JpegRDF "reads and manipulates RDF metadata stored in the comment section of JPEG images. It can extract, query, and augment the data. Manipulating JPEG images with jpegrdf does not modify the actual image data or any other sections of the file." It basically converts the EXIF format (f-stop, camera, flash used, etc.) to RDF. Uses Jena. I'd like to see an ontology based on cameras and the EXIF (or metdata) that they produce.