  Watermarking serves as a widely adopted approach to safeguard media
copyright. In parallel, the research focus has extended to watermark removal
techniques, offering an adversarial means to enhance watermark robustness and
foster advancements in the watermarking field. Existing watermark removal
methods mainly rely on UNet with task-specific decoder branches--one for
watermark localization and the other for background image restoration. However,
watermark localization and background restoration are not isolated tasks;
precise watermark localization inherently implies regions necessitating
restoration, and the background restoration process contributes to more
accurate watermark localization. To holistically integrate information from
both branches, we introduce an implicit joint learning paradigm. This empowers
the network to autonomously navigate the flow of information between implicit
branches through a gate mechanism. Furthermore, we employ cross-channel
attention to facilitate local detail restoration and holistic structural
comprehension, while harnessing nested structures to integrate multi-scale
information. Extensive experiments are conducted on various challenging
benchmarks to validate the effectiveness of our proposed method. The results
demonstrate our approach's remarkable superiority, surpassing existing
state-of-the-art methods by a large margin.
