qccmatrixdct.3

来自「spiht for linux this is used to decod an」· 3 代码 · 共 82 行

.TH QCCMATRIXDCT 3 "QCCPACK" ""
.SH NAME
QccMatrixDCT,
QccMatrixInverseDCT
\- two-dimensional discrete cosine transform (DCT) and inverse transform 
of a matrix
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "int QccMatrixDCT(const QccMatrix " input_block ", QccMatrix " output_block ", int " num_rows ", int " num_cols );
.br
.BI "int QccMatrixInverseDCT(const QccMatrix " input_block ", QccMatrix " output_block ", int " num_rows ", int " num_cols );
.SH DESCRIPTION
.B QccMatrixDCT()
calculates the two-dimensional discrete cosine transform (2D DCT) of
.IR input_block ,
returning the result in
.IR output_block .
.LP
.B QccMatrixDCT()
calculates the 2D DCT of
.IR input_block
by first taking a one-dimensional DCT along each
row of the matrix followed by 
the one-dimensional DCT along each column.
.BR QccVectorDCT (3)
is used to calculate the one-dimensional DCT in each case.
.LP
.B QccMatrixInverseDCT()
calculates the two-dimensional inverse DCT of
.IR input_block ,
returning the result in
.IR output_block .
.SH "RETURN VALUE"
Both
.B QccMatrixDCT()
and
.B QccMatrixInverseDCT()
return 0 on success, 1 on error.
.SH IMPLEMENTATION
These routines implement the type-II DCT applied separably;
the implementation is slow, and s based on calls to
.BR QccVectorDCT (3)
and
.BR QccVectorInverseDCT (3)
which, in turn, call directly to
.BR cos (3).
Most applications should probably use
.BR QccFastDCTForwardTransform2D (3)
and
.BR QccFastDCTInverseTransform2D (3)
which are based on a faster FFT-based implementation, but
rely on the GNU Scientific Library (GSL) for the FFT.
.BR QccMatrixDCT()
and
.BR QccMatrixInverseDCT()
are provided for use when GSL is not available.
.SH "SEE ALSO"
.BR QccVectorDCT (3),
.BR QccFastDCTForwardTransform2D (3),
.BR QccMatrix (3),
.BR QccPack (3)

A. K. Jain,
.IR "Fundamentals of Digital Image Processing" .
Englewood Cliffs, NJ: Prentice Hall, 1989.
.SH AUTHOR
Copyright (C) 1997-2009  James E. Fowler
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