1. An apparatus, comprising: an encoder for joint coding partitions of an image region using frame partitioning and a partition merging procedure, wherein any given one of the partitions that use a coding mode with implicit coding rules is subject to being merged, with another one of the partitions, using a distinct merging rule different than that used for a coding mode with explicit coding rules, wherein the implicit coding rules are ignored and the explicit coding rules are used when a particular one of the partitions, to which the given one of the partitions that uses the coding mode with the implicit coding rules and the other one of the partitions is to be merged, is a first partition, in scanning order, in a segment of at least two merged partitions.