idct2D function

Calculate an inverse DCT for an image

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).

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.

Returns

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