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.



BL3DEMC                              4.7.3                          fftrans(1)