According to a Wikipedia article,
The index is calculated based on the distribution of citations received by a given researcher’s publications. A scientist has index h if h of his Np papers have at least h citations each, and the other (Np – h) papers have at most h citations each.
Applying the same principle to Flickr, your f-index would be calculated based on the number of views received by each of your images. My f-index is currently 73 – meaning I have 73 images on Flickr with at least 73 views each.
What’s your f-index?