Scientist: Mark Showalter
Opus contains a lot of unedited pictures of ringed solar system bodies (and many that are not ringed). To find interesting images, use the filters to narrow down the search a bit, then click "Browse results". Clicking on an image will pop up a dialog with a larger image, and then the image can be saved using the browser's "Save image" functionality. To change the search, click the "Search" button in the upper-left instead of using the back button. The color of the thumbnail indicates the spectrum the camera captured; all images are grayscale.
Opus also has an HTML REST API that could be easily programmatically interpreted. It uses the same query string format as the search tool to select the set of images. Construct the urls manually, like: http://pds-rings-tools.seti.org/opus/api/images/med.html?planet=Saturn&target=ATLAS