Make Imagination Clearer! Stable Diffusion-based Visual Imagination for Multimodal Machine Translation

Visual information has been introduced for enhancing machine translation (MT), and its effectiveness heavily relies on the availability of large amounts of bilingual parallel sentence pairs with manual image annotations. In this paper, we propose a stable diffusion-based imagination network integrated into a multimodal large language model (MLLM) to explicitly generate an image for each source sentence, thereby advancing multimodal MT. Particularly, we build heuristic feedback with reinforcement learning to ensure the consistency of the generated image with the source sentence without the supervision of visual information, which breaks the high-cost bottleneck of image annotation in MT. Furthermore, the proposed method enables imaginative visual information to be integrated into text-only MT in addition to multimodal MT. Experimental results show that our model significantly outperforms existing multimodal MT and text-only MT, especially achieving an average improvement of more than 12 BLEU points on Multi30K and MSCOCO multimodal MT benchmarks.