# RGB format a text document using a highlight colour. 
# RGB 0-255 like HTML 0x00-0xFF
# Output should be valid RTF but YMMV

sub RTFhighlight {
    my ($text, $highlight, $r, $g, $b, $font) = @_;
    $font ||= "Arial";
    $text =~ s/([\\{}])/\\$1/g;  # escape \ and { }
    $text =~ s/\n/\\par\n/g;     # convert \n to \par
    $text =~ s/\b\Q$highlight\E\b/\\cf1 $highlight\\cf0 /g;
    my $header = "{\\rtf1\\ansi\\ansicpg1252\\deff0\\deflang1033{\\fonttbl{\\f0\\fswiss\\fcharset0 $font;}}\n";
    $header   .= "{\\colortbl ;\\red$r\\green$g\\blue$b;}\n";
  return $header.$text;
}

print RTFhighlight("hello be seabe be because", "be", 0, 0, 0xFF);