Digital Image Processing, Gonzales, R.C., Wintz, P., Addison Wesley, Second Edition, 1987, pp 100--109.
The Fourier Transform and Its Applications, Bracewell, R.N., McGraw-Hill, Second Edition, 1978.
Port: Img In
Spatial domain image.
Port: Img Out
Frequency domain image.
The packed format for a column places the real part of the DC component at the beginning of a vector, omits the zero imaginary part, then lists the complex frequencies up to the Nyquist frequency, then places the real part of the Nyquist frequency, omitting the zero imaginary part. The columns are arrange the same way, with a DC column followed by real-imaginary pairs of columns out to the Nyquist frequency, which has only a single column. The Nyquist row (column) is omitted in the case of an odd number of columns (rows).
For an even number of columns (nc) and even number of rows (nr), the packed format is (R=real, I=imag):
DC Nyquist R R I R I ... R I R R R I R I ... R I R I R I R I ... R I I R R I R I ... R I R I R I R I ... R I I ................... R R I R I ... R I R I R I R I ... R I I R R I R I ... R I R Nyquist