You can view and download the images of your contest participants from the 'Leads' section.
Once on the 'Leads' page, where you can see all the entries, click on the 'View all images' section, on the left sidebar.
It's also possible to download all the original-size images by clicking on that URL, with some kind of browser extension that downloads all the images referenced on a page. We use DownThemAll! for Firefox and Metalink Downloader for Chrome.