1Pamfunc User Manual(0) Pamfunc User Manual(0)
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6 pamfunc - Apply a simple monadic arithmetic function to a Netpbm image
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10 pamfunc { -multiplier=realnum | -divisor=realnum | -adder=integer |
11 -subtractor=integer | -min=wholenum | -max=wholenum -andmask=hexmask
12 -ormask=hexmask -xormask=hexmask -not -shiftleft=count
13 -shiftright=count } [filespec]
14 All options can be abbreviated to their shortest unique prefix. You
16 may use two hyphens instead of one. You may separate an option name
17 and its value with white space instead of an equals sign.
18
21 This program is part of Netpbm(1).
22 pamfunc reads a Netpbm image as input and produces a Netpbm image as
24 output, with the same format, maxval, and dimensions as the input.
25 pamfunc applies a simple transfer function to each sample in the input
26 to generate the corresponding sample in the output. The options deter‐
27 mine what function.
28 pamarith is the same thing, except only for PNM images, for binary
30 functions -- it takes two PNM images as input and applies a specified
31 simple arithmetic function (e.g. addition) on pairs of samples from the
32 two to produce the single output image.
33
37 -multiplier=realnum
38 This option makes the transfer function that of multiplying by
40 realnum. realnum must be nonnegative. If the result
41 is greater than the image maxval, it is clipped to the max‐
42 val.
43 Where the input is a PGM or PPM image, this has the effect of
45 dimming or brightening it. For a different kind of bright‐
46 ening,
47 see ppmbrighten(1)and ppmflash(1)
48 Also, see ppmdim(1),whichdoesthe
50 same thing as pamfunc -multiplier on a PPM image with a
51 multiplier between 0 and 1,
52 except it uses integer arithmetic, so it may be faster.
53 And ppmfade(1)cangenerateawhole
55 sequence of images of brightness declining to black or
56 increasing to
57 white, if that's what you want.
58 -divisor=realnum
61 This option makes the transfer function that of dividing by
63 realnum. realnum must be nonnegative. If the result
64 is greater than the image maxval, it is clipped to the max‐
65 val.
66 This is the same function as you would get with -multiplier,
68 specifying the multiplicative inverse of realnum.
69 -adder=integer
72 This option makes the transfer function that of adding
74 wholenum. If the result is greater than the image maxval,
75 it is clipped to the maxval. If it is less than zero, it
76 is
77 clipped to zero.
78 Note that in mathematics, this entity is called an 'addend,'
80 and an 'adder' is a snake. We use 'adder' because
81 it makes more sense.
82 -subtractor=integer
85 This option makes the transfer function that of subtracting
87 wholenum. If the result is greater than the image maxval,
88 it is clipped to the maxval. If it is less than zero, it
89 is
90 clipped to zero.
91 Note that in mathematics, this entity is called a
93 'subtrahend' rather than a 'subtractor.' We
94 use 'subtractor' because it makes more sense.
95 This is the same function as you would get with -adder,
97 specifying the negative of integer.
98 -min=wholenum
101 This option makes the transfer function that of taking the
103 maximum of the argument and wholenum. I.e the minimum
104 value in the output will be wholenum.
105 If wholenum is greater than the maxval, though, every sam‐
107 ple
108 in the output will be maxval.
109 -max=wholenum
112 This option makes the transfer function that of taking the
114 minimum of the argument and wholenum. I.e the maximum
115 value in the output will be wholenum.
116 If wholenum is greater than the maxval, the function is
118 idempotent -- the output is identical to the input.
119 -andmask=hexmask
122 This option makes the transfer function that of bitwise anding
124 with hexmask.
125 hexmask is in hexadecimal. Example: 0f
127 See section Maxval ⟨#maxval⟩ for the special
129 meaning of maxval with respect to bit string operations
130 such as
131 this.
132 This option was new in Netpbm 10.40 (September 2007).
134 -ormask=hexmask
137 This option makes the transfer function that of bitwise
139 inclusive oring with hexmask.
140 This is analogous to -andmask.
142 This option was new in Netpbm 10.40 (September 2007).
144 -xormask=hexmask
147 This option makes the transfer function that of bitwise
149 exclusive oring with hexmask.
150 This is analogous to -andmask.
152 This option was new in Netpbm 10.40 (September 2007).
154 -not
157 This option makes the transfer function that of bitwise logical
159 inversion (e.g. sample value 0xAA becomes 0x55).
160 See section Maxval ⟨#maxval⟩ for the special
162 meaning of maxval with respect to bit string operations
163 such as
164 this.
165 pnminvert does the same thing for a bilevel visual image
167 which has maxval 1 or is of PBM type.
168 This option was new in Netpbm 10.40 (September 2007).
170 -shiftleft=count
173 This option makes the transfer function that of bitwise shifting
175 left by count bits.
176 See section Maxval ⟨#maxval⟩ for the special
178 meaning of maxval with respect to bit string operations
179 such as
180 this.
181 This option was new in Netpbm 10.40 (September 2007).
183 -shiftright=count
186 This option makes the transfer function that of bitwise shifting
188 right by count bits.
189 This is analogous to -shiftleft.
191 This option was new in Netpbm 10.40 (September 2007).
193
198 For the arithmetic functions, the maxval has no meaning. The function
199 applies to the sample value as an integer. (Note that this differs
200 from the usual interpretation of PAM samples as being a fraction of a
201 maxval, but does produce more intuitive result: 2 times 5 is 10.
202 But with the bit string operations, the maxval has a special meaning.
204 The functions in question are: -andmask, -ormask, -xormask, -not,
205 -shiftleft, and -shiftright.
206 With these, each sample value the input image, and in the output image,
208 represents a bit string, not a number. The maxval tells how wide the
209 bit string is. The maxval must be a full binary count (a power of two
210 minus one, such as 0xff) and the number of ones in it is the width of
211 the bit string.
212 For a masking function, the mask value you specify must not have more
214 significant bits than the width indicated by the maxval.
215 For a shifting operation, the shift count you specify must not be
217 greater than the width indicated by the maxval.
218 The maxval of the output image is the same as that of the input image.
220
224 ppmdim(1), ppmbrighten(1), pamdepth(1), pamarith(1), pamsummcol(1),
225 pamsumm(1), ppmfade(1), pnminvert(1), pam(1), pnm(1),
226
229 This program was added to Netpbm in Release 10.3 (June 2002).
230netpbm documentation July 2007 Pamfunc User Manual(0)