stdentropycoder.java

jpeg2000算法实现

    /**
     * Compresses the code-block in 'srcblk' and puts the results in 'ccb',
     * using the specified options and temporary storage.
     *
     * @param c The component for which to return the next code-block.
     *
     * @param ccb The object where the compressed data will be stored. If the
     * 'data' array of 'cbb' is not null it may be reused to return the
     * compressed data.
     *
     * @param srcblk The code-block data to code
     *
     * @param mq The MQ-coder to use
     *
     * @param bout The bit level output to use. Used only if 'OPT_BYPASS' is
     * turned on in the 'options' argument.
     *
     * @param out The byte buffer trough which the compressed data is stored.
     *
     * @param state The state information for the code-block
     *
     * @param distbuf The buffer where to store the distortion  at 
     * the end of each coding pass.
     *
     * @param ratebuf The buffer where to store the rate (i.e. coded lenth) at 
     * the end of each coding pass.
     *
     * @param istermbuf The buffer where to store the terminated flag for each 
     * coding pass.
     *
     * @param symbuf The buffer to hold symbols to send to the MQ coder
     *
     * @param ctxtbuf A buffer to hold the contexts to use in sending the
     * buffered symbols to the MQ coder.
     *
     * @param options The options to use when coding this code-block
     *
     * @param rev The reversible flag. Should be true if the source of this
     * code-block's data is reversible.
     *
     * @param lcType The type of length calculation to use with the MQ coder.
     *
     * @param tType The type of termination to use with the MQ coder.
     *
     * @see #getNextCodeBlock
     * */
    static private void compressCodeBlock(int c, CBlkRateDistStats ccb,
                                          CBlkWTData srcblk, MQCoder mq,
                                          BitToByteOutput bout,
                                          ByteOutputBuffer out,
                                          int state[],
                                          double distbuf[], int ratebuf[],
                                          boolean istermbuf[], int symbuf[],
                                          int ctxtbuf[], int options,
                                          boolean rev,
                                          int lcType, int tType) {
        // NOTE: This method should not access any non-final instance or
        // static variables, either directly or indirectly through other
        // methods in order to be sure that the method is thread safe.

        int zc_lut[];  // The ZC lookup table to use
        int skipbp;    // The number of non-significant bit-planes to skip
        int curbp;     // The current magnitude bit-plane (starts at 30)
        int fm[];      // The distortion estimation lookup table for MR
        int fs[];      // The distortion estimation lookup table for SC
        int lmb;       // The least significant magnitude bit
        int npass;     // The number of coding passes, for R-D statistics
        double msew;   // The distortion (MSE weight) for the current bit-plane
        double totdist;// The total cumulative distortion decrease
        int ltpidx;    // The index of the last pass which is terminated


        // Check error-resilient termination
        if ((options & OPT_ER_TERM) != 0 && tType != MQCoder.TERM_PRED_ER) {
            throw
                new IllegalArgumentException("Embedded error-resilient info "+
                                             "in MQ termination option "+
                                             "specified but incorrect MQ "+
                                             "termination "+
                                             "policy specified");
        }
        // Set MQ flags
        mq.setLenCalcType(lcType);
        mq.setTermType(tType);

        lmb = 30-srcblk.magbits+1;
        // If there are are more bit-planes to code than the implementation
        // bitdepth set lmb to 0
        lmb = (lmb < 0) ? 0:lmb;

        // Reset state
        ArrayUtil.intArraySet(state,0);

        // Find the most significant bit-plane
        skipbp = calcSkipMSBP(srcblk,lmb);

        // Initialize output code-block
        ccb.m = srcblk.m;
        ccb.n = srcblk.n;
        ccb.sb = srcblk.sb;
        ccb.nROIcoeff = srcblk.nROIcoeff;
        ccb.skipMSBP = skipbp;
        if(ccb.nROIcoeff!=0) {
            ccb.nROIcp = 3*(srcblk.nROIbp-skipbp-1)+1;
        } else {
            ccb.nROIcp = 0;
        }

