Conditional image-to-video (cI2V) generation aims to synthesize a new
plausible video starting from an image (e.g., a person's face) and a condition
(e.g., an action class label like smile). The key challenge of the cI2V task
lies in the simultaneous generation of realistic spatial appearance and
temporal dynamics corresponding to the given image and condition. In this
paper, we propose an approach for cI2V using novel latent flow diffusion models
(LFDM) that synthesize an optical flow sequence in the latent space based on
the given condition to warp the given image. Compared to previous
direct-synthesis-based works, our proposed LFDM can better synthesize spatial
details and temporal motion by fully utilizing the spatial content of the given
image and warping it in the latent space according to the generated
temporally-coherent flow. The training of LFDM consists of two separate stages:
(1) an unsupervised learning stage to train a latent flow auto-encoder for
spatial content generation, including a flow predictor to estimate latent flow
between pairs of video frames, and (2) a conditional learning stage to train a
3D-UNet-based diffusion model (DM) for temporal latent flow generation. Unlike
previous DMs operating in pixel space or latent feature space that couples
spatial and temporal information, the DM in our LFDM only needs to learn a
low-dimensional latent flow space for motion generation, thus being more
computationally efficient. We conduct comprehensive experiments on multiple
datasets, where LFDM consistently outperforms prior arts. Furthermore, we show
that LFDM can be easily adapted to new domains by simply finetuning the image
decoder. Our code is available at this https URL

本文提出了一种使用基于新颖潜在流扩散模型（LFDM）的方法，旨在从给定的图像和条件（例如笑容）中合成一个新的合理视频，该模型可以更好地综合空间细节和时间动作。