In recent years, there has been notable progress in single-image rain removal, particularly focusing on static data distributions in these approaches. When dealing with data that constantly changes, the challenge of catastrophic forgetting arises, which is quite common and critical in real-world scenarios. To address this, we propose Evolving COmpact Dual Prompt Learning (EcoDPL), an efficient rehearsal-free continual learning deraining framework designed specifically for low-level vision tasks. Specifically, we design two prompt pools at both image and feature levels and insert these prompts into images and embedding tokens, for better knowledge transfer across tasks. Our adaptive weight generation module, P-Fuser, attaches an attention map to each prompt, to adaptively pay attention to different inputs, and get different weights to fuse prompts, making the inserted prompts more flexible with various inputs. Also, we introduce Grad-Tuner, a dictionary learning strategy, to compress knowledge into fewer prompts. This makes the knowledge more compact and provides more space for new prompts to learn new tasks. Our method stands out by leveraging small, learnable prompts for efficient knowledge retention across tasks, not increasing training time or parameters. Furthermore, we present an augmented method that upgrades the distance function γ from simple cosine distance to a more advanced weight generation network. We also employ a fine-tuned dictionary learning technique, compressing knowledge into a more compact form, and enhancing the ability of prompts to learn new tasks. With our new designs, the model becomes more flexible with various inputs and it compresses knowledge into fewer prompts to free up spaces to learn new tasks. Through extensive experiments on various rain removal datasets, our EcoDPL method consistently outperforms previous continual learning techniques. Notably, although EcoDPL is designed for continual learning with changing data, it also performs well with stationary data, proving its robustness and versatility.
Liu et al. (Thu,) studied this question.