## ISIS 2

ISIS Application Documentation

# fft

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Apply a Fourier Transform on a cube

 Overview Parameters Example 1

## Description

This programs takes a single input cube, applies a Fourier Transform, and stores the result in two bands of an output cube containing the magnitude and phase angle data. If the original image has dimensions that are not powers of two, it is automatically padded with zeroes. These images can then be used in the ifft program to recover the original.

## History

 Jacob Danton 2005-11-28 Original version Brendan George 2006-09-28 Documentation fixes Steven Lambright 2008-05-12 Removed references to CubeInfo Steven Lambright 2008-10-16 Documentation fixes: Created images for the GUI screenshots, which were missing. Steven Lambright 2012-02-24 This program now takes advantage of multiple global processing threads.

## Parameter Groups

### Files

Name Description
FROM Input file to apply the transform to
MAGNITUDE Magnitude output cube
PHASE Phase output cube

### Handling Special Pixels

Name Description
REPLACEMENTReplacement value

### Files: FROM

#### Description

The input cube on which the Fourier transform is applied.

 Type cube input *.cub

### Files: MAGNITUDE

#### Description

The resultant cube containing the image magnitude data.

 Type cube output real *.cub

### Files: PHASE

#### Description

The resultant cube containing the image phase angle data..

 Type cube output real *.cub

### Handling Special Pixels: REPLACEMENT

#### Description

This option specifies what special pixels will be replaced with.

Type string
Default ZEROES
Option List:
Option Brief Description
ZEROESReplace with Zeroes Replaces all special pixels with zeroes.
MINMAXReplace with max and min Replaces HRS and HIS pixels with the maximum value of the cube and LRS and LIS pixels with the minimum.

### Example 1

fft example

#### Description

Example of the Fourier transform.

#### Command Line

fft from=peaks.cub magnitude=peaks_magnitude.cub phase=peaks_phase.cub
Compute the Fourier transform of peaks.cub and store the results in peaks_magnitude.cub and peaks_phase.cub

#### GUI Screenshot

 fft GUI Example GUI Screenshot of GUI with parameters filled in to perform the fft application

#### Input Image

 Input image Input image for fft Parameter Name: FROM This is the input image, peaks.cub.

#### Output Images

 Magnitude image Example magnitude output Parameter Name: MAGNITUDE This is the magnitude output of the transform of peaks.cub. Phase image Example phase output Parameter Name: PHASE This is the phase output of the transform of peaks.cub.