Linux Certif

Toute la documentation sur la certification Linux LPI

pamfunc

NAME

pamfunc - Apply simple arithmetic functions to a Netpbm image

SYNOPSIS

pamfunc { -multiplier=realnum | -divisor=realnum | -adder=integer | -subtractor=integer | -min=wholenum | -max=wholenum } [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, except only for PNM images, for binary functions -- it takes two PNM 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),whichdoesthe
     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)cangenerateawhole
     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 -multiplier,
     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.
     

SEE ALSO

ppmdim(1), ppmbrighten(1), pamdepth(1), pamarith(1), pamsummcol(1), pamsumm(1), ppmfade(1), pam(1), pnm(1),

HISTORY

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