RETRO (vipl) functions


LIBRARY ROUTINE

lvfht - Perorm fast hadamard transform on the input image

LIBRARY CALL

int lvfht (
	xvimage *img,
	int inv_flag)

INPUT

OUTPUT

RETURN VALUE

TRUE (1) on success, FALSE (0) on failure

DESCRIPTION

This command performs a fast hadamard transform on the image.

If your input image had dimensions 4 row by 4 columns, and the image had a constant value as shown below

input image = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }

The output would be this

output image = { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }

Because the input image was simply the first of the Hadamard basis functions with magnitude = 1.

The Following references were used in creating this program :

1. "Digital Image Processing, Second Edition", Rafael C. Gonzalex, Paul Wintz, Addison-Wesley Publishing Company, Reading Massachusetts, 1987

2. "The C User's Journal", July 1989, "The Fast Walsh Transform", p101, Ian AshDown

ADDITIONAL INFORMATION

none

EXAMPLES

none

SIDE EFFECTS

none

RESTRICTIONS

lvfht only works on images of type VFF_TYP_FLOAT. The dimensions of the input image must both be non-zero powers of two. Images with maps or explicit location data are not allowed.

MODIFICATION

none

FILES

$RETRO/objects/library/vipl/src/lvfht.c

SEE ALSO

vipl(3)

COPYRIGHT

Copyright (C) 1993 - 1997, Khoral Research, Inc. ("KRI") All rights reserved.