NAME

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

SYNOPSIS

       pfsgamma [--gamma <gamma> | --inverse-gamma <inv-gamma>] [--mul <multiplier>]

DESCRIPTION

       Use this command to gamma correct a stream of pfs images. Gamma correction 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 correction.

       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 values. 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)