Cinematic L1 Video Stabilization with a Log-Homography Model
authors Arwen Bradley, Jason Klivington, Joseph Triscari, Rudolph van der Merwe
We present a method for stabilizing handheld video that simulates the camera motions cinematographers achieve with equipment like tripods, dollies, and Steadicams. We formulate a constrained convex optimization problem minimizing the ℓ1-norm of the first three derivatives of the stabilized motion. Our approach extends the work of Grundmann et al.  by solving with full homographies (rather than affinities) in order to correct perspective, preserving linearity by working in log-homography space. We also construct crop constraints that preserve field-of-view; model the problem as a quadratic (rather than linear) program to allow for an ℓ2 term encouraging fidelity to the original trajectory; and add constraints and objectives to reduce distortion. Furthermore, we propose new methods for handling salient objects via both inclusion constraints and centering objectives. Finally, we describe a windowing strategy to approximate the solution in linear time and bounded memory. Our method is computationally efficient, running at 300fps on an iPhone XS, and yields high-quality results, as we demonstrate with a collection of stabilized videos, quantitative and qualitative comparisons to  and other methods, and an ablation study.
Photos (on iOS, iPadOS, and macOS) is an integral way for people to browse, search, and relive life's moments with their friends and family. Photos uses a number of machine learning algorithms, running privately on-device, to help curate and organize images, Live Photos, and videos. An algorithm foundational to this goal recognizes people from their visual appearance.