FourierPhaseImg

DESCRIPTION

Extracts the phase values of a frequency domain image into a smaller array. Since each phase is a real number derived from complex input, the output array has approximately half the amount of useful data of the input. The output compresses all phases to produce an array that has (NC/2 + 1) columns for an input of NC columns. Thus the output array is not compatible for use with the InverseFFTImg module. Instead, the output should be combined using FourierMergeImg with a magnitude array output by FourierMagnitudeImg to give a frequency domain image that can be transformed back into the time domain. The input must be a frequency domain image in the packed format produced by the ForwardFFTImg module (see format description in ForwardFFTImg documentation). The Fourier transformation and the cross correlation are discussed in:

Digital Image Processing, Gonzales, R.C., Wintz, P., Addison Wesley, Second Edition, 1987, pp 61--137.

INPUTS

Port: Img In
Type: Lattice
Constraints: 1..3-D
Source frequency domain image.

WIDGETS

OUTPUTS

Port: Img Out
Type: Lattice
Constraints: 1..3-D
Phase values (compressed).

KNOWN PROBLEMS

SEE ALSO

ForwardFFTImg, InverseFFTImg, FourierMergeImg, FourierMagnitudeImg.
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© The Numerical Algorithms Group Ltd, Oxford UK. 2000