LeftRefill: Filling Right Canvas based on Left Reference through Generalized Text-to-Image Diffusion Model
Authors: Chenjie Cao, Yunuo Cai, Qiaole Dong, Yikai Wang, Yanwei Fu

This paper introduces LeftRefill an innovative approach to efficiently harness large Text-to-Image (T2I) diffusion models for reference-guided image synthesis. As the name implies LeftRefill horizontally stitches reference and target views together as a whole input. The reference image occupies the left side while the target canvas is positioned on the right. Then LeftRefill paints the right-side target canvas based on the left-side reference and specific task instructions. Such a task formulation shares some similarities with contextual inpainting akin to the actions of a human painter. This novel formulation efficiently learns both structural and textured correspondence between reference and target without other image encoders or adapters. We inject task and view information through cross-attention modules in T2I models and further exhibit multi-view reference ability via the re-arranged self-attention modules. These enable LeftRefill to perform consistent generation as a generalized model without requiring test-time fine-tuning or model modifications. Thus LeftRefill can be seen as a simple yet unified framework to address reference-guided synthesis. As an exemplar we leverage LeftRefill to address two different challenges: reference-guided inpainting and novel view synthesis based on the pre-trained StableDiffusion. Codes and models are released at https://github.com/ewrfcas/LeftRefill.