ht2ft

Name

ht2ft - 2d hartley to fourier conversion

Syntax

ht2ft [-t <title>] <inimage> <outimage>

Description

ht2ft transforms a (single precision) real Hartley transform to a (single precision) complex Fourier transform. Note that the Hartley transform is faster than Fourier. If you need Fourier it may be faster to compute the Hartley transform and then convert to Fourier by means of ht2ft.

The Fourier transform is given by the Hartley transform as follows:

 F(u,v) = Re{F(u,v)} + j Im{F(u,v)}
        = H_e(u,v) - j H_o(u,v)
        = (H(u,v) + H(-u,-v))/2 - j (H(u,v) - H(-u,-v))/2

For images with horizontal and vertical even symmetry H_o(u,v) equals zero, so that

 F(u,v) = H_e(u,v) = H(u,v)

Restrictions

Input must be a single precision hartley transform

Return value

 0 => ok
 1 => bad number of arguments
 2 => couldn't read input file
 3 => couldn't write output file

Author

Tor Lønnestad, BLAB, Ifi, UiO

Examples

ht2ft monah.img monaf.img

Id

$Id: ht2ft.c,v 1.26 1997/05/27 14:48:35 svein Exp $