Unbounded High Dynamic Range Photography （摄影的高动态范围）.pdf

Unbounded High Dynamic Range Photography using a Modulo Camera Hang Zhao1 Boxin Shi1,3 Christy Fernandez-Cull2 Sai-Kit Yeung3 Ramesh Raskar1 1MIT Media Lab 2MIT Lincoln Lab 3Singapore University of Technology and Design hangzhao, shiboxin, raskar@, christy.cull@, saikit@.sg Abstract This paper presents a novel framework to extend the dy- namic range of images called Unbounded High Dynamic Range (UHDR) photography with a modulo camera. A modulo camera could theoretically take unbounded radi- ance levels by keeping only the least significant bits. We show that with limited bit depth, very high radiance lev- els can be recovered from a single modulus image with our (a) Image from intensity camera newly proposed unwrapping algorithm for natural images. We can also obtain an HDR image with details equally well preserved for all radiance levels by merging the least num- ber of modulus images. Synthetic experiment and experi- ment with a real modulo camera show the effectiveness of the proposed approach. (b) Image from modulo camera (c) Recovered image from modulo camera 1. Introduction Figure 1. A modulo camera could well recover over-exposed re- Real world scene radiance levels cover a huge dynamic gions: (a) an image taken by an 8-bit intensity camera, which has range that is impossible to completely capture given limited large areas saturated due to the bright sky; (b) an image taken by an quantization bits and well capacity on a traditional imag- 8-bit modulo camera, with the same exposure level as