#!/usr/local/bin/perl # rlumin.pl - Generate color relative luminance chart # Copyright 2015 David Meyer +JMJ # (License and documentation at bottom of file.) # Source: Ben Caldwell et al. ed. Web Content Accessibility # Guidelines (WCAG) 2.0. World Wide Web Consortium (W3C). # December 11, 2008. # # accessed January 7, 2015. use strict; use warnings; our %bytesc = ( 0 => 0, 17 => 1, 68 => 4, 119 => 7, 187 => 11, 255 => 15 ); our(@color, %rlumin); sub colorsc { my($r, $g, $b) = @_; return sprintf("#%x%x%x", $bytesc{$r}, $bytesc{$g}, $bytesc{$b}); } sub lumc { my($c) = @_; my $cn = $c/255; if ($cn <= .03928) {return $cn/12.92;} else {return (($cn+.055)/1.055)**2.4;} } sub rlumin { my($r, $g, $b) = @_; return .2126 * lumc($r) + .7152 * lumc($g) + .0722 * lumc($b); } our($r, $g, $b); for $r (0, 17, 68, 119, 187, 255) { for $g (0, 17, 68, 119, 187, 255) { for $b (0, 17, 68, 119, 187, 255) { my $colorsc = colorsc($r, $g, $b); push @color, $colorsc; $rlumin{$colorsc} = rlumin($r, $g, $b); } } } our @lcolor = sort {$rlumin{$a} <=> $rlumin{$b}} @color; print "\n

$c $rlumin{$c}

\n\n"; exit 0 __END__ # Documentation ##################################################### =head1 NAME template.pl - Perl script template (command line) =head1 SYNOPSIS/USAGE =head1 DESCRIPTION Mark up code elements with C<>, file names with F<> (or C<> for readability), command names with B<>. Also I<> for italics, U<> for underline. Entities: E ('<'), E ('>'). =head1 OPTIONS =item B<-o> I, B<--option>=I =head1 RETURN VALUE =head1 ERRORS =head1 DIAGNOSTICS =head1 EXAMPLES =head1 ENVIRONMENT =over 6 =item VARIABLE Description of usage of environment variable C. =back =head1 FILES =head1 BUGS, LIMITATIONS, AND CAVEATS =head1 NOTES =head1 AUTHOR David Meyer =head1 HISTORY =head1 COPYRIGHT AND LICENSE Copyright 201x David Meyer =head1 SEE ALSO # Emacs control ##################################################### #Local variables: #mode: perl #End: