64 lines
1.6 KiB
Groff
64 lines
1.6 KiB
Groff
.TH GAUSS_MASKS 3 "6 December 1991"
|
|
.SH NAME
|
|
im_gauss_dmask, im_gauss_imask \- create a gaussian DOUBLEMASK or INTMASK
|
|
.SH SYNOPSIS
|
|
.B #include <vips/vips.h>
|
|
|
|
.B DOUBLEMASK im_gauss_dmask( name, sigma, min_amplitude )
|
|
.br
|
|
char *name;
|
|
.br
|
|
double sigma, min_amplitude;
|
|
|
|
.B INTMASK im_gauss_imask( name, sigma, min_amplitude )
|
|
.br
|
|
char *name;
|
|
.br
|
|
double sigma, min_amplitude;
|
|
|
|
.B INTMASK im_gauss_imask_sep( name, sigma, min_amplitude )
|
|
.br
|
|
char *name;
|
|
.br
|
|
double sigma, min_amplitude;
|
|
|
|
.SH DESCRIPTION
|
|
Both functions create a circularly symmetric Gaussian mask of sigma. The size
|
|
of the mask is determined by the variable min_amplitude; if for instance the
|
|
value .1 is entered this means that the produced mask is clipped at values
|
|
less than 10 percent of the maximum amplitude.
|
|
The mask can be directly used with the vasari convolution
|
|
programs, the default offset set is 0.
|
|
|
|
The program uses the following equation:
|
|
|
|
H(r) = exp( -(r * r) / (2 * sigma * sigma) ).
|
|
|
|
The generated mask has odd size and its maximum value is normalised to
|
|
either 100 (gauss_imask) or to 1.0 (gauss_dmask).
|
|
|
|
.B im_gauss_dmask(3)
|
|
creates a DOUBLEMASK laplacian of Gaussian mask with maximum value normalised
|
|
to 1.0.
|
|
|
|
.B im_gauss_imask(3)
|
|
creates a INTMASK laplacian of Gaussian mask with maximum value normalised
|
|
to 100.
|
|
|
|
.B im_gauss_imask_sep(3)
|
|
returns the centre line of
|
|
.B im_gauss_imask(3).
|
|
It is convenient for use with
|
|
.B im_conv_sep(3)
|
|
for building fast gaussian blur or sharpen.
|
|
|
|
.SH RETURNED VALUE:
|
|
The functions return NULL on erorr.
|
|
.SH SEE ALSO
|
|
im_log_dmask(3), im_conv(3), im_conv_sep(3).
|
|
.SH COPYRIGHT
|
|
.br
|
|
N. Dessipris
|
|
.SH AUTHOR
|
|
N. Dessipris \- 06/12/1991
|