红外成像系统热离焦建模与数学聚焦方法研究

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题名	红外成像系统热离焦建模与数学聚焦方法研究
作者	张程硕
学位类别	博士
答辩日期	2016-05-26
授予单位	中国科学院沈阳自动化研究所
导师	史泽林 ; 徐保树
关键词	红外成像系统热离焦图像复原图像质量评价无热化
其他题名	Research on thermal defocus modeling and digital refocusing for athermalization of infrared imaging systems
学位专业	模式识别与智能系统
中文摘要	本文以提高红外成像系统的环境温度稳定性为目标，开展温度变化下红外成像系统热效应建模，推导热离焦点扩散函数的数学表达，结合点扩散函数参数辨识算法和数学聚焦算法实现红外成像系统的数学无热化，降低红外成像系统的设计难度和成本。研究内容和成果包括：1、红外成像系统温变离焦建模。在几何光学与傅里叶光学理论指导下，以温度变化对红外成像系统光学参数，成像质量和点扩散函数的影响研究为三条主线，分别给出了温度-焦点漂移量计算模型，温度变化与恒温离焦对成像影响等价性论证和热离焦点扩散函数计算模型；提出了红外成像系统温变等效离焦量的概念，并给出了计算模型。针对各计算模型设计并开展了物理实验，验证了模型的正确性。该热离焦模型为数学无热化方法提供了较为完善的物理基础。2、热离焦点扩散函数参数化估计。针对热离焦红外图像复原需要估计点扩散函数的问题，提出了一种基于点扩散函数功率谱估计的离焦参数辨识算法。该算法以自然场景的清晰图像功率谱定律为理论基础，结合傅里叶切片定理估计热离焦点扩散函数的功率谱，由此计算热离焦模型参数。实验结果表明,该方法能准确地辨识出热离焦点扩散函数的模型参数，同时具有较强的抗噪性。3、红外成像系统的数学聚焦方法。数学聚焦是一个热离焦图像复原逆问题，能够转化为对变换域最优收缩映射函数的求解问题，提出了一种收缩映射函数标定的数学聚焦方法。实验表明该算法能够在保证具有较高复原信噪比的前提下，具有较快的执行速度。热离焦点扩散函数参数化估计和数学聚焦算法为数学无热化方法提供了可行的数学实现。4、数学无热化方法及其评价。以红外成像系统的热离焦模型为物理基础，结合热离焦点扩散函数参数估计和数学聚焦算法，给出数学无热化方法实现的技术途径；通过条带靶标对数学无热化红外成像系统进行客观评价。根据热离焦过程各向同性的特点，结合图像块结构度量算子，提出了一种无参考的数学聚焦图像质量评价方法，实现重聚焦结果的无参考评价。最后，分析了实际应用中大温差环境下数学无热化方法因宽光谱成像导致的使用局限。
英文摘要	From 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.
语种	中文
产权排序	1
页码	124页
内容类型	学位论文
源URL	[http://ir.sia.cn/handle/173321/19621]
专题	沈阳自动化研究所_光电信息技术研究室
推荐引用方式 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]. 中国科学院沈阳自动化研究所. 2016.