<?php
					if ( get_post_meta( get_the_ID(), 'portfolio_main_image', false ) ){
						$image_array = get_post_meta( get_the_ID(), 'portfolio_main_image', false );
					}
					if ( $image_array ) {

					foreach ( $image_array as $image ) {
						$thumbimg = wp_get_attachment_image( $image['ID'], 'full');
						echo $thumbimg;
					}
					}
				?>