this subband.
      int orientation
      The orientation of this subband (WT_ORIENT_LL, WT_ORIENT_HL, WT_ORIENT_LH, WT_ORIENT_HH).
      int resLvl
      The resolution level to which this subband contributes.
      int sbandIdx
      The subband index within its resolution level.
      int ulcx
      The horizontal coordinate of the upper-left corner of the subband, with respect to the canvas origin, in the component's grid and subband's decomposition level.
      int ulcy
      The vertical coordinate of the upper-left corner of the subband, with respect to the canvas origin, in the component's grid and subband's decomposition level.
      int ulx
      The horizontal coordinate of the upper-left corner of the subband
      int uly
      The vertical coordinate of the upper-left corner of the subband
      int w
      The width of the subband
      static int WT_ORIENT_HH
      The ID for the HH orientation
      static int WT_ORIENT_HL
      The ID for the HL (horizontal high-pass) orientation
      static int WT_ORIENT_LH
      The ID for the LH (vertical high-pass) orientation
      static int WT_ORIENT_LL
      The ID for the LL orientation
    • Constructor Summary

      Constructors 
      Constructor Description
      Subband()
      Creates a Subband element with all the default values.
      Subband​(int w, int h, int ulcx, int ulcy, int lvls, WaveletFilter[] hfilters, WaveletFilter[] vfilters)
      Creates the top-level node and the entire subband tree, with the top-level dimensions, the number of decompositions, and the decomposition tree as specified.
    • Field Detail

      • WT_ORIENT_LL

        public static final int WT_ORIENT_LL
        The ID for the LL orientation
        See Also:
        Constant Field Values
      • WT_ORIENT_HL

        public static final int WT_ORIENT_HL
        The ID for the HL (horizontal high-pass) orientation
        See Also:
        Constant Field Values
      • WT_ORIENT_LH

        public static final int WT_ORIENT_LH
        The ID for the LH (vertical high-pass) orientation
        See Also:
        Constant Field Values
      • WT_ORIENT_HH

        public static final int WT_ORIENT_HH
        The ID for the HH orientation
        See Also:
        Constant Field Values
      • isNode

        public boolean isNode
        True if it is a node in the tree, false if it is a leaf. False by default.
      • orientation

        public int orientation
        The orientation of this subband (WT_ORIENT_LL, WT_ORIENT_HL, WT_ORIENT_LH, WT_ORIENT_HH). It is WT_ORIENT_LL by default. The orientation of the top-level node (i.e. the full image before any decomposition) is WT_ORIENT_LL.
      • level

        public int level
        The level in the tree to which this subband belongs, which is the number of wavelet decompositions performed to produce this subband. It is 0 for the top-level (i.e. root) node. It is 0 by default.
      • resLvl

        public int resLvl
        The resolution level to which this subband contributes. Level 0 is the smallest resolution level (the one with the lowest frequency LL subband). It is 0 by default.
      • numCb

        public Point numCb
        The number of code-blocks (in both directions) contained in this subband.
      • anGainExp

        public int anGainExp
        The base 2 exponent of the analysis gain of the subband. The analysis gain of a subband is defined as the gain of the previous subband (i.e. the one from which this one was obtained) multiplied by the line gain and by the column gain. The line (column) gain is the gain of the line (column) filter that was used to obtain it, which is the DC gain for a low-pass filter and the Nyquist gain for a high-pass filter. It is 0 by default.

        Using the base 2 exponent of the value contrains the possible gains to powers of 2. However this is perfectly compatible to the filter normalization policy assumed here. See the split() method for more details.

        See Also:
        split(jj2000.j2k.wavelet.WaveletFilter, jj2000.j2k.wavelet.WaveletFilter)
      • sbandIdx

        public int sbandIdx
        The subband index within its resolution level. This value uniquely identifies a subband within a resolution level and a decomposition level within it. Note that only leaf elements represent "real" subbands, while node elements represent only intermediate stages.

        It is defined recursively. The root node gets a value of 0. For a given node, with a subband index 'b', its LL descendant gets 4*b, its HL descendant 4*b+1, its LH descendant 4*b+2, and its HH descendant 4*b+3, for their subband indexes.

      • ulcx

        public int ulcx
        The horizontal coordinate of the upper-left corner of the subband, with respect to the canvas origin, in the component's grid and subband's decomposition level. This is the real horizontal index of the first column of this subband. If even the horizontal decomposition of this subband should be done with the low-pass-first convention. If odd it should be done with the high-pass-first convention.
      • ulcy

        public int ulcy
        The vertical coordinate of the upper-left corner of the subband, with respect to the canvas origin, in the component's grid and subband's decomposition level. This is the real vertical index of the first column of this subband. If even the vertical decomposition of this subband should be done with the low-pass-first convention. If odd it should be done with the high-pass-first convention.
      • ulx

        public int ulx
        The horizontal coordinate of the upper-left corner of the subband
      • uly

        public int uly
        The vertical coordinate of the upper-left corner of the subband
      • w

        public int w
        The width of the subband
      • h

        public int h
        The height of the subband
      • nomCBlkW

        public int nomCBlkW
        The nominal code-block width
      • nomCBlkH

        public int nomCBlkH
        The nominal code-block height
    • Constructor Detail

      • Subband

        public Subband()
        Creates a Subband element with all the default values. The dimensions are (0,0), the upper left corner is (0,0) and the upper-left corner with respect to the canvas is (0,0) too.
      • Subband

        public Subband​(int w,
                       int h,
                       int ulcx,
                       int ulcy,
                       int lvls,
                       WaveletFilter[] hfilters,
                       WaveletFilter[] vfilters)
        Creates the top-level node and the entire subband tree, with the top-level dimensions, the number of decompositions, and the decomposition tree as specified.

