vspeckle(1)

PROGRAM
vspeckle - Reduce speckle noise from an image by using the Crimmins algorithm.

SYNTAX

vspeckle

-i  input image

-o  output image

[-n]
    Iterations

[-V]
    Gives the version for vspeckle

[-U]
    Gives the usage for vspeckle

[-P]
    Prompts for command line options

[-A [file1]]
    Creates the answer file called vspeckle.ans or file1

[-a [file1]]
    Uses vspeckle.ans or file1 as the answer file

DESCRIPTION
vspeckle reduces the "speckle" noise from an image. It uses the "eight hull algorithm" developed by T. R. Crimmins to perform this reduction.

The function takes one argument: n which determines how many times the image is to be sent through the speckle reducing filter. This filter uses the complementary hulling technique to reduce the speckle index of an image.

Each pixel in the image is compared with all eight of its surrounding pixels. The pixels above and below the pixel are the N-S pair, the pixels on either side are the E-W pair, those on the diagonals are the NW-SE and NE-SW pair. The image and a pair of pixels are sent to the symmetric hull function which in turn sends the image to the positive hull function and to the negative hull function. The positive and negative hull functions are called twice; the first time the neighboring pair of pixels is sent and the second time the complement of the pixels is sent. The positive hull function replaces each "middle pixel" with the result of a several comparisons. These comparison are a combination of maximums and minimums. The final comparison is a maximum for the postive hull algorithm. The image is then sent to the negative hull function where the middle pixel is replaced with the result of more comparisons. The final comparison for the negative hull algorithm is a minimum. The result of all these replacements has the effect of reducing the undesired speckle noise while preserving the edges of the original image. The Geometric filter for speckle reduction is described in Applied Optics, Vol. 24, No. 10, 15 May 1985, Geometric fileter for speckle reduction, by Thomas R Crimmins.

REQUIRED ARGUMENTS

-i  type: infile
    desc: input image

-o  type: outfile
    desc: output image

OPTIONAL ARGUMENTS

-n  type: integer
    desc: Iterations
    default: 1
    bounds: 1 < [-n] < 20

EXAMPLES
vspeckle -i image1 -o image2 -n 2

This command sends the image through the geometric filter twice. Most of the speckle noise is removed from image1 and the result is stored in image2.

SEE ALSO
intro(1), verror(3), vgparms(3), vutils(3), lvspeckle(3) lvspeckle(3)

RESTRICTIONS
vspeckle accepts only BYTE images. The number of iterations is limited to 20.

COPYRIGHT
Copyright 1991, University of New Mexico. All rights reserved.