.TH QCCWAVSRENCODE 1 "QCCPACK" "".SH NAMEQccWAVsrEncode, QccWAVsrDecode \-encode/decode an image using the SR algorithm.SH SYNOPSIS.B #include "libQccPack.h".sp.BI "int QccWAVsrEncode(QccIMGImageComponent *" image ", QccBitBuffer *" buffer ", QccSQScalarQuantizer *" quantizer ", int " num_levels ", QccWAVWavelet *" wavelet ", QccWAVPerceptualWeights *" perceptual_weights );.sp.BI "int QccWAVsrDecodeHeader(QccBitBuffer *" buffer ", int *" num_levels ", int *" num_rows ", int *" num_cols ", QccSQScalarQuantizer *" quantizer ", double *" image_mean );.sp.BI "int QccWAVsrDecode(QccBitBuffer *" buffer ", QccIMGImageComponent *" image ", QccSQScalarQuantizer *" quantizer ", int " num_levels ", QccWAVWavelet *" wavelet ", QccWAVPerceptualWeights *" perceptual_weights ", double " image_mean );.SH DESCRIPTION.LP.B QccWAVsrEncode()encodes an image component,.IR image ,using the stack-run (SR) algorithm by Tsai .IR "et al" .The SR algorithm involves a 2D DWT followed by uniform scalar quantization of the wavelet coefficients.Runs of the zero index are identified and are run-length encoded.The SR algorithm then uses a 4-symbol alphabet to code the binary digitsof the runs and the quantizer indices of the nonzero coefficients(the "stacks").  The stream of symbols from this 4-symbol alphabetis then coded with arithmetic entropy coding..LP.I imageis the image component to be coded,.I bufferis the output bitstream following arithmetic coding (must be of.B QCCBITBUFFER_OUTPUTtype and opened via a prior call to.BR QccBitBufferStart (3)),.I quantizeris the scalar quantizer (see below),.I num_levelsgives the number of levels of dyadic wavelet decomposition to perform,.I waveletis the wavelet to use for decomposition,and.I perceptual_weightsis the optional perceptual weights to employ (use.B NULLfor no perceptual weighting)..LPThe rate-distortion performance of the SR algorithm is determined by thestepsize of the uniform scalar quantizer, .IR quantizer ..I quantizermay be of either.B QCCSQSCALARQUANTZIER_UNIFORMor.B QCCSQSCALARQUANTIZER_DEADZONEtype.  That is,.I quantizermay be either uniform or uniform with adead zone (see.BR squniform (1)for more details).Using a dead zone may allow longer runs of zeros and may increasecompression performance in some cases..LPNote:.BR QccWAVsrEncode()currently achieves rate-distortion performance slightly below that reportedby Tsai .IR "et al" .For instance, when coding the "Barbara" image at 0.5 bits/pixel, .B srencode achieves a PSNR about 0.5dB below the reported figure.The reasons for this performance gap are currently being investigated..LP.B QccWAVsrDecodeHeader()decodes the header information in the bitstream in the input.I buffer(which must be of.B QCCBITBUFFER_INPUTtype and opened via a prior call to.BR QccBitBufferStart (3)).The header information is returned in.I num_levels(number of levels of wavelet decomposition),.I num_rows(vertical size of image),.I num_cols(horizontal size of image),.I quantizer(scalar quantizer, including stepsize and any deadzone stored in header),and.I image_mean(the mean value of the original image)..LP.B QccWAVsrDecode()decodes the bitstream.IR buffer ,producing the reconstructed image component,.IR image .The bitstream must already have had its header read by a prior callto.B QccWAVsrDecodeHeader()(i.e., you call.B QccWAVsrDecodeHeader() first and then.BR QccWAVsrDecode() )..SH "SEE ALSO".BR srencode (1),.BR srdecode (1),.BR imgdwt (1),.BR squniform (1),.BR QccBitBuffer (3),.BR QccWAVPerceptualWeights (3),.BR QccWAVSubbandPyramid (3),.BR QccPackWAV (3),.BR QccPackIMG (3),.BR QccPack (3)M.-J. Tsai, J. D. Villasenor, and F. Chen,"Stack-Run Image Coding,".IR "IEEE Transactions on Circuits and Systems for Video Technology" ,vol. 6, no. 5, pp. 519-521, October 1996.M.-J. Tsai, J. D. Villasenor, and F. Chen,"Stack-Run Coding for Low Bit Rate Image Communication,".IR "Proceedings IEEE International Conference on Image Processing" ,pp. 681-684, September 1996..SH AUTHORCopyright (C) 1997-2005  James E. Fowler.\"  The programs herein are free software; you can redistribute them and/or.\"  modify them under the terms of the GNU General Public License.\"  as published by the Free Software Foundation; either version 2.\"  of the License, or (at your option) any later version..\"  .\"  These programs are distributed in the hope that they will be useful,.\"  but WITHOUT ANY WARRANTY; without even the implied warranty of.\"  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the.\"  GNU General Public License for more details..\"  .\"  You should have received a copy of the GNU General Public License.\"  along with these programs; if not, write to the Free Software.\"  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.