PDL::ImageRGB man page on aLinux

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ImageRGB(3)	      User Contributed Perl Documentation	   ImageRGB(3)

NAME
       PDL::ImageRGB -- some utility functions for RGB image data handling

DESCRIPTION
       Collection of a few commonly used routines involved in handling of RGB,
       palette and grayscale images. Not much more than a start. Should be a
       good place to exercise some of the thread/map/clump PP stuff.

       Other stuff that should/could go here:

       ·  color space conversion

       ·  common image filters

       ·  image rebinning

SYNOPSIS
	use PDL::ImageRGB;

FUNCTIONS
       cquant

       quantize and reduce colours in 8-bit images

	   ($out, $lut) = cquant($image [,$ncols]);

       This function does color reduction for <=8bit displays and accepts 8bit
       RGB and 8bit palette images. It does this through an interface to the
       ppm_quant routine from the pbmplus package that implements the median
       cut routine which intellegently selects the 'best' colors to represent
       your image on a <= 8bit display (based on the median cut algorithm).
       Optional args: $ncols sets the maximum nunmber of colours used for the
       output image (defaults to 256).	There are images where a different
       color reduction scheme gives better results (it seems this is true for
       images containing large areas with very smoothly changing colours).

       Returns a list containing the new palette image (type PDL_Byte) and the
       RGB colormap.

       interlrgb

       Make an RGB image from a palette image and its lookup table.

	   $rgb = $palette_im->interlrgb($lut)

       Input should be of an integer type and the lookup table (3,x,...). Will
       perform the lookup for any N-dimensional input pdl (i.e. 0D, 1D, 2D,
       ...). Uses the index command but will not dataflow by default. If you
       want it to dataflow the dataflow_forward flag must be set in the $lut
       piddle (you can do that by saying $lut->set_dataflow_f(1)).

       rgbtogr

       Converts an RGB image to a grey scale using standard transform

	  $gr = $rgb->rgbtogr

       Performs a conversion of an RGB input image (3,x,....) to a greyscale
       image (x,.....) using standard formula:

	  Grey = 0.301 R + 0.586 G + 0.113 B

       bytescl

       Scales a pdl into a specified data range (default 0-255)

	       $scale = $im->bytescl([$top])

       By default $top=255, otherwise you have to give the desired top value
       as an argument to "bytescl". Normally "bytescl" doesn't rescale data
       that fits already in the bounds 0..$top (it only does the type
       conversion if required).	 If you want to force it to rescale so that
       the max of the output is at $top and the min at 0 you give a negative
       $top value to indicate this.

BUGS
       This package doesn't yet contain enough useful functions!

AUTHOR
       Copyright 1997 Christian Soeller <c.soeller@auckland.ac.nz> All rights
       reserved. There is no warranty. You are allowed to redistribute this
       software / documentation under certain conditions. For details, see the
       file COPYING in the PDL distribution. If this file is separated from
       the PDL distribution, the copyright notice should be included in the
       file.

perl v5.10.0			  2008-08-29			   ImageRGB(3)
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