CADC plus plus : Advanced Consensus-Aware Dynamic Convolution for Co-Salient Object Detection

When given a group of relevant images for co-salient object detection (Co-SOD), humans first summarize consensus cues from the whole group and then search for co-salient objects in each image. Most previous methods do not consider robustness, scalability, or stability in the summarization stage and adopt a simple fusion strategy to fuse consensus and image features in the searching stage. Our work presents a novel consensus-aware dynamic convolution (CADC) model directly from the "summarize and search" perspective to explicitly and effectively perform Co-SOD. For the summarization stage, we extract robust individual image features by a pooling method and integrate them to generate consensus features via self-attention, thus modeling the scalability and stability. Then, we simultaneously learn two types of consensus-aware dynamic kernels, i.e., a common kernel to capture group-wise common knowledge and adaptive kernels to mine image-specific consensus cues. For the second stage, we adopt dynamic convolution to perform object searching. A novel data synthesis strategy is also developed for model training. Although CADC has obtained competitive performance, we argue that incrementally learning dynamic kernels and representations is more intuitive and natural instead of using a simultaneous scheme, thus presenting our CADC++, an extension of CADC. Concretely, we first adopt the common kernel based dynamic convolution to capture coarse common cues as priors and then use the adaptive kernel based dynamic convolution for mining image-specific details. We also propose a recursive guidance strategy to further explore deep interactions among the two kinds of kernels and image features. Besides, we annotate several challenging attributes for Co-SOD datasets and perform attribute-based evaluation and robustness analysis to promote thorough model evaluation for the Co-SOD field. Extensive experimental results on four benchmark datasets verify both the effectiveness and robustness of our proposed method.