NAME

       PDL::Graphics::LUT - provides access to a number of look-up tables

SYNOPSIS

        use PDL::Graphics::PGPLOT;
        use PDL::Graphics::LUT;

        # what tables are available
        my @tables = lut_names();

        # get the reversed colour table 'smooth',
        # with the gamma intensity ramp
        my ( $l, $r, $g, $b ) = lut_data( 'smooth', 1, 'gamma' );

        # use the table idl5 in ctab
        ctab( lut_data('idl5') );

DESCRIPTION

       PDL::Graphics::LUT contains a number of colour look-up tables (in rgb format) and
       intensity ramps, and provides routines to access this data.  The format of the data is
       suitable for use by ctab.

       Unlike the initial release of the package, the data tables are now stored within the PDL
       distribution as FITS files (see $tabledir and $rampdir), rather than in the module itself.
       Changes to these directories will be picked up on the next call to one of the package
       functions.

FUNCTIONS

   lut_names()
       Return, as a list, the names of the available colour tables.

        @tables = lut_names();

   lut_ramps()
       Return, as a list, the names of the available intensity ramps.

        @ramps = lut_ramps();

   lut_data()
       Load in the requested colour table and intensity ramp.

        ( $l, $r, $g, $b ) = lut_data( $table, [ $reverse, [ $ramp ] ] );

       Returns the levels and r, g, b components of the colour table $table. If $reverse is 1
       (defaults to 0 if not supplied), then the r, g, and b components are reversed before being
       returned.  If not supplied, $ramp defaults to "ramp" (this is a linear intensity ramp).

       The returned values are piddles containing values in the range 0 to 1 inclusive, and are
       floats.

VARIABLES

   $tabledir
       The directory in which the colour tables (in rgb format) are stored.

   $rampdir
       The directory in which the intensity ramps are stored.

   $suffix
       The suffix for the data files in $tabledir and $rampdir.

FURTHER INFORMATION

       The colour tables were taken from the STARLINK GAIA package, and are provided under the
       GNU copyleft.  See http://star-www.rl.ac.uk/ and http://star-www.dur.ac.uk/~pdraper/ for
       more details.

AUTHOR

       Doug Burke (djburke@cpan.org), with thanks to Peter Draper/STARLINK for providing the
       colour-table data, and Christian Soeller and Karl Glazebrook for their help.

       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.