As already mentioned in the introduction, visual saliency tries to describe the visual quality of certain objects or items that allows them to grab our immediate attention. Our brains constantly drive our gaze towards the important regions of the visual scene, as if it were to shine a flashlight on different sub-regions of the visual world, allowing us to quickly scan our surroundings for interesting objects and events while neglecting the less important parts.

It is thought that this is an evolutionary strategy to deal with the constant information overflow that comes with living in a visually rich environment. For example, if you take a casual walk through a jungle, you want to be able to notice the attacking tiger in the bush to your left before admiring the intricate color pattern on the butterfly's wings in front of you. As a result, the visually salient objects have the remarkable quality of popping out of their surroundings, much like the target bars in the following...