dct3D: Calculate and threshold DCT for an 3D image

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

Calculate and threshold DCT for an 3D image

Description

This function calculates the (orthonormal) discrete cosine transformation for a 3D image and returns thresholded DCT coefficients using the C-library fftw3 (see http://www.fftw.org/).

Usage

dct3D(image, qThresh)

Arguments

image	A 3D image (a 3D array with real values).
qThresh	A numeric with value in [0,1], giving the quantile for thresholding the coefficients. See dctBasis3D for details.

Value

ind	An integer vector, containing the indices of non-thresholded (hence non-zero) coefficients.
val	A numeric vector, giving the values of the corresponding 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

dctBasis3D

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