        // Choose correct ZC lookup table for global orientation
        switch (srcblk.sb.gOrient) {
        case Subband.WT_ORIENT_HL:
            zc_lut = ZC_LUT_HL;
            break;
        case Subband.WT_ORIENT_LL:
        case Subband.WT_ORIENT_LH:
            zc_lut = ZC_LUT_LH;
            break;
        case Subband.WT_ORIENT_HH:
            zc_lut = ZC_LUT_HH;
            break;
        default:
            throw new Error("JJ2000 internal error");
        }
        
        // Loop on significant magnitude bit-planes doing the 3 passes
        curbp = 30-skipbp;
        fs = FS_LOSSY;
        fm = FM_LOSSY;
        msew = Math.pow(2,((curbp-lmb)<<1)-MSE_LKP_FRAC_BITS)*
            srcblk.sb.stepWMSE*srcblk.wmseScaling;
        totdist = 0f;
        npass = 0;
        ltpidx = -1;
        // First significant bit-plane has only the pass pass
        if (curbp >= lmb) {
            // Do we need the "lossless" 'fs' table ?
            if (rev && curbp == lmb) {
                fs = FM_LOSSLESS;
            }
            // We terminate if regular termination, last bit-plane, or next
            // bit-plane is "raw".
            istermbuf[npass] = (options & OPT_REG_TERM) != 0 || curbp == lmb ||
                ((options & OPT_BYPASS) != 0 &&
                 (31-NUM_NON_BYPASS_MS_BP-skipbp)>=curbp);
            totdist += cleanuppass(srcblk,mq,istermbuf[npass],curbp,state,
                                   fs,zc_lut,symbuf,ctxtbuf,ratebuf,
                                   npass,ltpidx,options)*msew;
            distbuf[npass] = totdist;
            if (istermbuf[npass]) ltpidx = npass;
            npass++;
            msew *= 0.25;
            curbp--;
        }
        // Other bit-planes have all passes
        while (curbp >= lmb) {
            // Do we need the "lossless" 'fs' and 'fm' tables ?
            if (rev && curbp == lmb) {
                fs = FS_LOSSLESS;
                fm = FM_LOSSLESS;
            }

            // Do the significance propagation pass
            // We terminate if regular termination only
            istermbuf[npass] = (options & OPT_REG_TERM) != 0;
            if ((options & OPT_BYPASS) == 0 ||
                (31-NUM_NON_BYPASS_MS_BP-skipbp<=curbp)) { // No bypass coding
                totdist += sigProgPass(srcblk,mq,istermbuf[npass],curbp,
                                       state,fs,zc_lut,
                                       symbuf,ctxtbuf,ratebuf,
                                       npass,ltpidx,options)*msew;
            }
            else { // Bypass ("raw") coding
                totdist += rawSigProgPass(srcblk,bout,istermbuf[npass],curbp,
                                          state,fs,ratebuf,npass,ltpidx,
                                          options)*msew;
            }
            distbuf[npass] = totdist;
            if (istermbuf[npass]) ltpidx = npass;
            npass++;
                
            // Do the magnitude refinement pass
            // We terminate if regular termination or bypass ("raw") coding
            istermbuf[npass] = (options & OPT_REG_TERM) != 0 ||
                ((options & OPT_BYPASS) != 0 &&
                 (31-NUM_NON_BYPASS_MS_BP-skipbp>curbp));
            if ((options & OPT_BYPASS) == 0 ||
                (31-NUM_NON_BYPASS_MS_BP-skipbp<=curbp)) { // No bypass coding
                totdist += magRefPass(srcblk,mq,istermbuf[npass],curbp,state,
                                      fm,symbuf,ctxtbuf,ratebuf,
                                      npass,ltpidx,options)*msew;
            }
            else { // Bypass ("raw") coding
                totdist += rawMagRefPass(srcblk,bout,istermbuf[npass],curbp,
                                         state,fm,ratebuf,
                                         npass,ltpidx,options)*msew;
            }
            distbuf[npass] = totdist;
            if (istermbuf[npass]) ltpidx = npass;
            npass++;

