CCD相机成像系统调制传递函数测量方法的研究
文献类型：学位论文
| 作者 | 官明朕
|
| 学位类别 | 硕士 |
| 答辩日期 | 2015-10 |
| 授予单位 | 中国科学院大学 |
| 导师 | 张晓辉 |
| 关键词 | 调制传递函数(MTF) 倾斜刃边法 CCD相机 |
| 其他题名 | Study on MTF Measurement of CCD Camera System |
| 学位专业 | 测试计量技术及仪器 |
| 中文摘要 | 调制传递函数(MTF)是评价光学成像系统性能的重要指标之一，它客观地反映了光学成像系统的空间频率响应特性，是衡量相机成像质量的客观标准。在光电整机成像系统可近似看作线性移不变系统的前提下，MTF仍适用于对光电成像系统性能的评价。近些年，基于图像质量分析的调制传递函数测试技术逐步发展起来，它通过采集到测试靶标所成的像，进行分析处理来获取系统的调制传递函数。因其系统结构简单、适用性强，是目前调制传递函数测试的常用方法之一。 本文对调制传递函数的基础理论和CCD相机调制传递函数测量技术进行了深入研究。提出了一种基于倾斜刃边法的改进测量方法。该方法由Canny算子检测采集到的图像中的刃边分割位置，结合刃边图像直方图呈双峰性的特点，利用类间方差最大化阈值分割算法（Otsu）计算对Canny算子性能具有决定意义的高阈值，然后以每行的质心通过位置配准确定待求ESF的中心位置，对刃边分割位置及其邻域数据进行采样，将获得的二维信息数据整体投影到一维细分采样间隔中，得到提高采样率下平均处理的数据，不仅减少了信号混叠，而且有效的抑制了刃边法容易受微分过程所带来的的随机噪声放大的影响，提高了测量结果的准确性。理论仿真下该方法最大偏差为0.0071。通过实验与在系统奈奎斯特频率处的理论值进行了比较，误差在2%以内。证明了该方法的准确性。对改进的倾斜刃边法影响测试精度的参数设置进行了仿真分析，实验验证了仿真分析的结论。 分析了斜狭缝法的原理，并使用该方法对同样的实验室CCD相机的调制传递函数进行了测量。通过与改进的倾斜刃边法的测试结果进行比较，两种方法测 试结果误差在5%以内，进一步验证了改进的斜刃边法测试的准确性。 |
| 英文摘要 | Modulation Transfer Function is an important indicator of performance evaluation of optical imaging system, which reflects the spatial frequency response characteristics of imaging system objectively, and it is a objective criteria for measuring the image quality of the camera. Photoelectric imaging system can be approximately as a linear shift invariant system on the premise that MTF is suitable for performance evaluation of the imaging system. In recent years based on the modulation transfer function of image quality analysis testing technology is through collecting the image of the test target, then processing the datas to calculate the modulation transfer function. It is one of the common methods currently of measuring the modulation transfer function because of its simple structure of system and strong practicability. In this paper, the basic theory of the modulation transfer function and measurement technology of the modulation transfer function of CCD camera were studied. An improved method is presented based on the slanted-edge method. It uses the Canny algorithm to detect edge in the acquired image, and calculate the high threshold which is significant to the Canny algorithm by using the Otsu algorithm combined with the bimodal characteristics of the edge image histogram. Then two-dimensional edge data sampled with subpixel spacing from a region along the direction of the detected edge is reprojected to a one-dimensional array of sub-pixel bins, the ESF is obtained after averaging under improving the sampling rate. It increases the signal-to-noise ratio of the measurement. It not only reduces the signal aliasing, but also suppressed the impact of noise amplification brought from differential process in the edge method more effectively. The maximum deviation from the theoretical simulation is 0.0071. The experimental value is compared with theoretical value of the system at the Nyquist frequency, the error is within 2%. The experiment has proved the accuracy of this method. We use this method to test the MTF of CCD camera in the laboratory, and analyze the influences of parameter settings including different contrast of images and different angles of edge images on accuracy of the MTF measurement. The experiment has proved the conclusion from simulation. We analysis the principle of the oblique slit method, and use this method to calculate the modulation transfer function of the same CCD camera in the laboratory. Compared with the results calculated by the improved slanted edge method, the error is within 5%, which further validates the accuracy of the improved slanted edge method. |
| 语种 | 中文 |
| 公开日期 | 2016-05-03 |
| 源URL | [http://ir.ciomp.ac.cn/handle/181722/49281]  |
| 专题 | 长春光学精密机械与物理研究所_中科院长春光机所知识产出 |
| 推荐引用方式 GB/T 7714 | 官明朕. CCD相机成像系统调制传递函数测量方法的研究[D]. 中国科学院大学. 2015. |
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