idct2D {MFPCA} | R Documentation |
Calculate an inverse DCT for an image
Description
This function calculates an inverse (orthonormal) discrete cosine
transformation for given coefficients in two dimensions using the
C-library fftw3
(see http://www.fftw.org/). As many
coefficients are expected to be zero, the values are given in
compressed format (indices and values only of non-zero coefficients).
Usage
idct2D(scores, ind, dim)
Arguments
scores |
A numeric vector, containing the non-zero coefficients. |
ind |
An integer vector, containing the indices of the non-zero coefficients. |
dim |
A numeric vector of length 2, giving the resulting image dimensions. |
Value
A matrix of dimensions dim
, which is a linear
combination of cosine tensor basis functions with the given
coefficients.
Warning
If the C-library fftw3
is not available when
the package MFPCA
is installed, this function is disabled an
will throw an error. For full functionality install the C-library
fftw3
from http://www.fftw.org/ and reinstall
MFPCA
. This function has not been tested with
ATLAS/MKL/OpenBLAS.