Typing in keywords to search will return images sorted by the
following formula: 1 - Nm/Nq where Nm is the
number of keywords that match query set and image set,
and Nq is the
number of keywords in the query set.
Example: If you type in "dog" and "house"
and hit enter, images with descriptors "dog" and "house" will be
displayed first, followed by images that have only "dog" or only
"house".