subband.java

jpeg2000算法实现

     * 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.
     * */
    public Subband() {
    }

    /**
     * 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.
     *
     * <P>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.
     *
     * <P>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.
     *
     * @param w The top-level width
     *
     * @param h The top-level height
     *
     * @param ulcx The horizontal coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param ulcy The vertical coordinate of the upper-left corner with
     * respect to the canvas origin, in the component grid.
     *
     * @param lvls The number of levels (or LL decompositions) in the tree.
     *
     * @param 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.
     *
     * @param 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 WaveletTransform
     * */
    public Subband(int w, int h, int ulcx, int ulcy, int lvls,
                   WaveletFilter hfilters[], WaveletFilter vfilters[]) {
        int i,hi,vi;
        Subband cur; // The current subband

        // Initialize top-level node
        this.w = w;
        this.h = h;
        this.ulcx = ulcx;
        this.ulcy = ulcy;
        this.resLvl = lvls;
        // First create dyadic decomposition.
        cur = this;
        for (i=0; i<lvls; i++) {
            hi = (cur.resLvl <= hfilters.length) ? cur.resLvl-1 : 
		hfilters.length-1;
            vi = (cur.resLvl <= vfilters.length) ? cur.resLvl-1 : 
		vfilters.length-1;
            cur = cur.split(hfilters[hi],vfilters[vi]);
        }
    }

    /**
     * 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.
     *
     * @return The next subband in the same resolution level, following the
     * subband index order, or null if already at last subband.
     * */
    public Subband nextSubband() {
        Subband sb;

        if (isNode) {
            throw new IllegalArgumentException();
        }
        
        switch (orientation) {
        case WT_ORIENT_LL:
            sb = getParent();
            if (sb == null || sb.resLvl != resLvl) {
                // Already at top-level or last subband in res. level
                return null;
            }
            else {
                return sb.getHL();
            }
        case WT_ORIENT_HL:
            return getParent().getLH();
        case WT_ORIENT_LH:
            return getParent().getHH();
        case WT_ORIENT_HH:
            // This is the complicated one
            sb = this;
            while (sb.orientation == WT_ORIENT_HH) {
                sb = sb.getParent();
            }
            switch (sb.orientation) {
            case WT_ORIENT_LL:
                sb = sb.getParent();
                if (sb == null || sb.resLvl != resLvl) {
                    // Already at top-level or last subband in res. level
                    return null;
                }
                else {
                    sb = sb.getHL();
                }
                break;
            case WT_ORIENT_HL:
                sb = sb.getParent().getLH();
                break;
            case WT_ORIENT_LH:
                sb = sb.getParent().getHH();
                break;
            default:
                throw new Error("You have found a bug in JJ2000");
            }
            while (sb.isNode) {
                sb = sb.getLL();
            }
            return sb;
        default:
            throw new Error("You have found a bug in JJ2000");
        }
    }

    /**
     * Returns the first leaf subband element in the next higher resolution
     * level.
     *
     * @return The first leaf element in the next higher resolution level, or
     * null if there is no higher resolution level.
     * */
    public Subband getNextResLevel() {
        Subband sb;

        if (level == 0) { // No higher res. level
            return null;
        }
        // Go up until we get to a different resolution level
        sb = this;
        do {
            sb = sb.getParent();
            if (sb == null) { // No higher resolution level
                return null;
            }
        } while (sb.resLvl == resLvl);
        // Now go down to HL, which is in next higher resolution level
        sb = sb.getHL();
        // Now go down LL until get to a leaf
        while (sb.isNode) {
            sb = sb.getLL();
        }
        return sb;
    }

    /**
     * Returns a subband element in the tree, given its resolution level and
     * subband index. This method searches through the tree.
     *
     * @param rl The resolution level.
     *
     * @param sbi The subband index, within the resolution level.
     * */
    public Subband getSubbandByIdx(int rl, int sbi) {
        Subband sb,sb2;
        int d,ci;
        // Find the root subband for the resolution level
        if (rl > resLvl || rl < 0) {
            throw new IllegalArgumentException();
        }
        sb = this;
        while (sb.resLvl > rl) {
            sb = sb.getLL();
        }
        // Find depth in this res. level
        d = 0;
        sb2 = sb;
        while (sb2.isNode) {
            d++;
            sb2 = sb2.getHL();
        }
        // Check sbi
        ci = 1<<(d<<1); // ci = 4^d;
        if ((sbi < (ci>>2) || sbi >= ci)) {
            // If ((sbi < 4^(d-1)) || sbi >= 4^d)
            throw new IllegalArgumentException();
        }
        // Search for the subband
        ci >>=2;
        while (sb.isNode) {
            switch (sbi / ci) {
            case 0:
                sb = sb.getLL();
                break;
            case 1:
                sb = sb.getHL();
                break;
            case 2:
                sb = sb.getLH();
                break;
            case 3:
                sb = sb.getHH();
                break;
            default:
                throw new IllegalArgumentException();
            }
            sbi %= ci;
            ci >>= 2;
        }
        // Return subband
        return sb;
    }

    /**
     * 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.
     *
     * @param x horizontal coordinate of the specified point.
     *
     * @param y horizontal coordinate of the specified point.
     * */
    public Subband getSubband(int x, int y) {
        Subband cur,hhs;

        // Check that we are inside this subband
        if (x < ulx || y < uly || x >= ulx+w || y >= uly+h) {
            throw new IllegalArgumentException();
        }

        cur = this;
        while (cur.isNode) {
            hhs = cur.getHH();
            // While we are still at a node -> continue
            if (x < hhs.ulx) {
                // Is the result of horizontal low-pass
                if (y < hhs.uly) {
                    // Vertical low-pass
                    cur = cur.getLL();
                }
                else {
                    // Vertical high-pass
                    cur = cur.getLH();
                }
            }
            else {
                // Is the result of horizontal high-pass
                if (y < hhs.uly) {
                    // Vertical low-pass
                    cur = cur.getHL();
                }
                else {
                    // Vertical high-pass
                    cur = cur.getHH();
                }
            }                
        }

        return cur;
    }

    /**
     * Returns subband informations in a string.
     *
     * @return Subband informations
     * */
    public String toString() {
    
        String string =
            "w=" + w + ", h=" + h + ", ulx=" + ulx + ", uly=" + uly +
            ", ulcx= "+ulcx+", ulcy="+ulcy+", idx=" + sbandIdx +
            "\norient=" + orientation + ", node=" + isNode +
            ", level=" + level + ", resLvl=" + resLvl+ ", nomCBlkW=" +
            nomCBlkW + ", nomCBlkH=" + nomCBlkH;

        return string;
    }

    /** 
     * This function returns the horizontal wavelet filter relevant to this
     * subband
     *
     * @return The horizontal wavelet filter
     * */
    public abstract WaveletFilter getHorWFilter();

    /** 
     * This function returns the vertical wavelet filter relevant to this
     * subband
     *
     * @return The vertical wavelet filter
     * */
    public abstract WaveletFilter getVerWFilter();

    
}