ISMOOTH-2-D smooth of image using 9-point smoothing algorithm

Description:

ISMOOTH, which smooths a 2-D image using a nine-point 2-D smoothing algorithm. This is a 2-D extension of the 3-point spectrum smoothing algorithm which replaces each pixel with 1/2 its own value plus 1/4 of the value of each of its two neighbours. The routine used here replaces each pixel with a fraction of its own value plus a fraction of the value of its eight nearest neighbours. The fraction from a 'corner' neighbour is 1.414 times less than from a 'side' neighbour. Repeating the process increases the amount of smothing applied, and the operation is close in effect to a gaussian convolution.

Parameters:

IMAGE

Name of image to be smoothed.

FRACTION

Fraction of pixel data for redistribution.

REPEAT

Number of times to repeat basic smoothing.

OUTPUT

Name of resulting image.

See also:

FIGARO: ICONV3, IXSMOOTH, MEDFILT.
KAPPA: CONVOLVE, FFCLEAN, GAUSMOOTH, MEDIAN.

Source comments:

 I S M O O T H

 This routine is the main body of ISMOOTH, which smooths
 a 2-D image using a nine-point 2-D smoothing algorithm.  This
 is a 2-D extension of the 3-point spectrum smoothing algorithm
 which replaces each pixel with 1/2 its own value plus 1/4 of
 the value of each of its two neighbours.  The routine used here
 (see GEN_ASMOTH for details) replaces each pixel with a fraction
 of its own value plus a fraction of the value of its eight nearest
 neighbours.  The fraction from a 'corner' neighbour is 1.414 times
 less than from a 'side' neighbour.  Repeating the process increases
 the amount of smothing applied, and the operation is close in
 effect to a gaussian convolution.

 Command parameters -

 IMAGE    The name of the structure containing the image.

 FRACTION (Numeric) The fraction of each pixel's value to be
          distributed to its neighbours.  The higher this
          value the greater the smoothing effect.

 REPEAT   (Numeric) The number of times the operation is to
          be repeated.  The higher this value, the greater
          the smoothing effect.

 OUTPUT   The name of the result of the operation.  This can
          be the same as for IMAGE.  If not, a new structure
          is created, with everything but the data a direct
          copy of the input.

                                  KS / CIT 21st June 1983