Over the last week or so I've been playing quite a bit with the flickr interestingness system. Attempting to figure out how it works and what factors figure into the formula, what doesn't and getting an idea of how they are figured and weighted.
The factors I think flickr uses that determine how interesting a photo are. The number of views, the tags, number of comments, notes and number of favorites. Not the actual content of the photo.
Views
The number of views plays a roll but it seems to be one of least important or lightest weighted of the rules. I believe this to be due to the passiveness of and gathering views. It is possible a great number of views in a short period of time could move an image up in the ranks of interestingness but as most images that get a great number of views in a short period of time usually also gather comments and favorites.
Tags
The tags used to describe an image also play a role in the interestingness. The tags are weighted higher than the number of views and image has. The tag it self plays a factor in the score. Which can be observed by adding and removing some words to an image and observing the interestingness move up or down. Some words do not appear to have a measurable effect on the interestingness while others do. A tag may negatively or positively influence the interestingness of an image.
In many cases removing a tag can change the rank of an image, however adding the tag back does may not result in a change, the same can be observed of adding a tag and removing it. I believe to be caused by the activity on the photo causing a refactorization of the overall interestingness score and if necessary re-ranks the image.
Favorite
When a user "faves" an image it increments a counter and essentially bookmarks the image for that user and increments the favorite count for that image. The weight of someone adding a photo as favorite is greater than that of views or tags, but less than the weight of a comment.
My basis for this is the fact that images with the same number of favorites and a similar number of views the one with more comments is found to be more interesting by flickr. In some cases the one with more comments less views and less favorites may be considered by flickr to be more interesting.
Comments
Carry the highest weight. My theory on this is because the user is interacting with the photo and saying something it counts for more, as others will see the comment, rather than just counting as view or marking it as a favorite.
Notes and Time
I haven't play much with the notes and finding their role or weight of notes by self or others on an image. I suspect Notes are similar in weight to the tags as the notes are also used to show or illustrate something in the image with words while highlighting an area of interest.
Time seems to play a factor as well. Images that get several comments and/or faves in a relatively short period of time in many cases can end up as more interesting than others with more views, comments and/or favorites, that have been accumulating more slowly.
Description and Title
Description and Title do not seem to play a major or direct role the interestingness of a photo.
A description and or title of the photo may indirectly influence the interestingness of a photo as they can draw people in from search engines or just by the title or descriptions associated with an image. The Descriptions and titles may draw people in which would increase views and possibly activity on an image, thus changing the interestingness.
Done
I cannot be certain I have identified all the factors of interestingness on flickr but I do believe I have identified the major factors and basic workings.
The factors I have identified, I identified by experimentation and observation of my photo stream and most interesting photos.
Posted by Ben at September 10, 2008 09:01 AM