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Pambrighten User Manual(0)			    Pambrighten	User Manual(0)

       pambrighten - change a PPM image's Saturation and Value

       pambrighten			 [-saturation=[+|-saturation_percent]]
       [-value=[+|-value_percent]] netpbmfile

       Minimum unique abbreviation of option is	acceptable.  You may use  dou-
       ble  hyphens  instead  of single	hyphen to denote options.  You may use
       white space in place of the equals sign to separate an option name from
       its value.

       This program is part of Netpbm(1).

       pambrighten  increases  or decreases the	Saturation and Value (from the
       HSV color space)	of each	pixel of a Netpbm image.  You specify the per-
       centage change for each of those	parameters.

       You  can	 also remap the	colors of the pixels so	their Values cover the
       full range of possible Values.

       The output format is the	same as	the input format and any  extra	 chan-
       nels, such as transparency, are passed through.

       Hue-Saturation-Value, or	HSV, is	one way	to represent a color, like the
       more well-known RGB.  Hue, Saturation, and Value	 are  numbers  in  the
       range  from 0 to	1.  We always capitalize them in this document when we
       mean the	number from the	HSV color space, especially since "value" as a
       conventional English word has a much more abstract meaning.

       Value  is a measure of how bright the color is, relative	to some	speci-
       fied maximum (the Netpbm	formats	are also defined in terms of a	speci-
       fied  maximum  brightness -- For	the purposes of	this program, they are
       the same).  In particular, it is	the brightness of the  brightest  pri-
       mary  color  component  of  the color divided by	the maximum brightness
       possible	for a component.  Zero Value  means  black.   White  has  full

       Hue  is	an  indication of the secondary	color with the same brightness
       that most closely approximates the color.  A secondary color is made of
       a combination of	at most	two of the primary colors.

       Saturation  is  a  measure of how close the color is to the color indi-
       cated by	the Hue	and Value.  A lower number means  more	light  of  the
       third primary color must	be added to get	the exact color.  Full Satura-
       tion means the color is a secondary color.  Zero	Saturation  means  the
       color  is  gray	(or  black  or white).	Decreasing the saturation of a
       color tends to make it washed out.

       If it is	impossible to increase the Value of a pixel by the amount  you
       specify	(e.g.  the Value is .5 and you specify +200%), pambrighten in-
       creases it to full Value	instead.

       If it is	impossible to increase the Saturation of a pixel by the	amount
       you  specify (e.g. it is	already	half saturated and you specify +200%),
       pambrighten increases it	to full	Saturation instead.

       For a simpler kind of brightening, you can use pamfunc -multiplier sim-
       ply to increase the brightness of each pixel by a specified percentage,
       clipping	each RGB component where the calculated	brightness  would  ex-
       ceed  full  brightness.	 Thus, the brightest colors in the image would
       change chromaticity in addition to not getting the specified brightness
       boost.	For decreasing brightness, pamfunc should do the same thing as

       ppmflash	does another kind of brightening.  It  changes	the  color  of
       each  pixel  to	bring it a specified percentage	closer to white.  This
       increases the value and saturation.

       pambrighten is the same as pambrighten, except that it  recognizes  the
       various Netpbm image formats rather than	treating them all as PPM.  The
       output format is	the same as the	input format and extra channels	 in  a
       PAM image (such as a transparency channel) get passed through.

       If you want to modify the Hues in the image, use	pamhue.

       To double the Value of each pixel:
       pambrighten -value=100

       To double the Saturation	and halve the Value of each pixel:
       pambrighten -saturation=+100 -value=-50

	      This  option specifies the amount, as a percentage, by which you
	      want to change the Value of each pixel.  It may be negative.

	      This option specifies the	amount,	as a percentage, by which  you
	      want  to	change	the Saturation of each pixel.  It may be nega-

       pnmnorm(1),  ppmdim(1),	pamfunc(1),  ppmflash(1),  pamaltsat(1),  ppm-
       brighten(1), pamdepth(1), pnmgamma(1), pamhue(1), ppmhist(1), ppm(5)

       pambrighten was new in Netphm 10.86 (March 2019).  It was a PAM conver-
       sion of the much	older ppmbrighten.

       Copyright (C)  1990  by	Brian  Moffet.	 Copyright  (C)	 1989  by  Jef

       Permission  to  use, copy, modify, and distribute this software and its
       documentation for any purpose and without fee is	hereby	granted,  pro-
       vided  that  the	 above	copyright notice appear	in all copies and that
       both that copyright notice and this permission notice  appear  in  sup-
       porting	documentation.	 This software is provided "as is" without ex-
       press or	implied	warranty.

       This manual page	was generated by the Netpbm tool 'makeman'  from  HTML
       source.	The master documentation is at

netpbm documentation		12 January 2019	    Pambrighten	User Manual(0)


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