A Design Method of Transmissive Digital Imaging System

Abstract

The present invention discloses a transmission-type digital imaging system design method. A transmission-type digital imaging system is composed of an optical imaging system and a digital processing system. Aberration which is not easy to compensate through digital processing is left to be corrected through optical design while aberration which is easy to compensate through digital processing is corrected through an image processing algorithms, such that optical design does not need to correct all the aberration, and, that is, a digital processing system is used for replacing parts of lenses to correct the aberration, thereby reducing the amount of lenses of a transmission-type optical lens and lowering complexity of the whole system. The method comprises establishing an optical imaging system model to acquire an optical imaging transfer function, establishing a digital processing system model to acquire a digital processing transfer function, establishing an imaging target prior model to restrain digital processing, and establishing an optimizing index function model to link the digital processing transfer function and the optical imaging transfer function to acquire a aberration-corrected digital image.

Description

technical field [0001] The invention relates to a design method of a transmission digital imaging system. Background technique [0002] With the rapid development of electronic technology and material technology, the transmission imaging system has developed from silver halide film imaging to digital imaging. Now the traditional digital imaging system is mainly composed of transmission optical system and detector system, such as figure 1 As shown, the target forms a digital image on the CCD or COMS detector through the transmission optical system imaging, and then people use the image processing algorithm to correct the digital image more or less according to the application requirements, and the digital image processing is very important for the traditional digital imaging. System (especially for daily consumer cameras, such as card cameras, single-lens reflex cameras) is not a necessary component, especially in today's digital image processing hardware and software technol...

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Problems solved by technology

[0002] With the rapid development of electronic technology and material technology, the transmission imaging system has developed from silver halide film imaging to digital imaging. Now the traditional digital imaging system is mainly composed of transmission optical system and detector system, such as figure 1 As shown, the target forms a digital image on the CCD or COMS detector through the transmission optical system imaging, and then people use the image processing algorithm to correct the digital image more or less according to the application requirements, and the digital image processing is very important for the traditional digital imaging. System (especially for daily consumer cameras, such as card cameras, single-lens reflex cameras) is not a necessary component, especially in today's digital image processing hardware and software technology with each passing day, if the digital processing is not fully used Technology, in a certain sense, has lost the characteristics of the so-called "digital" imaging, and has not fully exploited all the advantages of digital imaging

[0003] In the traditional design method of transmission digital imaging system, optical system design selects optical components to balance aberrations (defocus, distortion, astigmatism, coma, field curvature, spherical aberration, chromatic aberration) through ray tracing theory. The number of secondary aberrations is large, far more than the number of structural parameters of the optical system, and is limited by the processing and adjustment process and the type of glass material, so that each aberration will have a certain amount of residue, which will affect the clarity of the imaging result. Digital Processing is only a non-essential part of imaging effect correction. Even if imaging results need to be enhanced, the optical design does not consider the design requirements of digital processing; when designing digital processing algorithms, we only start from digital image byte information and use The signal processing theory enhances the definition of the image so that the image meets the application requirements as much as possible, and does not consider the influence of the design parameters of the optical system on the algorithm design

[0004] The traditional design method makes the quality of the optical system design the only link that determines the imaging quality, resulting in a very complicated structure of the optical system

In order to "perfectly" correct aberrations, the optical system usually requires a complex composition of ten to thirty lenses, which also makes the imaging system large in size and weight, long in development cycle, and high in cost

For example, the SLR lens we use every day is usually composed of 10-20 lenses, and the focal point of each lens must be on a straight line, otherwise the imaging will be "missing by a tiny bit", which greatly improves the process of lens processing and assembly. Difficulty, and the more the number of lenses, the lower the utilization rate of light energy

In addition, although the digital processing method of sharpening to improve contrast and smoothing to improve the signal-to-noise ratio can be used to improve the image clarity, the improvement of the signal-to-noise ratio and the improvement of the contrast are mutually restricted, and it is difficult to take care of each other. Adding the average will inevitably reduce the contrast, and the introduction of convolution algorithm for image sharpening will inevitably amplify the noise or introduce new noise

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