<?php
include 'app/Mage.php';
Mage::app();

$productId = '15362';
$product = Mage::getModel('catalog/product')->load($productId);
$productMediaConfig = Mage::getModel('catalog/product_media_config');

$baseImageUrl = $productMediaConfig->getMediaUrl($product->getImage());
$smallImageUrl = $productMediaConfig->getMediaUrl($product->getSmallImage());
$thumbnailUrl = $productMediaConfig->getMediaUrl($product->getThumbnail());

?>