Use this Regular Expression ~\/\image\/(.*?)\/~
<?php
$str=' Mario Ermito photos by sample.com Mario Ermito Latest News, Photos, Biography, Videos and Wallpapers [img]http://xyz.sample.com/image/4205476/600full-mario-ermito.jpg[/img][img]http://xyz.sample.com/image/4453948/600full-my-profile.jpg[/img][img]http://xyz.sample.com/image/427185/600full-eagle-eye-poster.jpg[/img][img]http://xyz.sample.com/image/1323868/600full-alexis-bledel.jpg[/img][img]http://xyz.sample.com/image/2505314/600full-monroe-lee.jpg[/img][img]http://xyz.sample.com/image/3300481/600full-cindy-crawford.jpg[/img][img]http://xyz.sample.com/image/1046646/600full-pitura-freska.jpg[/img][img]http://xyz.sample.com/image/4322305/600full-kristin-kreuk.jpg[/img][img]http://xyz.sample.com/image/4261476/600full-kang-so--ra.jpg[/img][img]http://xyz.sample.com/image/3386911/600full-summer-brielle.jpg[/img][img]http://xyz.sample.com/image/4663949/600full-the-closer-artwork.jpg[/img]';
preg_match_all('~\/\image\/(.*?)\/~', $str, $matches);
print_r($matches[1]);
OUTPUT :
Array
(
[0] => 4205476
[1] => 4453948
[2] => 427185
[3] => 1323868
[4] => 2505314
[5] => 3300481
[6] => 1046646
[7] => 4322305
[8] => 4261476
[9] => 3386911
[10] => 4663949
)