| .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 |
