fftrans(1) fftrans(1)
**NAME**
fftrans - to compute forward or reverse fourier transform of images
**SYNOPSIS**
fftrans [options] [input filename] [output filename]
**DESCRIPTION**
This program will do 2- or 3-dimensional FFT's in either direction. The
real-space origin is at (1,1) and the origin of reciprocal space is at
(1,NY/2+1) for 2-D FFT's. The FT of an image NX,NY is NX/2+1,NY com-
plex values. For 3-D FFT's, the origin is at (1,NY/2+1,NZ/2+1)
For distributed IMOD packages, transforms are done with FFTW and have
no restrictions on image dimensions. For a package not built with FFTW,
transforms are done using Lynn ten Eyck's subroutines. These allow
arbitrary-sized images with dimensions that are even and have a LARGEST
PRIME factor of 19.
3-D images are treated as stacks of images that are transformed inde-
pendently in 2-D, unless the -3dfft option is given.
If no command line arguments are given the program will request the
input and output file names interactively. Otherwise, the program uses
the PIP package for input (see pip). The following options can be
specified either as command line arguments (with the -) or one per line
in a command file (without the -). Options can be abbreviated to
unique letters; the currently valid abbreviations for short names are
shown in parentheses.
**-input** **(-i)** OR **-InputFile** *File* *name*
Input file with image or Fourier transform
**-output** **(-o)** OR **-OutputFile** *File* *name*
Output file for Fourier transform or inverse transform
**-3dfft** Take 3D instead of 2D FFT
**-mode** **(-m)** OR **-Mode** *Integer*
Mode of output file for inverse transform: 0 for bytes, 1 for
integers (default is 2 for reals)
**-quiet** **(-q)** OR **-Quiet**
Suppress header and min/max/mean outputs
**-help** **(-h)** OR **-usage**
Print help output.
**-StandardInput**
Read parameter entries from standard input.
**HISTORY**
Originally written by David Agard for VAX. David Mastronarde modified
to do in "memory" rather than use giantfft as long as the image will
actually fit into the dimensioned array. Also, changed to properly
package arrays in memory and use iwrsec to write sections.
10/24/04: Converted to PIP input and added 3D FFT, mode, quiet options.
7/15/13: Switched to dynamic array allocation; changes for FFTW
**BUGS**
Email bug reports to mast at colorado dot edu.
IMOD 4.9.3 fftrans(1)