Boulder Laboratory for 3-Dimensional Electron Microscopy of Cells 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 complex values. For 3-D FFT's, the origin is at (1,NY/2+1,NZ/2+1) All 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 independently in 2-D, unless the -3dfft option is given. Large images (up to 5K x 5K) are transformed in memory. Very large images (up to 8192 x 8192) are transformed using the disk-based routine BIGFFT. In this case, only a single section can be transformed. 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 -): -input OR -InputFile File name Input file with image or Fourier transform -output OR -OutputFile File name Output file for Fourier transform or inverse transform -3dfft Take 3D instead of 2D FFT -mode OR -Mode Integer Mode of output file for inverse transform: 0 for bytes, 1 for integers (default is 2 for reals) -quiet OR -Quiet Suppress header and min/max/mean outputs -help 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.