移动计算长曝光摄影

摘要

长曝光摄影产生令人惊叹的图像，展示了场景中移动元素的运动模糊。通常有两种模式，分别产生前景或背景的模糊效果。传统上，前景模糊图像是在三脚架相机上拍摄的，展示了模糊的移动前景元素，如柔和的水流或光轨，背景景观则清晰锐利。背景模糊图像，也称为跟焦摄影，是在相机跟踪移动主体时拍摄的，以产生一个清晰的主体图像，背景因相对运动而模糊。这两种技术都极具挑战性，需要额外的设备和高级技能。在本文中，我们描述了一个在手持智能手机相机应用中运行的计算爆发摄影系统，可以在按下快门按钮时完全自动实现这些效果。我们的方法首先检测并分割显著的主体。我们跟踪多帧的场景运动并对图像进行对齐，以保留所需的清晰度并产生美学上令人愉悦的运动轨迹。我们拍摄一组曝光不足的连拍，并选择能产生控制长度模糊轨迹的输入帧子集，无论场景或相机运动速度如何。我们预测帧间运动并合成运动模糊，填补输入帧之间的时间间隙。最后，我们将模糊图像与清晰的常规曝光合成，以保护面部或几乎不动的场景区域的清晰度，并生成最终的高分辨率和高动态范围（HDR）照片。我们的系统使此前仅供专业人士使用的能力民主化，并使这种创意风格对大多数业余摄影师可及。更多信息和补充材料可在我们的项目网页找到：https://motion-mode.github.io/

English

Long exposure photography produces stunning imagery, representing moving elements in a scene with motion-blur. It is generally employed in two modalities, producing either a foreground or a background blur effect. Foreground blur images are traditionally captured on a tripod-mounted camera and portray blurred moving foreground elements, such as silky water or light trails, over a perfectly sharp background landscape. Background blur images, also called panning photography, are captured while the camera is tracking a moving subject, to produce an image of a sharp subject over a background blurred by relative motion. Both techniques are notoriously challenging and require additional equipment and advanced skills. In this paper, we describe a computational burst photography system that operates in a hand-held smartphone camera app, and achieves these effects fully automatically, at the tap of the shutter button. Our approach first detects and segments the salient subject. We track the scene motion over multiple frames and align the images in order to preserve desired sharpness and to produce aesthetically pleasing motion streaks. We capture an under-exposed burst and select the subset of input frames that will produce blur trails of controlled length, regardless of scene or camera motion velocity. We predict inter-frame motion and synthesize motion-blur to fill the temporal gaps between the input frames. Finally, we composite the blurred image with the sharp regular exposure to protect the sharpness of faces or areas of the scene that are barely moving, and produce a final high resolution and high dynamic range (HDR) photograph. Our system democratizes a capability previously reserved to professionals, and makes this creative style accessible to most casual photographers. More information and supplementary material can be found on our project webpage: https://motion-mode.github.io/

移动计算长曝光摄影

Computational Long Exposure Mobile Photography

摘要

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