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pfsgamma(1)		    General Commands Manual		   pfsgamma(1)

NAME
       pfsgamma	- Apply	gamma correction to color or gray-scale	images

SYNOPSIS
       pfsgamma	[--gamma <gamma> | --inverse-gamma <inv-gamma>]	[--mul <multi-
       plier>]

DESCRIPTION
       Use this	command	to gamma correct a stream of pfs images. Gamma correc-
       tion  is	equivalent to raising value of R, G and	B (or Y	for gray-scale
       images) channels	to 1/gamma power. More information on gamma correction
       can be found at:

       http://www.poynton.com/notes/colour_and_gamma/GammaFAQ.html

       This  command  can work on color	images,	in which case XYZ channels are
       transformed to RGB space, then they are gamma corrected before they are
       converted  back	to  XYZ.  For gray-scale images	(only Y	channel	and XZ
       missing)	gamma correction is applied only to Y channel.

       Data can	be multiplied by an optional multiplier	before	gamma  correc-
       tion.

       Note:  gamma  correction	will set the 'LUMINANCE' tag to	'DISPLAY' thus
       cancelling any sRGB correction when saving  to  LDR  files  (like  PPM,
       TIFF). This will	also cause a warning message when saving to HDR	files,
       because the intensities after gamma correction are not linearly related
       to luminance any	more.

OPTIONS
       --gamma <gamma>,	-g <gamma>
	      Perform  gamma correction	(input^(1/gamma)). This	can be used to
	      convert images from relative luminance or	radiance to pixel val-
	      ues. Default value: 1.0

       --inverse-gamma <inv-gamma>, -i <inv-gamma>
	      Perform  inverse	gamma  correction (input^(gamma)). This	can be
	      used to convert images from pixel	values to relative radiance or
	      luminance.

       --mul <mul>, -m <mul>
	      Multiply	data  by  this	value before gamma correction. Default
	      value: 1

EXAMPLES
       pfsin memorial.hdr | pfsgamma -g	1.8 -m 10 | pfsout memorial_gc.ppm

	      Multiply memorial	image by 10, gamma  correct  it	 and  save  to
	      memorial_gc.ppm.

SEE ALSO
       pfsin(1)	pfsout(1) pfsdisplayfunction(1)

BUGS
       Please  report  bugs  and  comments  to	the  pfstools discussion group
       (http://groups.google.com/group/pfstools).

								   pfsgamma(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | BUGS

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