where he stayed for 21 years. There he continued work on motion synthesis; motion transitions using spacetime constraints (1996), which allowed seamless and plausible transitions between motion segments for systems with many degrees of freedom such as the human body; motion interpolation (1998), a system for real-time interpolation of parameterized motions; and artist-directed inverse kinematics (2001), which allowed a user to position an articulated character at high frame rates, for real-time applications such as games. In addition, at Microsoft Research, in his groundbreaking and most-cited work, Cohen and colleagues introduced the Lumigraph (1996), a method for capturing and representing the complete appearance—from all points of view—of either a synthetic or real-world object or scene. Building on this work, Cohen published important follow-on papers in view-based rendering (1997), which used geometric information to create views of a scene from a sparse set of images; and unstructured Lumigraph rendering (2001), which generalized light field and view-dependent texture mapping methods in a single framework. In subsequent work, Cohen significantly advanced the state of the art in matting & compositing, with papers on image and video segmentation based on anisotropic kernel mean-shift (2004); video cutout (2004), which preserved smoothness across space and time; optimized color sampling (2005), which improved previous approaches to image matting by analyzing the confidence of foreground and background color samples; and soft scissors (2007), the first interactive tool for high-quality image matting and compositing. Most recently, Cohen has turned his attention to computational photography, publishing numerous highly creative, landmark papers: interactive digital photomontage (2004), for combining parts of photographs in various novel ways; flash/no-flash image pairs (2004), for combining images taken with and without flash to synthesize new higher-quality results than either image alone; panoramic video textures (2005), for converting a panning video over a dynamic scene to a high-resolution continuously playing video; gaze-based photo cropping (2006); multi-viewpoint panoramas (2006), for photographing and rendering very long scenes; the Moment Camera (2007) outlining general principles for capturing subjective moments; joint bilateral upsampling (2007), for fast image enhancement using a down-sampled image; gigapixel images (2007), a means to acquire extremely high-resolution images with an ordinary camera on a specialized mount; deep photo (2008), a system for enhancing casual outdoor photos by combining them with existing digital terrain data; image deblurring (2010), to deblur images captured with camera shake; GradientShop (2010), which unified previous gradient-domain solutions under a single optimization framework; and ShadowDraw