php regex or preg_match colorbox (jQuery)

i have an ads site where images are located and named as the follow:

images/139/16_2_139.jpg

where: -

images/139/ is the users folder
16 is the id of ad
2 is the number of images available for this ad
139 is the user id

examples

images/1390/3800_12_1390.jpg
images/27/728_7_27.jpg
images/8563/13281_2_8563.jpg

Now I need to display every images concerning this ad in a slideshow (colorbox)

i extract the ad id and the user id from sql

i need that php read in the directory every images concerning the ad id and the user id and display it in colorbox slideshow (jQuery addon) the ad id goes from 1 to 15000 and the user id goes from 1 to 9000 and can also be more

i dont know if better regex or preg_match can solve my problem

thanks for your help

Solution

i found myself a solution who work i share for reference:

function microtime_float()
{
   list($usec, $sec) = explode(' ', microtime());

   return ((float)$usec + (float)$sec);
}
ini_set ("display_errors", "1");
error_reporting(E_ALL);
$start = microtime_float();
$b = '<br />';  $ad = 16;   $cust = 139;
$directory = $_SERVER['DOCUMENT_ROOT'].'/ginew/advertiser/images/'. $cust .'/';
// echo $directory;
if( is_dir( $directory ) ) {
$handler = opendir( $directory );
    $images = glob("$directory{*.jpg,*.JPG,*jpeg, *JPEG}", GLOB_BRACE);
    $cnt = count($images);
echo 'total images in directory: '. $cnt.$b;

$i=0;   $img1 = '';
while ($filename = readdir($handler)) {
    if($filename != '.' && $filename != '..') {
        $base = basename($filename, ".jpg"); // echo $base.$b;
        $ext = substr(strrchr($filename, '.'), 0); // echo $ext.$b;
        $imgsize = @filesize($directory.$filename); $imgsize =     ($imgsize/1000000) .' mb';
if ( preg_match( '#'.$ad.'_([0-9]+)_'.$cust.'#', $base, $matches ) ) { 
$i++;
 $img = $i .' matches '. $matches[0] . $ext; 
$img1.= $i .' matches '. $matches[1] .'<br>'; 

 echo $img.$b;
        } // END is_dir
          echo $i .' --> '. $filename . $ext .' => '. $imgsize .'<br />';
    } // END preg_match
} // END if filename
$end = microtime_float();
} // END while
echo '/ -------------------------- /<br>';
echo $img1.$b;
echo 'matches images found: '. $i . $b;
echo 'preg_match brauch : '.($end-$start).' Sekonnen';

output:
total images in directory: 6
1 matches 16_2_139.jpg
2 matches 16_7_139.jpg
3 matches 16_1_139.jpg
/ -------------------------- /
1 matches 2
2 matches 7
3 matches 1

matches images found: 3
preg_match brauch : 0.00037693977355957 Sekonnen

if anybody has a better solution for this please post it thanks to everyone ;-)