# pamfunc (1) - Linux Manuals

## pamfunc: Apply a simple monadic arithmetic function to a Netpbm image

## 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 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 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 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 sample 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.

## HISTORY

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

## SEE ALSO

**ppmdim**(1) ,

**ppmbrighten**(1) ,

**pamdepth**(1) ,

**pamarith**(1) ,

**pamsummcol**(1) ,

**pamsumm**(1) ,

**ppmfade**(1) ,

**pnminvert**(1) ,

**pam**(1) ,

**pnm**(1) ,