A Method For Quality Enhancement Of Low-luminous Imaging Based On Simple Lens System

Optical imaging design has always been a trade-off between imaging quality and manufacturing price and volume.In order to improve the imaging quality of the optical system,the aberrations are generally eliminated by increasing the number of optical elements to form a lens group containing several lenses,or by making an aspherical lens or even a free-form lens to improve the imaging quality.With the development of computational photography technology in recent years,combined with digital sensing technology,image processing technology,etc.,there has been a lightweight and affordable simple lens system instead of heavy and expensive combination lens of SLR camera system.The simple lens contains only a few convex lenses,and the image quality will inevitably decrease,especially when the shooting condition is poor,such as low illumination,the information contained in the image will lose a lot.The aim of this paper is to propose a technique for improving the image quality of simple lens under low light condition.The blur kernel calibration method is used to replace the kernel estimation by blind deconvolution.At the same time,the contour information of the image is recovered and the image quality is improved.The main research content and work can be summarized as the following aspects:1.The reduction reason of the simple lens imaging quality is analyzed,then the problem is transformed into the deblurring problem and establish the mathematical model.Accurate estimation of blur kernel is the key to image restoration.We analyze the lack of existing kernel distribution model and propose the more suitable NSAS(Normal Sinh-Arcsinh)model.2.The design of the process frame work can accurately estimate the blur kernel of the simple lens under the low light condition.The estimation of non-parametric blur kernel includes the design of the calibration image,the image mapping and the calibration of image pair,the iterative solution of the non-parametric blur kernel.Then the non-parametric blur kernel is substituted into the NSAS model to solve the parameter blur kernel by using the Powell algorithm.3.Under low light condition,most of the details of the image are lost.In the calibration process does not just estimate the blur kernel of the image,and get its tone curve.It is proposed to use the tone curve to correct the original blur image to restore some of the image contour,the overall quality of the image is improved by deblurring.4.Aiming at the blur characteristics of the image,this paper proposes a method that restores the clear image based on the dark channel priori and non-blind deconvolution.In addition,the ADMM algorithm is used to improve the operation speed and shorten the computation time in the iterative process.The simple lens system has important research value and broad application prospect because of its small weight and low price.However,due to its structural characteristics,the image is suffered from chromatic aberration and other factors.If it is in poor shooting conditions under the low light conditions,the image quality will be more degraded.The method proposed in this paper can obviously improve the image quality of the simple lens under the condition of insufficient illumination.However,it is necessary to form the final mature application technology,and it needs more innovative and detailed and detailed work.