Image left/resize bbcode

I use this bbcode to align a picture left or right. So it look good in a portal.

            $text = preg_replace('#\[img=left\]((ht|f)tps?://)([^\s<"]*?)\[/img\]#e', 'handle_img_tag_left(\'$1$3\')', $text);
            $text = preg_replace('#\[img=right\]((ht|f)tps?://)([^\s<"]*?)\[/img\]#e', 'handle_img_tag_right(\'$1$3\')', $text);

Works great only i want one thing....i want that when somebody use the above bbcode that the picture always goto for example size 80 x 80. And when you click on it you get the large version. Don't know how to this...