There are so many ways to create loading animation image (loading.gif), we can create it using Adobe Firefox, Adobe Photoshop CS4 and newer or we can create using Online Ajax Loading Generator. My favorite website to create Ajax Loading gif Generator is http://ajaxload.info/ and http://www.preloaders.net/
Two site above easy to use and have so many templates that we can custom. AjaxLoad offering minimal custom and template. On Preloaders.Net more complete loader animation with many format.