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Pamfunc User Manual(0)							   Pamfunc User Manual(0)

NAME
       pamfunc - Apply a simple monadic arithmetic function to a Netpbm image

SYNOPSIS
       pamfunc	{ -multiplier=realnum | -divisor=realnum | -adder=integer | -subtractor=integer |
       -min=wholenum  |  -max=wholenum	-andmask=hexmask  -ormask=hexmask  -xormask=hexmask  -not
       -shiftleft=count -shiftright=count } [filespec]

       All  options  can be abbreviated to their shortest unique prefix.  You may use two hyphens
       instead of one.	You may separate an option name and its value with white space instead of
       an equals sign.

DESCRIPTION
       This program is part of Netpbm(1)

       pamfunc reads a Netpbm image as input and produces a Netpbm image as output, with the same
       format, maxval, and dimensions as the input.  pamfunc applies a simple  transfer  function
       to  each  sample  in  the  input  to generate the corresponding sample in the output.  The
       options determine what function.

       pamarith is the same thing for binary functions --  it  takes  two  images  as  input  and
       applies	a  specified  simple arithmetic function (e.g. addition) on pairs of samples from
       the two to produce the single output image.

OPTIONS
       -multiplier=realnum

	      This option makes the transfer function that of multiplying by
		   realnum.  realnum must be nonnegative.  If the result
		   is greater than the image maxval, it is clipped to the maxval.

	      Where the input is a PGM or PPM image, this has the effect of
		   dimming or brightening it.  For a different kind of brightening,
		   see ppmbrighten(1)
	       and ppmflash(1)

	      Also, see ppmdim(1) , which does the
		   same thing as pamfunc -multiplier on a PPM image with a
		   multiplier between 0 and 1,
		   except it uses integer arithmetic, so it may be faster.

	      And ppmfade(1)
	       can generate a whole
		   sequence of images of brightness declining to black or increasing to
		   white, if that's what you want.

       -divisor=realnum

	      This option makes the transfer function that of dividing by
		   realnum.  realnum must be nonnegative.  If the result
		   is greater than the image maxval, it is clipped to the maxval.

	      This is the same function as you would get with -multiplier,
		   specifying the multiplicative inverse of realnum.

       -adder=integer

	      This option makes the transfer function that of adding
		   wholenum.  If the result is greater than the image maxval,
		   it is clipped to the maxval.  If it is less than zero, it is
		   clipped to zero.

	      Note that in mathematics, this entity is called an 'addend,'
		   and an 'adder' is a snake.  We use 'adder' because
		   it makes more sense.

       -subtractor=integer

	      This option makes the transfer function that of subtracting
		   wholenum.  If the result is greater than the image maxval,
		   it is clipped to the maxval.  If it is less than zero, it is
		   clipped to zero.

	      Note that in mathematics, this entity is called a
		   'subtrahend' rather than a 'subtractor.'  We
		   use 'subtractor' because it makes more sense.

	      This is the same function as you would get with -adder,
		   specifying the negative of integer.

       -min=wholenum

	      This option makes the transfer function that of taking the
		   maximum of the argument and wholenum.  I.e the minimum
		   value in the output will be wholenum.

		   If wholenum is greater than the maxval, though, every sample
		   in the output will be maxval.

       -max=wholenum

	      This option makes the transfer function that of taking the
		   minimum of the argument and wholenum.  I.e the maximum
		   value in the output will be wholenum.

		   If wholenum is greater than the maxval, the function is
		   idempotent -- the output is identical to the input.

       -andmask=hexmask

	      This option makes the transfer function that of bitwise anding
		   with hexmask.

	      hexmask is in hexadecimal.  Example: 0f

	      See section Maxval <#maxval>  for the special
		   meaning of maxval with respect to bit string operations such as
		   this.

	      This option was new in Netpbm 10.40 (September 2007).

       -ormask=hexmask

	      This option makes the transfer function that of bitwise
		   inclusive oring with hexmask.

	      This is analogous to -andmask.

	      This option was new in Netpbm 10.40 (September 2007).

       -xormask=hexmask

	      This option makes the transfer function that of bitwise
		   exclusive oring with hexmask.

	      This is analogous to -andmask.

	      This option was new in Netpbm 10.40 (September 2007).

       -not

	      This option makes the transfer function that of bitwise logical
		   inversion (e.g. sample value 0xAA becomes 0x55).

	      See section Maxval <#maxval>  for the special
		   meaning of maxval with respect to bit string operations such as
		   this.

	      pnminvert does the same thing for a bilevel visual image
		   which has maxval 1 or is of PBM type.

	      This option was new in Netpbm 10.40 (September 2007).

       -shiftleft=count

	      This option makes the transfer function that of bitwise shifting
		   left by count bits.

	      See section Maxval <#maxval>  for the special
		   meaning of maxval with respect to bit string operations such as
		   this.

	      This option was new in Netpbm 10.40 (September 2007).

       -shiftright=count

	      This option makes the transfer function that of bitwise shifting
		   right by count bits.

	      This is analogous to -shiftleft.

	      This option was new in Netpbm 10.40 (September 2007).

MAXVAL
       For the arithmetic functions, the maxval has no meaning.  The function applies to the sam-
       ple  value  as  an  integer.  (Note that this differs from the usual interpretation of PAM
       samples as being a fraction of a maxval, but does produce more intuitive result: 2 times 5
       is 10.

       But  with  the  bit string operations, the maxval has a special meaning.  The functions in
       question are: -andmask, -ormask, -xormask, -not, -shiftleft, and -shiftright.

       With these, each sample value the input image, and in the output image, represents  a  bit
       string,	not a number.  The maxval tells how wide the bit string is.  The maxval must be a
       full binary count (a power of two minus one, such as 0xff) and the number of ones in it is
       the width of the bit string.

       For  a  masking	function,  the mask value you specify must not have more significant bits
       than the width indicated by the maxval.

       For a shifting operation, the shift count you specify must not be greater than  the  width
       indicated by the maxval.

       The maxval of the output image is the same as that of the input image.

SEE ALSO
       ppmdim(1) , ppmbrighten(1) , pamdepth(1) , pamarith(1) , pamsummcol(1) , pamsumm(1) , ppm-
       fade(1) , pnminvert(1) , pam(1) , pnm(1) ,

HISTORY
       This program was added to Netpbm in Release 10.3 (June 2002).

netpbm documentation			    July 2007			   Pamfunc User Manual(0)
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