Deep unsupervised part-whole relational visual saliency

Deep Supervised Salient Object Detection (SSOD) excessively relies on large-scale annotated pixel-level labels which consume intensive labour acquiring high quality labels. In such precondition, deep Unsupervised Salient Object Detection (USOD) draws public attention. Under the framework of the existing deep USOD methods, they mostly generate pseudo labels by fusing several hand-crafted detectors' results. On top of that, a Fully Convolutional Network (FCN) will be trained to detect salient regions separately. While the existing USOD methods have achieved some progress, there are still challenges for them towards satisfactory performance on the complex scene, including (1) poor object wholeness owing to neglecting the hierarchy of those salient regions; (2) unsatisfactory pseudo labels causing by unprimitive fusion of hand-crafted results. To address these issues, in this paper, we introduce the property of part-whole relations endowed by a Belief Capsule Network (BCNet) for deep USOD, which is achieved by a multi-stream capsule routing strategy with a belief score for each stream within the CapsNets architecture. To train BCNet well, we generate high-quality pseudo labels from multiple hand-crafted detectors by developing a consistency-aware fusion strategy. Concretely, a weeding out criterion is first defined to filter out unreliable training samples based on the inter-method consistency among four hand-crafted saliency maps. In the following, a dynamic fusion mechanism is designed to generate high-quality pseudo labels from the remaining samples for BCNet training. Experiments on five public datasets illustrate the superiority of the proposed method. Codes have been released on: https://github.com/Mirlongue/Deep-Unsupervised-Part-Whole-Relational-Visual-Saliency.