What is Semantic Gap

The semantic gap characterizes the difference between two descriptions of an object by different linguistic representations, for instance languages or symbols. In computer science, the concept is relevant whenever ordinary human activities, observations, and tasks are transferred into a computational representation (Wikipedia, n.d.f).

The gap between primitive (low-level) features of an image and semantic meanings that people recognize from the image.

The lack of coincidence between the data that one can extract from the visual information and the interpretation that the same data have for a user in a given situation.

The difference between the high-level user perception of the data and the lower-level representation of the data used by computers. As high-level user perception involves semantics which cannot be directly translated into logic context, bridging the semantic gap is considered a challenging research problem.