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.\"
.IX Title "LUT 3pm"
.TH LUT 3pm "2023-06-17" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
PDL::Graphics::LUT \- provides access to a number of look\-up tables
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& use PDL::Graphics::PGPLOT;
\& use PDL::Graphics::LUT;
\&
\& # what tables are available
\& my @tables = lut_names();
\&
\& # get the reversed colour table \*(Aqsmooth\*(Aq,
\& # with the gamma intensity ramp
\& my ( $l, $r, $g, $b ) = lut_data( \*(Aqsmooth\*(Aq, 1, \*(Aqgamma\*(Aq );
\&
\& # use the table idl5 in ctab
\& ctab( lut_data(\*(Aqidl5\*(Aq) );
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
PDL::Graphics::LUT contains a number of colour look-up tables
(in rgb format) and intensity ramps, and provides routines to 
access this data.
The format of the data is suitable for use by
ctab.
.PP
Unlike the initial release of the package, the data tables are
now stored within the \s-1PDL\s0 distribution as \s-1FITS\s0 files
(see \*(L"$tabledir\*(R" and \*(L"$rampdir\*(R"),
rather than in the module itself.
Changes to these directories will be picked up on the next call
to one of the package functions.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.SS "\fBlut_names()\fP"
.IX Subsection "lut_names()"
Return, as a list, the names of the available colour tables.
.PP
.Vb 1
\& @tables = lut_names();
.Ve
.SS "\fBlut_ramps()\fP"
.IX Subsection "lut_ramps()"
Return, as a list, the names of the available intensity ramps.
.PP
.Vb 1
\& @ramps = lut_ramps();
.Ve
.SS "\fBlut_data()\fP"
.IX Subsection "lut_data()"
Load in the requested colour table and intensity ramp.
.PP
.Vb 1
\& my ( $l, $r, $g, $b ) = lut_data( $table, [ $reverse, [ $ramp ] ] );
.Ve
.PP
Returns the levels and r, g, b components of the colour table
\&\f(CW$table\fR. If \f(CW$reverse\fR is 1 (defaults to \fB0\fR 
if not supplied),
then the r, g, and b components are reversed before being 
returned.
If not supplied, \f(CW$ramp\fR defaults to \fB\*(L"ramp\*(R"\fR 
(this is a linear intensity ramp).
.PP
The returned values are ndarrays containing values in the range
0 to 1 inclusive, and are floats.
.SH "VARIABLES"
.IX Header "VARIABLES"
.ie n .SS "$tabledir"
.el .SS "\f(CW$tabledir\fP"
.IX Subsection "$tabledir"
The directory in which the colour tables (in rgb format) 
are stored.
.ie n .SS "$rampdir"
.el .SS "\f(CW$rampdir\fP"
.IX Subsection "$rampdir"
The directory in which the intensity ramps are stored.
.ie n .SS "$suffix"
.el .SS "\f(CW$suffix\fP"
.IX Subsection "$suffix"
The suffix for the data files in \f(CW$tabledir\fR and
\&\f(CW$rampdir\fR.
.SH "FURTHER INFORMATION"
.IX Header "FURTHER INFORMATION"
The colour tables were taken from the \s-1STARLINK GAIA\s0 package,
and are provided under the \s-1GNU\s0 copyleft.
See http://star\-www.rl.ac.uk/ and 
http://star\-www.dur.ac.uk/~pdraper/ for more details.
.SH "AUTHOR"
.IX Header "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.
.PP
All rights reserved. There is no warranty. You are allowed
to redistribute this software / documentation under certain
conditions. For details, see the file \s-1COPYING\s0 in the \s-1PDL\s0
distribution. If this file is separated from the \s-1PDL\s0 distribution,
the copyright notice should be included in the file.