1. A method comprising: applying predetermined initial sets of rules to an electronic media item to identify content regions within the electronic media item, wherein a first content region is identified as a first region type of a plurality of region types based, at least in part, on a conformance of the first content region to a first predetermined set of rules corresponding to the first region type, the first predetermined set of rules specifying a combination of typographical features used to identify the first region type; and for the first region type: identifying a set of regions of the first region type, wherein the first content region and a second content region in the set of regions are associated with the first region type; analyzing the set of regions to determine a first typographical feature set for the first content region; analyzing the set of regions to determine a second typographical feature set for the second content region; performing a cluster analysis to identify a cluster of regions from the set of regions, the cluster comprising the first content region and the second content region, where the first typographical feature set and the second typographical feature set comprise values that are within a threshold of a desired value for the cluster; updating the first predetermined set of rules corresponding to the first region type to account for typographical feature values determined from a centroid of the cluster of regions to generate a first updated set of rules; and applying the first updated set of rules to the electronic media item to identify one or more regions associated with the first region type.