Manual: pamaddnoise

Pamaddnoise User Manual(1)			   General Commands Manual			  Pamaddnoise User Manual(1)

NAME
       pamaddnoise - add noise to a Netpbm image

SYNOPSIS
       pamaddnoise { [-type gaussian]

       [-sigma1 value]

       [-sigma2 value] | -type	multiplicative_gaussian

       [-mgsigma value] | -type impulse

       [-tolerance ratio] | -type  laplacian

       [-lsigma value] | -type	poisson

       [-lambda value] } [-seed int]

       [netpbmfile]

DESCRIPTION
       This program is part of Netpbm(1).

       pamaddnoise adds the specified noise type to a Netpbm image.  pamaddnoise treats a PPM image as 3 independent planes,
       not as a plane of colors in a color space.

OPTIONS
       In addition to the options common to all programs based on libnetpbm (most notably -quiet, see  Common Options ), pa‐
       maddnoise recognizes the following command line options:

       -type noise_type
	      Select type of noise by name.  The following noise types are available: gaussian, multiplicative_gaussian, im‐
	      pulse,  laplacian, poisson.  Only enough letters to be unique are required for the noise type option.  The de‐
	      fault noise type is gaussian.

       gaussian

	      To each sample value is added the value of a two Gaussian random variables.
		  The variance of one is independent of the sample value, while the variance
		  of the other is proportional to the sample value.  You control these
		  variances with options -sigma1 and -sigma2 (and can eliminate
		  either by setting the variance to 0).	 The mean of the Gaussian
		  distributions is 0.

       multiplicative_gaussian

       impulse

	      This is 'salt and pepper' noise.	Samples are changed randomly
		  to zero or full brightness or left alone.  This is also know as salt and
		  pepper noise, as in a grayscale picture, it adds white pixels and black
		  pixels, which look like salt and pepper, respectively.  Control this with
		  options -tolerance and -salt.

       laplacian

       poisson

       -lambda value
	      This is valid only with -type=poisson.  It is the expected value of the  Poisson	distribution  for  a  sample
	      value  of	 maximum  intensity.  The expected value for other intensities is proportional; e.g. for half inten‐
	      sity, it is half this value.

	      The default value is 12.

       -lsigma value
	      This is meaningful only for laplacian noise.

	      The default value is 10.0.

       -mgsigma value
	      This is valid only for multiplicative gaussian noise.

	      The default value is 0.5.

       -seed int
	      This is the random number generator seed value.  Use this to get
		repeatable results.

       -sigma1 value
	      This is valid only for gaussian noise.  It is the standard deviation
		of the Gaussian random variable that is multiplied by the square root of
		each sample value and added to that sample value.

		  The default value is 4.0.

       -sigma2 value
	      This is valid only for gaussian noise.
		It is the standard deviation of the Gaussian random variable that is
		added directly to each sample value.

	      The default value is 20.0.

       -tolerance fraction
	      This is valid only for impulse noise.
		fraction is the fraction of samples that are changed
		in the output.	Whether each is changed to salt or pepper is controlled by
		-salt.

	      The default value is 0.10.

       -salt=fraction

	      This is valid only for impulse noise.  fraction is the
		  fraction of the pixels that are changed that are changed to salt (maxval);
		  the rest are changed to pepper (0).

	      The default is 0.5 (half salt, half pepper).

	      This option was new in Netpbm 11.04 (September 2023).  Before that, the
		noise is always half salt and half pepper.

REFERENCES
       •      "Adaptive Image Restoration in Signal-Dependent Noise" by R. Kasturi Institute for Electronic  Science,  Texas
	      Tech University, 1982

       •      "Digital Image Processing Algorithms" by Ioannis Pitas, Prentice Hall, 1993 ISBN 0-13-145814-0

SEE ALSO
       pgmnoise(1), pgmmedian(1), pnm(1), pam(1),

HISTORY
       pamaddnoise  was	 added	to Netpbm in Version 10.29 (August 2005).  It had been distributed by Mike Burns via his own
       web site before that (and continued to be so).

       Burns' version, and the one in Netpbm 10.29, was called pnmaddnoise and worked only on PNM images.  In Netpbm  10.30,
       it was converted to handle PAM images and renamed to pamaddnoise.

AUTHOR
       Copyright (C) 1995 by Mike Burns 

DOCUMENT SOURCE
       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at

	      http://netpbm.sourceforge.net/doc/pamaddnoise.html

netpbm documentation				       21 August 2023				  Pamaddnoise User Manual(1)