qccwavliftingscheme.3

QccPack implementation in C

.TH QCCWAVLIFTINGSCHEME 3 "QCCPACK" ""
.SH NAME
QccWAVLiftingScheme \- 
data structure 
.B QccWAVLiftingScheme
and corresponding
.B LFT
file format for wavelet-based analysis/synthesis using a
lifting implementation
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "int QccWAVLiftingSchemeInitialize(QccWAVLiftingScheme *" lifting_scheme );
.br
.BI "int QccWAVLiftingSchemePrint(const QccWAVLiftingScheme *" lifting_scheme );
.br
.BI "int QccWAVLiftingSchemeBiorthogonal(const QccWAVLiftingScheme *" lifting_scheme );
.SH DESCRIPTION
QccPack provides data structure
.B QccWAVLiftingScheme
for representing a lifting scheme for a two-band wavelet-based
analysis and synthesis using lifting (as opposed to filtering; see
.BR QccWAVFilterBank (3) ).
This lifting-scheme structure can be read from and written to 
.BR LFT -format
files, or a
.B QccWAVLiftingScheme
structure can be used without file input or output.
.LP
The only component of the lifting-scheme structure is an integer
code indicating which lifting scheme to employ.
This is due to the fact that the lifting implementations of
wavelet analysis and synthesis are "hard-coded" into the QccPack library
for purposes of execution speed and ease of implementation
(this is opposed to the situation for filter-based analysis and synthesis
which employ generic filter routines and read coefficients from files).
As a consequence, only a limited number (see below) of wavelets
are current supported, and this list cannot be extended by the user
(without modifying the QccPack source code, or course).
.SH "DATA STRUCTURE"
The
.B QccWAVLiftingScheme
data structure is defined as:
.RS
.nf

typedef struct
{
  QccString filename;
  QccString magic_num;
  int major_version;
  int minor_version;
  int scheme;
} QccWAVLiftingScheme;
.fi
.RE
.LP
The fields of
.B QccWAVLiftingScheme
are as follows:
.TP
.I filename
The name of the file.
.TP
.IR magic_num ", " major_version ", " minor_version
The magic number and version of the file.
.TP
.IR scheme
The integer code denoting which lifting scheme to employ.
The current possibilities are limited to
.BR QCCWAVLIFTINGSCHEME_LWT
(Lazy Wavelet transform),
.BR QCCWAVLIFTINGSCHEME_Daubechies4
(Daubechies length-4 orthonormal wavelet),
.BR QCCWAVLIFTINGSCHEME_CohenDaubechiesFeauveau9_7
(Cohen-Daubechies-Feauveau length 9-7 biorothogonal wavelet),
and
.BR QCCWAVLIFTINGSCHEME_CohenDaubechiesFeauveau5_3
(Cohen-Daubechies-Feauveau length 5-3 biorthogonal wavelet,
which is also known as "linear lifting").
.SH "FILE FORMAT"
For reading and writing structures
of type
.BR QccWAVLiftingScheme ,
QccPack provides the
.B LFT
file format.
This file format starts with an ASCII header followed by
binary data.
The ASCII header consists of magic-number/revision
information
followed by any amount of white space
(space, `\\t' (tab), `\\n' (newline), `\\r' (return)) and/or
comments lines (lines starting with `#').  
The ASCII integer corresponding to
.I scheme is given following the header.
.LP
The
.B LFT
file format consists of the following information:
.RS
.sp
.BI LFT X.X
.br
.I "<white space>"
.br
.I scheme
.br
.sp
.RE
where
.B LFT
is the magic number,
.I X.X
is the version number,
.I "<white space>"
is white space and/or 
comment lines, 
and
.I scheme
is the lifting scheme.
.SH "ROUTINES"
.B QccWAVLiftingSchemeInitialize()
should be called before any use of a
.B QccWAVLiftingScheme
structure.
.B QccWAVLiftingSchemeInitialize()
initializes the fields of
.I lifting_scheme
to the following values:
.RS

.IR filename :
.B NULL
string
.br
.IR magic_num :
.B QCCLIFTINGSCHEME_MAGICNUM
.br
.IR major_version ", " minor_version :
initialized to output of 
.BR QccGetQccPackVersion (3)
.br
.IR scheme :
-1 (undefined)
.RE
.LP
.B QccWAVLiftingSchemePrint()
prints the contents of
.I lifting_scheme
to stdout.
.LP
.BR QccWAVLiftingSchemeBiorthogonal()
returns 1 if
.I lifting_scheme 
is biorthogonal, 0 otherwise.
.SH "FILES"
QccPack comes with the following
.BR LFT-
format files for specifying certain lifting wavelets.
The
.BR LFT
files and their corresponding wavelets are
.RS

LWT.lft - Lazy Wavelet transform
.br
CohenDaubechiesFeauveau.5-3.lft - length 9/5 biorthogonal wavelet
.br
CohenDaubechiesFeauveau.9-7.lft - length 9/7 biorthogonal wavelet
.br
Daubechies.4.lft - length 4 orthogonal wavelet
.RE
.SH "RETURN VALUE"
These routines return 0 on success, and 1 on failure.
.SH "SEE ALSO"
.BR QccPackWAV (3),
.BR QccPack (3)
.SH AUTHOR
Copyright (C) 1997-2005  James E. Fowler
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