cgi使えるならこんな感じで行けると思う
動作非確認だけど…

#!/usr/bin/perl

use strict;
use warnings;

my @from= (
'/home/murakami/bin/script/banner/01.png', #-- 0, 6,12,18
'/home/murakami/bin/script/banner/02.png', #-- 1, 7,13,19
'/home/murakami/bin/script/banner/03.png', #-- 2, 8,14,20
'/home/murakami/bin/script/banner/04.png', #-- 3, 9,15,21
'/home/murakami/bin/script/banner/05.png', #-- 4,10,16,22
'/home/murakami/bin/script/banner/06.png', #-- 5,11,17,23
)
my ($hour) = (localtime(time))[2];

print "Content-type: image/png\n\n";
open IMG,$from[$hour];
print <IMG>;
close IMG;