亚像元动态成像技术中系统的调制传递函数

亚像元动态成像技术是国际上目前实现遥感器小型化非常有效的新方法，因而研究亚像元动态成像系统的调制传递函数（MTF）显得非常必要和重要。本文分析亚像元动态成像系统的MTF模型，并给出亚像元动态成像系统MTF的数学表达式。     

高速TDI CCD亚像元动态成像系统分析

亚像元动态成像技术是目前实现相机小型化及提高相机空间分辨率的有效方法。将亚像元动态成像技术引入高速TDICCD相机中,通过特殊设计的光学拼接方法,使相机在不影响扫描速度及不改变TDICCD器件尺寸和相机焦距的情况下,可大大提高空间分辨率。为评价该TDICCD亚像元动态成像系统的成像质量,对成像系统的调制传递函数(MTF)进行了分析,分析结果表明该TDICCD亚像元动态成像技术可以将系统的空间分辨率提高1.6倍以上。     

扫描型亚像元成像处理对热成像系统性能改善的模拟分析

基于光学微扫描的亚像元成像技术是当前国内外迅速发展的一种高性能成像技术,它对探测器单元数较少且探测器单元尺寸较大的热成像系统更为有效。以扫描型焦平面探测器热成像系统FC和GP为研究对象,采用热成像系统性能模拟软件包CFLIR4.0,分析了光学系统的相对孔径、过采样和亚像元成像等对热成像系统性能的影响,包括传递函数MTF、噪声等效温差NETD、最小可分辨温差MRTD以及系统的探测和识别距离。模拟分析表明:过采样成像可提高热成像系统的性能,亚像元成像处理可进一步提高热成像系统的性能,可明显地提高系统的作用距离。研究结果对亚像元热成像技术的发展具有参考意义。     

亚像元成像系统细胞神经网络插值方法研究

亚像元动态成像技术是实现卫星相机小型化及提高相机空间分辨率的有效方法。采用细胞神经网络(CNN)实现了对亚像元图像的实时插值,对插值的过程进行了详细的分析,并与基于亚像元图像的传统插值方法进行了对比。结果表明,亚像元成像系统细胞神经网络插值方法不仅可以节约系统资源,而且还可以提高系统的运行速度。通过仿真证明了该方法的正确性。     

动态MTF的数值计算与分析

受振动的影响,在积分时间内,光学系统成像是一个动态过程.对于动态成像,常采用动态调制传递函数(MTF)作为评价振动对像质影响的工具.针对动态MTF,提出一种适用于任意运动形式的数值计算方法,该方法还可以扩展到计算二维运动时的动态MTF.该方法可用于预估和评价动态成像系统的成像质量,计算的结果还可用于运动模糊图像的仿真与...     

航空相机像旋动态调制传递函数分析与研究

航空相机在采用旋转扫描反射镜成像过程中存在像面旋转,会导致图像模糊,成像质量下降,必须采用像旋补偿机构进行补偿。目前,通过人眼观察图像模糊程度和电机同步控制精度评价像旋补偿精度,都不能客观准确评价系统成像质量。为建立航空相机成像质量与像旋补偿系统其他指标之间的直接关系,提出基于极坐标系的动态调制传递函数(MTF),并提出基于倾斜刃边法与模糊路径法相结合的方法测量航空相机旋转像移动态MTF。设计扇形靶标旋转动态成像实验,利用旋转动态MTF和倾斜刃边法得到图像动态MTF计算值,并基于图像模糊路径测量转台转动时图像动态MTF测量值。实验结果表明,转台以20~300(°)/s匀速转动时,空间频率在旋转动态MTF到达第一个零点频率前,动态MTF计算值和测量值曲线近似重合,验证了旋转动态MTF的正确性;空间频率在小于0.7零点频率范围内,两动态MTF曲线相对误差最大值和均值分别小于6%,2%,进而证明了测量方法的准确性。     

光纤成像光谱仪中谱线畸变对调制传递函数的影响

将光纤传像束应用到色散型成像光谱仪中取代其狭缝,链接望远系统和光谱仪组成光纤成像光谱仪。它是二重采样系统,光谱仪的谱线畸变使光纤束采样像元的像与探测器像元之间产生对准偏差,从而对第二次采样过程产生影响,导致调制传递函数(MTF)下降。从线扩散函数角度出发推导出采样过程光学传递函数,分析了谱线畸变对系统MTF的影响,建立了一套评价光纤成像光谱仪MTF的模型。该模型比狭缝型成像光谱仪MTF计算模型多了一项光纤积分MTF因子和一项由谱线畸变引起的对准偏差MTF因子,最后用该模型评价了某机载可见近红外波段光纤成像光谱仪MTF。MTF计算模型的推导和建立方法对计算二重采样系统光学传递函数有参考意义,能指导光纤成像光谱仪的设计。     

光电子技术与器件 光电成像与器件

TH7032007043630考虑填充率下亚像元与过采样成像MTF的对比=Con-trast MTF between sub-pixel arithmetic and over-samplingi maging considering filling rate[刊,中]/陈翼男(北京理工大学信息科学技术学院光电工程系.北京(100081)),金伟其…//北京理工大学学报.?2007,27(2).     

