| Description | In Fourier domain filtering, the phase component after FFT is usually discarted. In the ITK (I)FFT filters only absolute images is produced. These images in MRI reflect spatial representation of proton densities, weighted by relaxation processes and pulse sequence setting. In the majority cases only absolute images are viewed by a radiologist.
However, recent image postprocessing techniques utilize also the phase information. Among the others, correction of geometric artifacts in EPI images (B0 field mapping), parallel imaging reconstruction algorithms (GRAPPA, SENSE), correction of partial volume effect in arterial input function in perfusion MRI, susceptibility weighted imaging, velocity measurements, and so on, utilize phase images after FFT.
Therefore, itkVnlFFTComplexConjugateToRealImageFilter should have an option to return: absolute, phase, real, imaginary images.
It is also suggested to rename the filter name. The current name gives an impression that the output of the filter is a real component (of a complex pair) image, while it in fact returns the absolute value. |