idct2D: Calculate an inverse DCT for an image

In MFPCA: Multivariate Functional Principal Component Analysis for Data Observed on Different Dimensional Domains

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.

See Also

dctBasis2D

MFPCA documentation built on Sept. 15, 2022, 9:07 a.m.