用于成像侦察的CCD探测器成像分辨力的探讨

通过对CCD探测器成像过程的模拟,分析了CCD成像在像元几何尺寸及成像灰度方面的数字离散化特征对CCD成像分辨力的影响,给出了CCD成像分辨力与CCD像元分辨力的关系,同时也给出了在相应情况下的调制度传递函数(MTF)的数值。     

航空相机动态调制传递函数分析与研究

影像位移是影响航空相机分辨率的主要因素。用MTF对动态成像质量做出评价,确立合理的稳定系统性能指标,是设计过程中常用的手段。为此研究了匀速运动,变速运动和正弦运动条件下的动态MTF,针对目前无法准确评价的低频正弦运动,提出了基于离散相位区间的动态MTF计算方法。分析结果表明,在像模糊斑大小相同的情况下,高频振动对像质的破坏最严重,直线运动次之,低频振动最轻。根据所作分析可以针对给定的影像位移计算出相应的动态MTF,为航空相机像质评价提供了准确定量的参考。     

基于B样条插值算法的亚像元技术的研究

亚像元动态成像技术是目前实现卫星相机小型化及提高相机空间分辨率的一种有效方法。在不改变TDICCD相机的焦距、成像距离,以及TDI CCD器件的像元尺寸的前提下,亚像元动态成像技术可以提高相机的空间分辨率。利用B样条插值算法,研究了TDI CCD相机的图像的亚像元动态插值问题,由两幅相机输出的原始图像经过算法得到比原图像分辨率高的图像,并对比了该算法与其它几种算法的效果,分析结果表明,该算法较其它算法得到的高分辨率图像的效果更佳。     

亚象元动态成象系统空间分辨率研究

本文从采样间隔和调制传递函数两个方面分析了亚象元成象系统的理论空间分辨率.并将其与实际结果进行了比较.     

亚像元线阵CCD推扫成像系统调制传递函数分析方法

通过对CCD器件成像过程的描述 ,分析亚像元成像系统工作方式 ,从几何参数的角度研究亚像元系统特点 ,及其调制传递函数的分析方法 ,并从理论上进行模拟计算。     

Single-shot subpixel response measurement with an aperture array pixel mask

We first point out that the subpixel response function is another kernel function in digital imaging. Then we show that the subpixel response function of CMOS imaging sensor pixels can be measured with an aperture array pixel mask in a single-shot image capture. Our technique permits high-resolution subpixel response function measurement of imaging pixels for superresolution imaging applications.     

Three-dimensional integral imaging with improved visualization using subpixel optical ray sensing

In this Letter, we propose an improved three-dimensional (3D) image reconstruction method for integral imaging. We use subpixel sensing of the optical rays of the 3D scene projected onto the image sensor. When reconstructing the 3D image, we use a calculated minimum subpixel distance for each sensor pixel instead of the average pixel value of integrated pixels from elemental images. The minimum subpixel distance is defined by measuring the distance between the center of the sensor pixel and the physical position of the imaging lens point spread function onto the sensor, which is projected from each reconstruction point for all elemental images. To show the usefulness of the proposed method, preliminary 3D imaging experiments are presented. Experimental results reveal that the proposed method may improve 3D imaging visualization because of the superior sensing and reconstruction of optical ray direction and intensity information for 3D objects.     

Robust CCD photoelectric autocollimator for outdoor use

A robust charge-coupled device(CCD) photoelectric autocollimator for outdoor use is designed and demon-strated. The influence of outdoor conditions on the signal-to-noise ratio(SNR) and imaging quality of the measuring system is experimentally analyzed. The pulse width modulation technology is applied to the automatic feedback control of the actively regulated illuminating light source of the measuring system to maximize SNR while avoiding image saturation. A Fourier phase shift method for subpixel estimation is adopted to achieve high-accuracy measurement in the presence of noises. Experimental results indicate that the technologies proposed here largely improve the measuring stability,dynamic range,and accuracy of the CCD photoelectric autocollimator used outdoors.     

A Gabor subband decomposition ICA and MRF hybrid algorithm for infrared image reconstruction from subpixel shifted sequences

An image blind reconstruction, as a blind source separation problem, has been solved recently by independent component analysis (ICA). Based on ICA theory, in this paper, a high resolution image is reconstructed from low resolution and subpixel shifted sequences captured by infrared microscan imaging system. The algorithm has the attractive feature that neither the prior knowledge of the blur kernel nor the value of subpixel misregistrations between the input channels is required. The statistical independence in the image domain is improved by the multiscale Gabor subband decompositions, which are designed for the best ability to cover the whole spatial frequency and to avoid overlapping between the subbands. The mutual information is employed to locate a subband with the least dependent components. In terms of MAP estimator, we combine the super-Gaussian with Markov random field to form a hybrid image distribution. This strategy helps to estimate the separating matrix reasonable to extract the sources with the image properties, that is, sharp enough as well as correlative in local area. The proposed algorithm is capable of performing high resolution image sources which are not strictly independent, and its viability is proved by the computer simulations and real experiments.