用随机光学+传感器快门,单次拍摄实现高动态范围成像。
Single-shot HDR using conventional image sensor shutter functions and optical randomization
- 通过光学随机化让不同区域曝光不同,配合传感器快门特性编码HDR信息。
- 在10%以上像素饱和时性能优于现有方法,8位传感器实测动态范围达73dB。
- 仅需商用传感器和低成本光纤束,适合低成本高动态成像应用。
高动态范围(HDR)成像是克服图像传感器动态范围限制的关键技术。传统方法依赖多次曝光,导致捕获时间变长,在动态场景中易产生运动伪影。单次拍摄HDR通过将HDR数据编码至一次曝光,再通过计算恢复。现有方法依赖强图像先验,难以处理过曝区域。本文利用市售传感器的全局复位释放(GRR)快门模式,该模式使靠近传感器底部的行具有更长曝光时间。结合光学系统将图像随机打乱后投射到传感器上,实现场景内空间随机曝光。利用总变差图像先验求解优化问题,可有效恢复HDR数据。仿真结果表明,当超过10%的传感器像素饱和时,本方法优于其他单次拍摄方法;在仅1%饱和时也具竞争力。此外,我们搭建了物理原型,采用市售随机光纤束实现光学混洗,与低成本商用传感器配合运行于GRR快门模式。实测显示,使用8位传感器(原动态范围48dB)实现了最高73dB的动态范围。
原文摘要 · Abstract (English)
High-dynamic-range (HDR) imaging is an essential technique for overcoming the dynamic range limits of image sensors. The classic method relies on multiple exposures, which slows capture time, resulting in motion artifacts when imaging dynamic scenes. Single-shot HDR imaging alleviates this issue by encoding HDR data into a single exposure, then computationally recovering it. Many established methods use strong image priors to recover improperly exposed image detail. These approaches struggle with extended highlight regions. We utilize the global reset release (GRR) shutter mode of an off-the-shelf sensor. GRR shutter mode applies a longer exposure time to rows closer to the bottom of the sensor. We use optics that relay a randomly permuted (shuffled) image onto the sensor, effectively creating spatially randomized exposures across the scene. The exposure diversity allows us to recover HDR data by solving an optimization problem with a simple total variation image prior. In simulation, we demonstrate that our method outperforms other single-shot methods when many sensor pixels are saturated (10% or more), and is competitive at a modest saturation (1%). Finally, we demonstrate a physical lab prototype that uses an off-the-shelf random fiber bundle for the optical shuffling. The fiber bundle is coupled to a low-cost commercial sensor operating in GRR shutter mode. Our prototype achieves a dynamic range of up to 73dB using an 8-bit sensor with 48dB dynamic range.
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