Saliency Detection with a Deeper Investigation of Light Field

Although the light field has been recently recognized helpful in saliency detection, it is not comprehensively explored yet. In this work, we propose a new saliency detection model with light field data. The idea behind the proposed model originates from the following observations. (1) People can distinguish regions at different depth levels via adjusting the focus of eyes. Similarly, a light field image can generate a set of focal slices focusing at different depth levels, which suggests that a background can be weighted by selecting the corresponding slice. We show that background priors encoded by light field focusness have advantages in eliminating background distraction and enhancing the saliency by weighting the light field contrast. (2) Regions at closer depth ranges tend to be salient, while far in the distance mostly belong to the backgrounds. We show that foreground objects can be easily separated from similar or cluttered backgrounds by exploiting their light field depth. Extensive evaluations on the recently introduced Light Field Saliency Dataset (LFSD) [Li et al., 2014], including studies of different light field cues and comparisons with Li et al.'s method (the only reported light field saliency detection approach to our knowledge) and the 2D/3D state-of-the-art approaches extended with light field depth/focusness information, show that the investigated light field properties are complementary with each other and lead to improvements on 2D/3D models, and our approach produces superior results in comparison with the state-of-the-art.