Array of images for a gallery

Hi, Im trying to get an array of images all the wordpress posts and all I am getting is the newest image from the last post, not all of them.

global $post;

		$photos = get_children(array('post_parent' => $post->ID, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC') );

		$results = array();

		if ($photos) {
		    foreach ($photos as $photo) {
		    $keys [] = $photo->ID;
		    $captions [] = $photo->post_excerpt;
		    $descriptions [] = $photo->post_content;
		        // get the correct URL for the selected size
		        $results[] = array(image => wp_get_attachment_url($photo->ID, 'full'), title => '', url => '');
		    }
		}
		return str_replace('\/', '/', json_encode($results));
		}

could anyone tell me what is wrong?
thanks