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XPAND(9.1)							    XPAND(9.1)

NAME
       xpand, picnegate	- adjust dynamic range

SYNOPSIS
       fb/xpand	[ -s ] [ input ] [ lo hi [ inlo	inhi ] ]

       fb/picnegate [ input ]

DESCRIPTION
       Xpand  linearly adjusts the dynamic range of the	input picture (default
       standard	input) mapping value inlo to lo, and inhi to hi.   Lo  and  hi
       default	to  0 and 255.	If inlo	and inhi are not specified, the	lowest
       and highest pixel values	in the input  image  are  used.	  By  default,
       then,  xpand  expands the image's dynamic range by mapping its smallest
       pixel value to zero and its largest value to 255.  Option -s causes all
       channels	 of  the  input	image to be considered together	when computing
       default values for inlo and inhi, thus preserving the hue of  rgb  pic-
       tures.	Otherwise,  each channel is treated separately.	 Option	-s has
       no effect if inlo and inhi are specified	on the command line.

       There is	no requirement that lo be smaller than hi,  or	that  inlo  be
       smaller	than  inhi,  nor that any of those values be in	the range 0 to
       255.  Output values not in the range 0 to 255 are clamped.   For	 exam-
       ple,	 xpand 0 255 255 0 inverts the pixel values of its input.  For
       convenience, picnegate is a script that executes	this command.

SOURCE
       /sys/src/fb/xpand.c

SEE ALSO
       picfile(9.6)

								    XPAND(9.1)

NAME | SYNOPSIS | DESCRIPTION | SOURCE | SEE ALSO

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