FourierMagnitudeImg

DESCRIPTION

Extracts the magnitude values of a frequency domain image into a smaller array. Each magnitude is computed as the norm of a complex number, sqrt ( R2 + I2 ). The output suppresses all zero imaginary values 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 phase array output by FourierPhaseImg 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 is 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
Real magnitude image (compressed).

KNOWN PROBLEMS

SEE ALSO

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