Abstract
As an image enhancement technology, multi-modal image fusion primarily aims to retain salient information from multi-source image pairs in a single image, generating imaging information that contains complementary features and can facilitate downstream visual tasks. However, dual-stream methods with convolutional neural networks (CNNs) as backbone networks predominantly have limited receptive fields, whereas methods with Transformers are time-consuming, and both lack the exploration of cross-domain information. This study proposes an innovative image fusion model designed for multi-modal images, encompassing pairs of infrared and visible images and multi-source medical images. Our model leverages the strengths of both Transformers and CNNs to model various feature types effectively, addressing both short- and long-range learning as well as the extraction of low- and high-frequency features. First, our shared encoder is constructed based on Transformers for long-range learning, including an intra-modal feature extraction block, an inter-modal feature extraction block, and a novel feature alignment block that handles slight misalignments. Our private encoder for extracting low- and high-frequency features employs a dual-stream architecture based on CNNs, which includes a dual-domain selection mechanism and an invertible neural network. Second, we develop a cross-attention-based Swin Transformer block to explore cross-domain information. In particular, we introduce a weight transformation that is embedded into the Transformer block to enhance the efficiency. Third, a unified loss function incorporating a dynamic weighting factor is formulated to capture the inherent commonalities of multi-modal images. A comprehensive qualitative and quantitative analysis of image fusion and object detection experimental results demonstrates that the proposed method effectively preserves thermal targets and background texture details, surpassing state-of-the-art alternatives in terms of achieving high-quality image fusion and improving the performance in subsequent visual tasks.