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【期刊论文】Interline Image Revision Method for Electrical Image Stabilization
徐之海, Li Qi*, Xu Zhihai, Feng Huajun
Proc. of SPIE Vol. 5633,-0001,():
-1年11月30日
In avigation, navigation and other fields, electrical image stabilization technique (EIS) is applied widely. Recent research for electrical image stabilization is focused on motion vector estimation, which influences accuracy of image stabilization and its applicable scope directly, and pay less attention to the relation between image stabilization algorithm and structure character of image sensor. In fact, while image sensors are interline transfer CCD, 2D rigid motion model is not accurate enough for the image stabilization algorithm. There exist the displacement between the rows in a frame, for the different rows are exposed at different time. In order to compensate the interline displacement caused by the movement of the sensor both in horizontal and vertical direction, an image revision method based on correlation was put forward for the structure character of interline transfer CCD. During exposure of each frame, the motion of camera is along uniform direction and approximately even (otherwise it is beyond application scope of EIS), so it is feasible to revise image according to the displacement at the top and the bottom of image. Image sequence was acquired by telescope with function of optical image stabilization, and then was processed by electrical image stabilization algorithm. Experiment results showed that the image fidelity has been improved remarkably after image revision processing.
Image revision,, Electrical image stabilization,, Interline transfer CCD,, Rigid motion model,, Pechan prism system
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徐之海, 何烽, 冯华君
光电工程,2004,31(6):66~69,-0001,():
-1年11月30日
CCD/CMOS图像传感器的饱和电流和背景噪音使得一次曝光很难超过60-80dB的动态范围。用LIP(Logarithmic image processing)模式将图像转换为灰色调函数,再将基于LIP模式的非线性多重微区域图像分解算法进行改进,可以适应不同亮度的单幅图像处理,提高了可分辨信息量和图像对比度,同时抑止了噪声。质量评价显示,该算法能将MOS 等级四的源图像提高到等级一。
对数图像处理, 图像分解, 动态范围, 数字图像
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徐之海, 李奇, 徐之海.冯华君, 王凌, 戴顺林
光学学报,2004,24(3):428~430,-0001,():
-1年11月30日
提出一种数学模型描述成像系统的稳定程度。通过分析证明:当目标物体为黑白分辨率标板(只有两种亮度且为周期性结构)时,成像系统的不稳定对成像结果的影响是使图像的像素灰度值按照二项分布的规律分布,因此可以用统计参量来反映成像系统的运动速率,进而表征图像的不稳定度。为了研究在不同时刻图像稳定性的变化规律,引入了统计学中表征数据离散程度的参量“标准偏差”作为描述因子。通过实验,直观地描述了一个佩肯棱镜系统的稳像过程,得出了变化曲线。曲线的波动与所观察到的图像稳定度的变化相符,证明了本描述方法是合理且有效的
成像光学, 图像稳定性, 描述方法, 佩肯棱镜系统
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徐之海, 裴锡宇, 冯华君, 李奇
光电工程,2003,30(5):63~65,-0001,():
-1年11月30日
通过计算2幅不同离焦位置的图像频谱的径向分布,推算出目标物体的离焦深度,从而调整镜头位置完成自动对焦。算法适用于任意目标物体,尽管是基于频谱的,但是并不需要计算离焦图像的频谱,算法精度可达4%,鲁棒性良好。
图像处理, 频谱分析, 自动对焦, 离焦深度法
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【期刊论文】Light energy matching method in high-resolution image reconstruction
徐之海, Ling Wang, Zhihai Xu, Huajun Feng, and Ping Zhang
May 20, 2003 Vol. 1, No.5 CHINESE OPTICS LETTERS,-0001,():
-1年11月30日
Many approaches for high-resolution image reconstruction have been proposed in some literatures. One of the most commonly ways is to reconstruct a high-resolution image from a number of rotated and translated images with low resolution. In this process, the exposure difference among original images will decrease the quality of the reconstructed image. In order to remove the influence of the exposure difference, a light energy matching method is proposed in this paper. The theoretical analysis is illustrated in details. Experimental results show that the theoretical analysis is correct and the proposed method is valid.
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