I. Introduction
Object co-segmentation is the task of extracting common objects as foregrounds in a group of images. Compared to the single image segmentation, where it’s difficult to ascertain what’s foreground, we have a clear-cut definition of what foreground we wish to extract in the object co-segmentation task. Rother et.al. [1] first introduced the concept of co-segmentation by developing a histogram matching method to extract common parts from a pair of images. However, Vicente et.al. [2] were the first to propose that co-segmentation should be about things (or objects) and there is a need to incorporate a measure of objectness in the models. They proposed a Random Forest classifier to find the similarity between a pair of proposed segmentation of objects in each image of a group followed by the A* search algorithm [3] to find the segmented objects with maximum similarity score. The major applications of object co-segmentation include image grouping [4], object recognition [5], and object tracking [6] which are among the fundamental tasks of Computer Vision.