Studies On The High Dynamic Range Imaging System Based On Spatial Light Modulator

Image information is one of the information technology branches which include the most part of information field. In many important applications, the dynamic range of solid-state imaging sensors is critical. As a result, the extension of dynamic range of solid-state imaging sensors is one of the key methods to extract more information from imaging.This project developed a high dynamic range imaging (HDRI) system based on spatial light modulator and solid-state imaging sensors. The depth of modulation of spatial light modulator is determined by the output of solid-state imaging sensors. Hence, a negative-loop control system is constituted to extend the dynamic range of solid-state sensors. This thesis includes the following parts:(1) An overview of current technologies for the enhancement of dynamic range of solid-state imaging sensors. A new method based on LCoS spatial light modulator is developed and the experimental system is designed. The expectation of dynamic range of solid-state imaging sensors extension is 42.3db.(2) The negative-loop feedback control is analyzed and formulated. The initial conditions, stability conditions and (non-gray inversion) conditions of feedback system are determined. Robust PID controller is designed. The feasibility of direct feedback control is studied with simulation. The range of feedback depth is discovered for the convergence of output images.(3) The appearance of Moire fringes is described and analyzed. The method to eliminate Moire fringes is achieved by three methods: fast Fourier transformation (FFT), interpolation, and smooth.(4) Two contrast adjustments methods: based on adaptive CLUT table and based on adaptive LCoS driver voltage adjustment designed to improve HDRI output. (5) With the analysis of the possibility of off-line operation, according to HDRI and FPGA, off-line operation method is designed. Embedded FPGA program is developed and time sequence is analyzed.