1Pambrighten User Manual(0) Pambrighten User Manual(0)
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6 pambrighten - change a PPM image's Saturation and Value
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10 pambrighten [-saturation=[+|-saturation_percent]]
11 [-value=[+|-value_percent]] netpbmfile
12 Minimum unique abbreviation of option is acceptable. You may use dou‐
14 ble hyphens instead of single hyphen to denote options. You may use
15 white space in place of the equals sign to separate an option name from
16 its value.
17
20 This program is part of Netpbm(1).
21 pambrighten increases or decreases the Saturation and Value (from the
23 HSV color space) of each pixel of a Netpbm image. You specify the per‐
24 centage change for each of those parameters.
25 You can also remap the colors of the pixels so their Values cover the
27 full range of possible Values.
28 The output format is the same as the input format and any extra chan‐
30 nels, such as transparency, are passed through.
31 Hue-Saturation-Value, or HSV, is one way to represent a color, like the
34 more well-known RGB. Hue, Saturation, and Value are numbers in the
35 range from 0 to 1. We always capitalize them in this document when we
36 mean the number from the HSV color space, especially since "value" as a
37 conventional English word has a much more abstract meaning.
38 Value is a measure of how bright the color is, relative to some speci‐
40 fied maximum (the Netpbm formats are also defined in terms of a speci‐
41 fied maximum brightness -- For the purposes of this program, they are
42 the same). In particular, it is the brightness of the brightest pri‐
43 mary color component of the color divided by the maximum brightness
44 possible for a component. Zero Value means black. White has full
45 Value.
46 Hue is an indication of the secondary color with the same brightness
48 that most closely approximates the color. A secondary color is made of
49 a combination of at most two of the primary colors.
50 Saturation is a measure of how close the color is to the color indi‐
52 cated by the Hue and Value. A lower number means more light of the
53 third primary color must be added to get the exact color. Full Satura‐
54 tion means the color is a secondary color. Zero Saturation means the
55 color is gray (or black or white). Decreasing the saturation of a
56 color tends to make it washed out.
57 If it is impossible to increase the Value of a pixel by the amount you
59 specify (e.g. the Value is .5 and you specify +200%), pambrighten
60 increases it to full Value instead.
61 If it is impossible to increase the Saturation of a pixel by the amount
63 you specify (e.g. it is already half saturated and you specify +200%),
64 pambrighten increases it to full Saturation instead.
65 For a simpler kind of brightening, you can use pamfunc -multiplier sim‐
67 ply to increase the brightness of each pixel by a specified percentage,
68 clipping each RGB component where the calculated brightness would
69 exceed full brightness. Thus, the brightest colors in the image would
70 change chromaticity in addition to not getting the specified brightness
71 boost. For decreasing brightness, pamfunc should do the same thing as
72 pambrighten.
73 ppmflash does another kind of brightening. It changes the color of
75 each pixel to bring it a specified percentage closer to white. This
76 increases the value and saturation.
77 pambrighten is the same as pambrighten, except that it recognizes the
79 various Netpbm image formats rather than treating them all as PPM. The
80 output format is the same as the input format and extra channels in a
81 PAM image (such as a transparency channel) get passed through.
82 If you want to modify the Hues in the image, use pamhue.
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88 To double the Value of each pixel:
89 pambrighten -value=100
90 To double the Saturation and halve the Value of each pixel:
92 pambrighten -saturation=+100 -value=-50
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96 -value=value_percent
97 This option specifies the amount, as a percentage, by which you
98 want to change the Value of each pixel. It may be negative.
99 -saturation=value_percent
102 This option specifies the amount, as a percentage, by which you
103 want to change the Saturation of each pixel. It may be nega‐
104 tive.
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110 pnmnorm(1), ppmdim(1), pamfunc(1), ppmflash(1), pamaltsat(1), ppm‐
111 brighten(1), pamdepth(1), pnmgamma(1), pamhue(1), ppmhist(1), ppm(1)
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115 pambrighten was new in Netphm 10.86 (March 2019). It was a PAM conver‐
116 sion of the much older ppmbrighten.
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121 Copyright (C) 1990 by Brian Moffet. Copyright (C) 1989 by Jef
122 Poskanzer.
123 Permission to use, copy, modify, and distribute this software and its
125 documentation for any purpose and without fee is hereby granted, pro‐
126 vided that the above copyright notice appear in all copies and that
127 both that copyright notice and this permission notice appear in sup‐
128 porting documentation. This software is provided "as is" without
129 express or implied warranty.
130
132 This manual page was generated by the Netpbm tool 'makeman' from HTML
133 source. The master documentation is at
134 http://netpbm.sourceforge.net/doc/pambrighten.html
136netpbm documentation 12 January 2019 Pambrighten User Manual(0)