使用此:

$string = 'folder1:image1.jpg|folder2:image2.jpg|folder3:image3.jpg';
$imagedata = explode("|", $string);
foreach($imagedata as $image) {
    $img=explode(":", $image);
    echo '<img src="' . $img[0] . '/' . $img[1] . '" /><br />';
}