dct2D function

Calculate and threshold DCT for an image

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

dct2D(image, qThresh)

Arguments

• image: An image (a 2D matrix with real values).
• qThresh: A numeric with value in $[0,1]$, giving the quantile for thresholding the coefficients. See dctBasis2D for details.

Returns

• 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

dctBasis2D