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Alternative TitleResearch on thermal defocus modeling and digital refocusing for athermalization of infrared imaging systems
Thesis Advisor史泽林 ; 徐保树
Keyword红外成像系统 热离焦 图像复原 图像质量评价 无热化
Call NumberTN215/Z31/2016
Degree Discipline模式识别与智能系统
Degree Name博士
Degree Grantor中国科学院沈阳自动化研究所
Place of Conferral沈阳
Other AbstractFrom the constrained problem in improve the stability of infrared imaging systems under thermal environment, this paper carries out the study of thermal defocus model and digital refocus method. The final aim is to establish a new athermalization for infrared systems, called digital athermalization by modeling the PSF of thermal defocus, estimating the PSF from defocus image and refocusing blurry image. The digital athermalization can reduce the difficulty and cost of the design for infrared optical imaging systems. The study includes the following four parts: 1. Thermal defocus model of infrared imaging system. Though the guide of the geometry optical and Fourier optical theory, with the three basic studies of thermal effect: the optical parameter of infrared imaging system, imaging quality and the PSF, focal shift model, the equivalence between thermal effect and defocus, and the PSF of thermal defocus are proposed respectively. Equivalent thermal defocus amount and its calculating model are proposed to describe the equivalence. The experiments for vertify the proposed models are designed by an assembly of 5-dimension translation stages. The thermal defocus model of infrared imaging system establishes the physical foundation for digital athermalization. 2. PSF estimation method from defocus image. For the image restoration require of PSF, a PSF estimation method based on spectral irregularities is proposed. By the model of defocus influence and the Fourier slice theorem, the power spectrum of the PSF is estimated from the Radon transform of defocus image with the power-law. The optimization equation with defocus parameters is established by minimizing the error between power spectrums from the defocus model and estimation. Defocus parameters can be obtained by using gradient descent method. Experimental results show that the method can accurately identify the parameter of all defocus models with good anti-noise capacity. 3. Digital refocus methed for infrared imaging system. Digital refocus is the inverse problem of themal defocus. Rather than directly modeling the prior of the sharp image to obtain the shrinkage functions, we calibrate them for restoration directly by using the acquirable sharp and blurry image pairs from the same infrared imaging system. Therefore, a fast approach to digital refocus of infrared defocus image based on shrinkage functions calibration is proposed. We demonstrate the effectiveness of our approach by testing its quantitative performance from simulation experiments and its qualitative performance from a real infrared imaging system. PSF estimation method and digital refocus methed establish the mathematical achievement for digital athermalization. 4. Digital athermalization and its quality assessment. Based on the model of infrared imaging system, combined with PSF estimation method and digital refocus methed, the digital athermalization is proposed finally. A bar target imaging test is used for objective assessment of digital athermalization. According to the characteristic of defocusing process, a no-reference quality assessment of refocus image is proposed. Finally, the limition of digital athermalization due to wide spectral imaging is analyzed.
Contribution Rank1
Document Type学位论文
Recommended Citation
GB/T 7714
张程硕. 红外成像系统热离焦建模与数学聚焦方法研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2016.
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红外成像系统热离焦建模与数学聚焦方法研究(7572KB)学位论文 开放获取CC BY-NC-SAApplication Full Text
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