1 package Shiar_Sheet::Colour;
9 # ITU-R recommendation 601 luma co-efficients
12 our $kg = 1 - $kb - $kr;
16 my @rgb = @_ >= 3 ? @_ : (map {hex} $_[0] =~ /(..)/g);
21 # perceived brightness
22 my ($r, $g, $b) = @{ $_[0] };
23 return $r*$kr + $g*$kg + $b*$kb;
28 $str .= sprintf '%X', min($_ / 17 + .5, 15) for @{ $_[0] };
34 $str .= sprintf '%02X', $_ for @{ $_[0] };