A DOI (= Digital Object Identifier) allows the unique designation of a (digital) object. Unlike a URL that can change, the DOI is a permanent identifier always resolving to the corresponding document. For this reason, the citability is guaranteed. Further information on the DOI can be found on the website of ETH Zurich’s DOI Desk.
Digital images have to be citable easily. This is possible with a DOI. The DOI does not refer directly to the image, but to the entry in the catalogue (landingpage). All publicly accessible images on E-Pics may therefore get a DOI (if desired), provided that the catalogue owner commits himself to ensure that the images are permanently and unmodified available online. Moreover, the metadata required for the DOI registration needs to be present. The DOI appears in an additional record field. If a new image is uploaded to E-Pics, a DOI is automatically assigned by means of a specific status. Once a day these DOIs are registered and consequently the image can be cited with the corresponding DOI. If the images are exported to Google, the DOI is visible there as well. Unlike the direct link, it never changes. For customers at ETH Zurich, the assignment of DOIs is free.