im_addgnoise - add gaussian noise to an image
int im_addgnoise(in, out, sigma)
IMAGE *in, *out;
im_addgnoise() adds gaussian noise with mean 0 and standard deviation
sigma to the image held by the image descriptor in and writes the
result on the image descriptor out. The function works on any non-
complex input image. Input can have any no of bands. The noise is
generated by adding 12 random numbers.
The function returns 0 on success and -1 on error.
im_add(3), im_lintra(3), im_multiply(3).
N. Dessipris - 25/04/1991
14 May 1991