1GAUSS_MASKS(3)             Library Functions Manual             GAUSS_MASKS(3)
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NAME

6       im_gauss_dmask,  im_gauss_imask  - create a gaussian DOUBLEMASK or INT‐
7       MASK
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SYNOPSIS

10       #include <vips/vips.h>
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12       DOUBLEMASK im_gauss_dmask( name, sigma, min_amplitude )
13       char *name;
14       double sigma, min_amplitude;
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16       INTMASK im_gauss_imask( name, sigma, min_amplitude )
17       char *name;
18       double sigma, min_amplitude;
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DESCRIPTION

21       Both functions create a circularly symmetric Gaussian  mask  of  sigma.
22       The  size  of  the mask is determined by the variable min_amplitude; if
23       for instance the value .1 is entered this means that the produced  mask
24       is  clipped  at  values  less than 10 percent of the maximum amplitude.
25       The mask can be directly used with the vasari convolution programs, the
26       default offset set is 0.
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28       The program uses the following equation:
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30          H(r) = exp( -(r * r) / (2 * sigma * sigma) ).
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32       The  generated mask has odd size and its maximum value is normalised to
33       either 100 (gauss_imask) or to 1.0 (gauss_dmask).
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35       im_gauss_dmask() creates a DOUBLEMASK laplacian of Gaussian  mask  with
36       maximum value normalised to 1.0.
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38       im_gauss_imask() creates a INTMASK laplacian of Gaussian mask with max‐
39       imum value normalised to 100.
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RETURNED VALUE:

42       The functions return NULL on erorr.
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SEE ALSO

45       im_log_dmask(3), im_conv(3)
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48       N. Dessipris
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AUTHOR

51       N. Dessipris - 06/12/1991
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55                                6 December 1991                 GAUSS_MASKS(3)
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