Recognition of special types of graphics is an area of intensive
research. A survey of diagrams recognition and
treatment can be found in [11]. UML CDs are a type of diagram
that graphically represents classes and their relationships
to one another. The majority of existing approaches to
UML diagram image classification and understanding were
developed within the scenario of image feature extraction.
This section is aimed at discussing prior research on the
topic, with focus on the fields of image classification and
UML diagram feature extraction.