Omnidirectional video saliency

When exploring the visual world, humans (and other species) are faced with more information than they are able to process. To overcome this, selective visual attention allows them to gaze rapidly towards objects of interest in the visual environment. This function of the visual system is of high importance and has received a lot of attention from the scientific community. Being able to understand how selective attention works find applications in various fields, such as design, advertising, perceptual coding and streaming, etc., which makes it a highly regarded research topic. In recent years, with the advent of omnidirectional images and videos (ODI, ODV) new challenges are raised compared to traditional 2D visual content. Indeed, with such type of OD content, users are not restricted to explore what is shown to them in a static viewport, but are now able to freely explore the entire visual world around them by moving their head and even in some cases, by moving their entire body. Therefore, in this chapter, the work on the analysis of user behavior as well as the effort done towards modeling selective visual attention and visual exploration in OD images and video will be introduced. This chapter will provide information on the different approaches that have been taken, and key challenges that have been raised compared to traditional 2D contents, allowing the reader to grasp the key work that has been done on the understanding and modeling of the exploration of OD contents.