We all know about Caffeine,which made search results 50% fresher.google confirmed they are working to improve crawling and indexing systems to help people to find recent information on web whether its blog,image or video what ever. Google has announced that "we made some changes to increase the rate at which we update images in our index. These improvements will help people find fresher images in both web and image search." Check this link : http://searchengineland.com/confirmed-google-image-search-updating-index-faster-58448