A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of PhilosophyThe plenoptic camera is an emerging technology in computer vision able to capture
a light field image from a single exposure which allows a computational change of
the perspective view just as the optical focus, known as refocusing. Until now there was
no general method to pinpoint object planes that have been brought to focus or stereo
baselines of perspective views posed by a plenoptic camera.
Previous research has presented simplified ray models to prove the concept of refocusing
and to enhance image and depth map qualities, but lacked promising distance
estimates and an efficient refocusing hardware implementation. In this thesis, a pair of
light rays is treated as a system of linear functions whose solution yields ray intersections
indicating distances to refocused object planes or positions of virtual cameras that project
perspective views. A refocusing image synthesis is derived from the proposed ray model
and further developed to an array of switch-controlled semi-systolic FIR convolution
filters. Their real-time performance is verified through simulation and implementation by
means of an FPGA using VHDL programming.
A series of experiments is carried out with different lenses and focus settings, where
prediction results are compared with those of a real ray simulation tool and processed
light field photographs for which a blur metric has been considered. Predictions accurately
match measurements in light field photographs and signify deviations of less than 0.35 %
in real ray simulation. A benchmark assessment of the proposed refocusing hardware
implementation suggests a computation time speed-up of 99.91 % in comparison with a
state-of-the-art technique.
It is expected that this research supports in the prototyping stage of plenoptic cameras
and microscopes as it helps specifying depth sampling planes, thus localising objects and
provides a power-efficient refocusing hardware design for full-video applications as in
broadcasting or motion picture arts
