Refocusing distance of a standard plenoptic camera CHRISTOPHER HAHNE,1,* AMAR AGGOUN,1 VLADAN VELISAVLJEVIC,1 SUSANNE FIEBIG,2 AND MATTHIAS PESCH2 1Department of Computer Science & Technology, University of Bedfordshire, Park Square, Luton, Bedfordshire, LU1 3JU, United Kingdom 2ARRI Cine Technik, Türkenstr. 89, D-80799 Munich, Germany *
[email protected] Abstract: Recent developments in computational photography enabled variation of the optical focus of a plenoptic camera after image exposure, also known as refocusing. Existing ray models in the field simplify the camera’s complexity for the purpose of image and depth map enhancement, but fail to satisfyingly predict the distance to which a photograph is refocused. By treating a pair of light rays as a system of linear functions, it will be shown in this paper that its solution yields an intersection indicating the distance to a refocused object plane. Experimental work is conducted with different lenses and focus settings while comparing distance estimates with a stack of refocused photographs for which a blur metric has been devised. Quantitative assessments over a 24 m distance range suggest that predictions deviate by less than 0.35 % in comparison to an optical design software. The proposed refocusing estimator assists in predicting object distances just as in the prototyping stage of plenoptic cameras and will be an essential feature in applications demanding high precision in synthetic focus or where depth map recovery is done by analyzing a stack of refocused photographs. © 2016 Optical Society of America OCIS codes: (080.3620) Lens system design; (110.5200) Photography; (110.3010) Image reconstruction techniques; (110.1758) Computational imaging.