            // Do the clenup pass
            // We terminate if regular termination, last bit-plane, or next
            // bit-plane is "raw".
            istermbuf[npass] = (options & OPT_REG_TERM) != 0 || curbp == lmb ||
                ((options & OPT_BYPASS) != 0 &&
                 (31-NUM_NON_BYPASS_MS_BP-skipbp)>=curbp);
            totdist += cleanuppass(srcblk,mq,istermbuf[npass],curbp,state,
                                   fs,zc_lut,symbuf,ctxtbuf,ratebuf,
                                   npass,ltpidx,options)*msew;
            distbuf[npass] = totdist;
            if (istermbuf[npass]) ltpidx = npass;
            npass++;

            // Goto next bit-plane
            msew *= 0.25;
            curbp--;
        }

        // Copy compressed data and rate-distortion statistics to output
        ccb.data = new byte[out.size()];
        out.toByteArray(0,out.size(),ccb.data,0);
        checkEndOfPassFF(ccb.data,ratebuf,istermbuf,npass);
        ccb.selectConvexHull(ratebuf,distbuf,
                             (options&(OPT_BYPASS|OPT_REG_TERM))!=0?istermbuf:
                             null,npass,rev);

        // Reset MQ coder and bit output for next code-block
        mq.reset();
        if (bout != null) bout.reset();

        // Done
    }

    /**
     * Calculates the number of magnitude bit-planes that are to be skipped,
     * because they are non-significant. The algorithm looks for the largest
     * magnitude and calculates the most significant bit-plane of it.
     *
     * @param cblk The code-block of data to scan
     *
     * @param lmb The least significant magnitude bit in the data
     *
     * @return The number of magnitude bit-planes to skip (i.e. all zero most
     * significant bit-planes).
     **/
    static private int calcSkipMSBP(CBlkWTData cblk, int lmb) {
        int k,kmax,mask;
        int data[];
        int maxmag;
        int mag;
        int w,h;
        int msbp;
        int l;

        data = (int[]) cblk.getData();
        w = cblk.w;
        h = cblk.h;

        // First look for the maximum magnitude in the code-block
        maxmag = 0;
        // Consider only magnitude bits that are in non-fractional bit-planes.
        mask = 0x7FFFFFFF&(~((1<<lmb)-1));
        for (l=h-1, k=cblk.offset; l>=0; l--) {
            for (kmax = k+w; k<kmax; k++) {
                mag = data[k]&mask;
                if (mag > maxmag) maxmag = mag;
            }
            k += cblk.scanw-w;
        }
        // Now calculate the number of all zero most significant bit-planes for 
        // the maximum magnitude.
        msbp = 30;
        do {
            if (((1<<msbp)&maxmag)!=0) break;
            msbp--;
        } while (msbp>=lmb);
        
        // Return the number of non-significant bit-planes to skip
        return 30-msbp;
    }

    /**
     * Performs the significance propagation pass on the specified data and
     * bit-plane. It codes all insignificant samples which have, at least, one
     * of its immediate eight neighbors already significant, using the ZC and
     * SC primitives as needed. It toggles the "visited" state bit to 1 for
     * all those samples.
     *
     * @param srcblk The code-block data to code
     *
     * @param mq The MQ-coder to use
     *
     * @param doterm If true it performs an MQ-coder termination after the end
     * of the pass
     *
     * @param bp The bit-plane to code
     *
     * @param state The state information for the code-block
     *
     * @param fs The distortion estimation lookup table for SC
     *
     * @param zc_lut The ZC lookup table to use in ZC.
     *
     * @param symbuf The buffer to hold symbols to send to the MQ coder
     *
     * @param ctxtbuf A buffer to hold the contexts to use in sending the
     * buffered symbols to the MQ coder.
     *
     * @param ratebuf The buffer where to store the rate (i.e. coded lenth) at 
     * the end of this coding pass.