Existing image fusion algorithms mostly concentrate on the design of network architecture and loss functions, and using unified feature extraction strategies while neglecting the division of redundant and effective information. However, for complementary information, unified feature extractor may not appropriate. Thus, this paper presents a unified image fusion algorithm based on Bézier curves image augmentation and hierarchical decomposition, and a self-supervised learning task is constructed to learn the meaningful information. Where Bézier curves aim to simulate different image features and constructed special self-supervised learning samples, so our method does not require task specific data and can be easily trained on public natural image datasets. Meanwhile, our dual decomposition self-supervised training method can bring redundant information filtering capability to the model. During the decomposition stage, we classify and extract different features of the images and only utilize the extracted effective information in the fusion stage, and the decomposition ability of images provides a foundation for advanced visual tasks, such as image segmentation and object detection. Finally, more detailed and comprehensive fusion images are generated, and the existence of redundant information is effectively reduced. The validity of the proposed method is verified through qualitative and quantitative analysis of multiple image fusion tasks, and our algorithm gets the state-of-the-art results on multiple datasets of different image fusion tasks. The code of our fusion method is available at https://github.com/Yukarizz/DDBFusion.