1 package Shiar_Sheet::Colour;
11 my @rgb = @_ >= 3 ? @_ : (map {hex} $_[0] =~ /(..)/g);
16 # perceived brightness (using ITU-R recommendation 601 luma co-efficients)
17 my ($r, $g, $b) = @{ $_[0] };
18 return $r*.299 + $g*.587 + $b*.114;
23 $str .= sprintf '%X', min($_ / 17 + .5, 15) for @{ $_[0] };
29 $str .= sprintf '%02X', $_ for @{ $_[0] };