Wordpress custom code to display latest image

am currently query_posts to grab the latest posts thumbs and displaying them on the home page as such

<ul class="theteam">
<?php query_posts( 'posts_per_page=4&cat=-12'); ?>
<?php while (have_posts()) : the_post(); ?>

<?php   /*get the thumb image*/
    $imgs = get_the_post_thumbnail($id,'medium');

    /*get the img URL, delete the <img /> tag */    

    $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $imgs, $matches);

    /*the image URL*/

    $img = $matches [1] [0];
?>

<li class="figure">
    <a href="<?php the_permalink(); ?>"><img src="<?php echo  $img; ?>" alt="Post image" />
    <div class="figcaption"><span class="cap-left"><?php the_title(); ?></span></div></a>
</li>
<?php endwhile; ?>

PHP:

am also grabbing the title and displaying it with a hover effect over the image when mouse over using css, my question is can i display the image post from 4 different categories? like to display only the last post from these categories.

in image 1 it will always grab from category 1, image 2 from category 4, image 3 from category 2 etc ... or will i have to keep repeating this loop to get he results i need?

Thanks in advance.