Guest editorial: Event-based video analysis/retrieval

Identification of events from visual cues is in general an arduous task because of complexmotion, cluttered backgrounds, occlusions, and geometric and photometric variations of the physical objects. This is even more challenging in case of detection of a logical chain of events, i.e., of a sequence of events called a workflow, and in case of the presence of multiple workflows of events in the environment, able to interact one with the other and affect one the outcome of the other. The recent research advances in computer vision and pattern recognition society have stimulated the development of a series of innovative algorithms, tools and methods for salient object detection and tracking in still images/video streams. These techniques are framed with appropriate descriptors (usually with invariance properties) such as the Scale-Invariant Feature Transform (SIFT) or the Speeded Up Robust Features (SURF), or the MPEG-7 visual descriptors. All these research methods can be considered as initial steps towards the ultimate goal for behavior/event understanding. However, automatic comprehension of someone’s behavior within a scene or even automatic supervision of workflows (e.g., industrial processes) is a complex research field of great attention but with limited results so far. Most of the current approaches presented involve machine learning theories, such as supervised or semi-supervised methods, object tracking algorithms, adaptation mechanisms to handle complex, dynamic and abrupt visual conditions and application-specific analysis topics. On the other hand, during the past few years, more and more people have been coping with the so called “Information Overload” phenomenon. On the basis of the i) diversity and plenitude of media information currently available on the web and ii) the gradual but quick role shift of the users from being solely content consumers to acting both as content consumers Multimed Tools Appl (2014) 69:247–251 DOI 10.1007/s11042-013-1726-z