#! perl -sw
use strict;

sub min{ $_[0]<$_[1] ? $_[0] : $_[1] }

sub degrade{
    my ($rgb, $degr) = (hex(shift), pop);
    $rgb -= min( $rgb&(0xff<<$_), $degr<<$_ ) for (0,8,16);
    sprintf '%06x', $rgb;
}

my $rgb = "FF9944";

printf 'Degrading %6s by %3d gives %6s%s', $rgb, $_, degrade( $rgb, $_), $/
    for (0x01, 0x0f, 0x10, 0x44, 0x80, 0xcc, 0xee, 0xf0);

__END__
C:\test>204824