Study On Fourier Single-Pixel Imaging Quality

As a novel imaging technique,Fourier single-pixel imaging uses a single-pixel detector and the phase shift method to obtain the Fourier spectrum of the image and the inverse Fourier transform to reconstruct the image of the object,which has potential applications in many fields such as 3D imaging.In order to promote the application of Fourier single-pixel imaging,it is necessary to study how to improve the quality of Fourier single-pixel imaging.Hence in this thesis,we study the influence of the defocused light source,ambient light and the intensity of reflected light et.al.on the image quality of Fourier single-pixel imaging,respectively.Meanwhile,an image quality optimization strategy is explored and implemented.Based on defocusing model and image restoration,the influence of the defocused light source on the image quality of Fourier single-pixel imaging and its optimization is investigated both theoretically and experimentally.On the one hand,we introduce Gaussian model to describe the defocusing and analyze theoretically Fourier single-pixel imaging with defocused light source.On the other hand,we employ digital light projector modulated by Fourier basis pattern as the light source.We investigate the influence of the defocusing of the light source on the peak signal-to-noise ratio(PSNR)of Fourier single-pixel imaging by changing the defocusing parameter of the light source.The results show that the more the light deviates from the focus of light field,the worse the imaging quality.Specifically,the peak signal-to-noise ratio of the reconstructed image decreases from 28.4 d B to 20.5d B.Furthermore,we explore an adaptive strategy to optimize the defocused reconstructed image which combines with the strategy of adaptive filter and blind deconvolution.The mask size of the optimization algorithm can be adaptively selected according to the peak signal-to-noise ratio of the reconstructed image.The peak signal-to-noise ratio of the image after optimization improved by 1.4 d B-4.0 d B.It is helpful to the application of Fourier single-pixel imaging in complex environments.Based on four-step phase shift method,the disturbance of the ambient light on the image quality of Fourier single-pixel imaging is investigated both theoretically and experimentally.The disturbance of three types of ambient light on Fourier single pixel imaging is analyzed in detail.The theoretical and experimental results show that:(1)The DC ambient light(the fringe of ambient light in the spatial frequency domain remains unchanged)has no effect on the image quality of Fourier single-pixel imaging;(2)The frequency and phase of the modulated ambient fringe are the same as the Fourier basis pattern has no effect on the image quality of Fourier single-pixel imaging;(3)The frequency or phase of the modulated ambient fringe is different from the Fourier basis pattern has effect on obtaining the whole Fourier spectrum of the image of the object,resulting in poor image quality of Fourier single-pixel imaging.It is helpful to the application of Fourier single-pixel imaging in outdoor environments.In the traditional imaging,the low reflected light intensity of the object may result in poor imaging quality.Accordingly,the influence of intensity decrease of reflected light on the image quality of Fourier single-pixel imaging is investigated experimentally by rotating the polarized angle of the two polarizers.The results show that the quality of reconstructed image decreases with the decrease of reflected light intensity,when the intensity of reflected light is lower than the detection threshold,the reconstructed image cannot be recognized normally.It is helpful to the application of Fourier single-pixel imaging in long-distance imaging.