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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 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 miss- ing) 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 can- celling 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 in- tensities 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 con- vert images from relative luminance or radiance to pixel values. De- fault 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 lumi- nance. --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 memor- ial_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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