We propose Framer for interactive frame interpolation, which targets producing smoothly transitioning frames between two images as per user creativity. Concretely, besides taking the start and end frames as inputs, our approach supports customizing the transition process by tailoring the trajectory of some selected keypoints. Such a design enjoys two clear benefits. First, incorporating human interaction mitigates the issue arising from numerous possibilities of transforming one image to another, and in turn enables finer control of local motions. Second, as the most basic form of interaction, keypoints help establish the correspondence across frames, enhancing the model to handle challenging cases (e.g., objects on the start and end frames are of different shapes and styles). It is noteworthy that our system also offers an "autopilot" mode, where we introduce a module to estimate the keypoints and refine the trajectory automatically, to simplify the usage in practice. Extensive experimental results demonstrate the appealing performance of Framer on various applications, such as image morphing, time-lapse video generation, cartoon interpolation, etc. The code, the model, and the interface will be released to facilitate further research.

翻译：我们提出Framer用于交互式帧插值，其目标是根据用户的创意生成两幅图像之间平滑过渡的帧。具体而言，除了将起始帧和结束帧作为输入外，我们的方法支持通过定制选定关键点的运动轨迹来自定义过渡过程。这种设计具有两个明显优势。首先，引入人机交互缓解了从一幅图像变换到另一幅图像时存在的多种可能性所引发的问题，进而实现对局部运动的更精细控制。其次，作为最基本的交互形式，关键点有助于建立跨帧的对应关系，增强模型处理具有挑战性情况的能力（例如，起始帧和结束帧上的物体具有不同的形状和风格）。值得注意的是，我们的系统还提供了一种“自动驾驶”模式，其中我们引入了一个模块来自动估计关键点并优化轨迹，以简化实际使用。大量实验结果表明，Framer在图像变形、延时视频生成、卡通插值等多种应用上均展现出优异的性能。代码、模型及界面将被开源以促进进一步研究。