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