Existed pre-training methods either focus on single-modal tasks or multi-modal tasks, and cannot effectively adapt to each other. They can only utilize single-modal data (i.e. text or image) or limited multi-modal data (i.e. image-text pairs). In this work, we propose a unified-modal pre-training architecture, namely UNIMO, which can effectively adapt to both single-modal and multi-modal understanding and generation tasks. Large scale of free text corpus and image collections can be utilized to improve the capability of visual and textual understanding, and cross-modal contrastive learning (CMCL) is leveraged to align the textual and visual information into a unified semantic space over a corpus of image-text pairs. As the non-paired single-modal data is very rich, our model can utilize much larger scale of data to learn more generalizable representations. Moreover, the textual knowledge and visual knowledge can enhance each other in the unified semantic space. The experimental results show that UNIMO significantly improves the performance of several single-modal and multi-modal downstream tasks.

本文介绍了一种名为UNIMO的统一单模态预训练架构，它可以有效地适应单模态和多模态理解和生成任务，利用大规模自由文本语料库和图像集合来提高视觉和文本理解的能力，并使用跨模态对比学习来将文本和视觉信息对齐到图像 - 文本对的统一语义空间。实验结果表明，UNIMO显著改善了几个单模态和多模态下游任务的性能。

UNIMO：通过跨模态对比学习实现统一模态理解和生成