        For the analysis subband gain calculation it is assumed that analysis filters are normalized with a DC gain of 1 and a Nyquist gain of 2.

        This constructor does not initialize the value of the magBits member variable. This variable is normally initialized by the quantizer, on the encoder side, or the bit stream reader, on the decoder side.

        Parameters:
        w - The top-level width
        h - The top-level height
        ulcx - The horizontal coordinate of the upper-left corner with respect to the canvas origin, in the component grid.
        ulcy - The vertical coordinate of the upper-left corner with respect to the canvas origin, in the component grid.
        lvls - The number of levels (or LL decompositions) in the tree.
        hfilters - The horizontal wavelet filters (analysis or synthesis) for each resolution level, starting at resolution level 0. If there are less elements in the array than there are resolution levels, the last element is used for the remaining resolution levels.
        vfilters - The vertical wavelet filters (analysis or synthesis) for each resolution level, starting at resolution level 0. If there are less elements in the array than there are resolution levels, the last element is used for the remaining resolution levels.
        See Also:
        WaveletTransform
    • Method Detail

      • getParent

        public abstract Subband getParent()
        Returns the parent of this subband. The parent of a subband is the subband from which this one was obtained by decomposition. The root element has no parent subband (null).
        Returns:
        The parent subband, or null for the root one.
      • getLL

        public abstract Subband getLL()
        Returns the LL child subband of this subband.
        Returns:
        The LL child subband, or null if there are no childs.
      • getHL

        public abstract Subband getHL()
        Returns the HL (horizontal high-pass) child subband of this subband.
        Returns:
        The HL child subband, or null if there are no childs.
      • getLH

        public abstract Subband getLH()
        Returns the LH (vertical high-pass) child subband of this subband.
        Returns:
        The LH child subband, or null if there are no childs.
      • getHH

        public abstract Subband getHH()
        Returns the HH child subband of this subband.
        Returns:
        The HH child subband, or null if there are no childs.
      • split

        protected abstract Subband split​(WaveletFilter hfilter,
                                         WaveletFilter vfilter)
        Splits the current subband in its four subbands. This creates the four childs (LL, HL, LH and HH) and converts the leaf in a node.
        Parameters:
        hfilter - The horizontal wavelet filter used to decompose this subband.
        vfilter - The vertical wavelet filter used to decompose this subband.
        Returns:
        A reference to the LL leaf (getLL()).
      • initChilds

        protected void initChilds()
        Initializes the childs of this node with the correct values. The sizes of the child subbands are calculated by taking into account the position of the subband in the canvas.

        For the analysis subband gain calculation it is assumed that analysis filters are normalized with a DC gain of 1 and a Nyquist gain of 2.

      • nextSubband

        public Subband nextSubband()
        Returns the next subband in the same resolution level, following the subband index order. If already at the last subband then null is returned. If this subband is not a leaf an IllegalArgumentException is thrown.
        Returns:
        The next subband in the same resolution level, following the subband index order, or null if already at last subband.
      • getNextResLevel

        public Subband getNextResLevel()
        Returns the first leaf subband element in the next higher resolution level.
        Returns:
        The first leaf element in the next higher resolution level, or null if there is no higher resolution level.
      • getSubbandByIdx

        public Subband getSubbandByIdx​(int rl,
                                       int sbi)
        Returns a subband element in the tree, given its resolution level and subband index. This method searches through the tree.
        Parameters:
        rl - The resolution level.
        sbi - The subband index, within the resolution level.
      • getSubband

        public Subband getSubband​(int x,
                                  int y)
        Returns a reference to the Subband element to which the specified point belongs. The specified point must be inside this (i.e. the one defined by this object) subband. This method searches through the tree.
        Parameters:
        x - horizontal coordinate of the specified point.
        y - horizontal coordinate of the specified point.
      • toString

        public String toString()
        Returns subband informations in a string.
        Overrides:
        toString in class Object
        Returns:
        Subband informations
      • getHorWFilter

        public abstract WaveletFilter getHorWFilter()
        This function returns the horizontal wavelet filter relevant to this subband
        Returns:
        The horizontal wavelet filter
      • getVerWFilter

        public abstract WaveletFilter getVerWFilter()
        This function returns the vertical wavelet filter relevant to this subband
        Returns:
        The vertical wavelet filter