Geometry parameter calibration for focused plenoptic cameras

Due to the subtle structure, the exact geometry parameters of the focused plenoptic camera cannot be retrieved after packaging, which leads to inaccurate light field processing such as visible artifacts in the rendering images. This paper proposes a novel blind calibration method to calculate the geometry parameters for the focused plenoptic cameras with high precision. It translates the problem of deriving the value of the geometry parameters to be the problem of deriving the pixel patch-size of each micro-image used in subaperture image rendering based on the geometry projection of the relay imaging process in the focused plenoptic camera. Then, a dark image calibration algorithm is proposed to retrieve the position and the geometry parameters of the MLA for subaperture image rendering. A triple-level calibration board with random texture is designed to realize focus plane confirming blindly, to facilitate capturing light field images at different object distances via a single shot and to benefit intensity feature matching in determining the rendering patch size. The rendering patch-size is found by the proposed Gradient-SSIM-based fractional-pixel matching based on the geometry projection analysis. Experiments conducted on the simulated data and the real imaging system demonstrate that the proposed method can acquire the geometry parameters with high accuracy and is robust to different focused plenoptic cameras.