CS 2 Fusion: Contrastive learning for Self-Supervised infrared and visible image fusion by estimating feature compensation map

In infrared and visible image fusion (IVIF), prior knowledge constraints established with image-level information often ignore the identity and differences between source image features and cannot fully utilize the complementary information role of infrared images to visible images. For this purpose, this study develops a Contrastive learning-based Self-Supervised fusion model (CS2Fusion), which considers infrared images as a complement to visible images, and develops a Compensation Perception Network (CPN) to guide the backbone network to generate fusion images by estimating the feature compensation map of infrared images. The core idea behind this method is based on the following observations: (1) there is usually a significant disparity in semantic information between different modalities; (2) despite the large semantic differences, the distribution of self-correlation and saliency features tends to be similar among the same modality features. Building upon these observations, we use self-correlation and saliency operation (SSO) to construct positive and negative pairs, driving CPN to perceive the complementary features of infrared images relative to visible images under the constraint of contrastive loss. CPN also incorporates a self-supervised learning mechanism, where visually impaired areas are simulated by randomly cropping patches from visible images to provide more varied information of the same scene to form multiple positive samples to enhance the model's fine-grained perception capability. In addition, we also designed a demand-driven module (DDM) in the backbone network, which actively queries to improve the information between layers in the image reconstruction, and then integrates more spatial structural information. Notably, the CPN as an auxiliary network is only used in training to drive the backbone network to complete the IVIF in a self-supervised form. Experiments on various benchmark datasets and high-level vision tasks demonstrate the superiority of our CS2Fusion over the state-of-the-art IVIF method.