I. Introduction
Humans are able to rapidly orient attention to important areas in visual field and filter out irrelevant information. Such selective process, called as visual attention mechanism, helps humans operate huge amount of visual information in realtime. Visual attention has long been studied in computer vision community dated back to 1990s [1], and shown wide applications such as object segmentation [2], [3], [77], and video summarization [4], to name a few. Integrating attention mechanism into above tasks could allocate limited computation source into the most task-related targets, as well as obtain biologically inspired results.