Please help me [Hide Photo]

[v123shine]

I using this code to hide image below 1 august 2012

PHP Code:

if ($post['dateline'] <  1343797200) //If the date is less than August 1, 2012
{
$this->post['message'] = preg_replace("/<img.+?\>/i" , "<img $1 />", $this->post['message']);
} 


Hook location: posbit_diplay_complete

My question is: How to disable image below 1 august 2012 only on category 5, 9, 13, 18, 27.

Please help me, thank you.