From co-saliency to co-segmentation: An efficient and fully unsupervised energy minimization model
We address two key issues of co-segmentation over multiple images. The first is whether a pure unsupervised algorithm can satisfactorily solve this problem. Without the user's guidance, segmenting the foregrounds implied by the common object is quite a challenging task, especially when substantial variations in the object's appearance, shape, and scale are allowed. The second issue concerns the efficiency if the technique can lead to practical uses. With these in mind, we establish an MRF optimization model that has an energy function with nice properties and can be shown to effectively resolve the two difficulties. Specifically, instead of relying on the user inputs, our approach introduces a co-saliency prior as the hint about possible foreground locations, and uses it to construct the MRF data terms. To complete the optimization framework, we include a novel global term that is more appropriate to co-segmentation, and results in a submodular energy function. The proposed model can thus be optimally solved by graph cuts. We demonstrate these advantages by testing our method on several benchmark datasets.