Flickr and Image pattern-recognition

I enjoyed the opportunity to look into how Flickr tracked patterns within their images here: http://www.asis.org/Bulletin/Oct-07/Beaudoin_OctNov07.pdf

Back in my undergraduate days, I'd often used the site when looking for inspirational images for my creative writing classes, taking advantage of its ability to pull often-unexpected combinations of ideas together and display just the right image for inspiration.

I thought the inclusion of emotion-based tags such as happy, depressed to indicate mood shown in a piece was an interesting choice. While I wouldn't have likely thought to include it myself, much of my use of the site involved finding pieces exhibiting certain moods I wished to evoke in the story I had been writing. Likewise, I hadn't expected to find categorical tags for humor, poesy, or events...even including assassination as an example.
I also found it interesting that one of the tag categories I found most useful in personal use was also the single least-often used category, that being the emotion tag.