Get resized product image without loading product

product image by id

$image = Mage::getResourceModel('catalog/product')->getAttributeRawValue([product_id], 'thumbnail', [store_id]);
$product = new Mage_Catalog_Model_Product;

$imageUrl = (string)Mage::helper('catalog/image')->init($product, 'thumbnail', $image)->resize(100, 100);