非制冷红外图像非均匀性校正在FPGA上的实现

红外焦平面阵列（IRFPA）的非均匀性是影响红外系统成像质量的关键性因素,在此提出了一种非制冷红外图像的非均匀性校正及其在FPGA上的实现方法,通过对非制冷红外图像盲元及非均匀校正方法分析,提出了二点加一点定标校正方法,并利用FPGA实现红外图像非均匀校正的实时处理,获得了较好的实验结果。利用二点加一点定标校正方法,可以改善红外图像非均匀性校正效果,用在FPGA上实现非均匀性校正可以实现红外图像的实时处理,便于集成和移植。     

可见近红外、短波红外超光谱成像仪在轨数据处理技术研究

分析了天基可见近红外、短波红外超光谱成像仪的数据特征,提出了一种用于可见近红外、短波红外超光谱成像仪的在轨数据处理系统.重点介绍了星上定标及非均匀性校正、星上数据压缩等算法.超光谱成像仪在地面定标的基础上进行星上辐射和光谱定标,用基于定标和基于场景两种方法对图像数据做非均匀性校正.星上数据去噪及压缩采用基于小波变换的方法,去噪后的数据用3D-Tarp算法压缩.该系统设计既考虑了算法的有效性,又考虑了恶劣的星上环境对时间、功耗等指标的限制,在尽量少损失信息的情况下,能有效去除噪声,提高信噪比,减少星上存储和下传的数据,提高图像质量.     

基于全卷积网络的红外图像非均匀性校正算法

针对红外成像系统在经过两点校正后,随时间漂移仍然会出现的非均匀性噪声,提出一种基于全卷积深度学习网络的红外图像非均匀性校正算法,使用子网络与主网络相结合的方式进行非均匀性校正.该算法设计了非均匀性等级估计子网络,将含有非均匀性噪声的红外图像输入子网络后,输出非均匀性等级估计图,并和待校正红外图像一并输入校正主网络.子网...     

基于TLS的正交小波变换红外图像去噪

提出了一种基于总体最小二乘的正交小波变换红外图像去噪算法。对红外图像进行离散正交小波变换,分别对各个分解层的高频子带,通过总体最小二乘算法估计小波系数,获得各个高频子带信号的估计系数,然后通过正交小波反变换得到去噪图像。仿真结果表明,该红外图像去噪算法能有效去除加性红外图像噪声,在信噪比、直方图匹配等方面都有较大改善,并获得了良好的主观视觉效果。     

傅里叶变换红外成像光谱仪非均匀性在线定标与校正研究

由于傅里叶变换红外成像光谱仪结构的特殊性,其非均匀性在线定标与校正在工程上一直没有得到有效解决。首先对IRFPA非均匀性校正的原理与算法进行了简要阐述,在此基础上,通过对时间调制型、空间调制型及时间空间联合调制型傅里叶变换红外成像光谱仪原理结构的深入分析,针对这三种制式的光谱仪,分别研究出了相应的非均匀性在线定标与校正的方法,为星载傅里叶变换红外成像光谱仪非均匀性的在轨定标奠定了良好的技术基础。     

红外焦平面阵列非均匀性校正精度的研究

定标校正法是目前人们实际使用较多的一种红外焦平面阵列非均匀性校正方法。该方法采用的算法简单,易于用硬件实时实现,但也存在校正精度低的缺点,针对这一不足,首先通过实验得到了红外焦平面探测器的实际非线性响应曲线,然后在此基础上进一步分析了定标点的数量及选取对红外焦平面阵列非均匀性校正精度的影响,为提高定标校正法的校正精度提供了依据。     

基于生成对抗网络的红外图像自适应校正算法

红外相机经过两点校正后会发生漂移,导致图像产生非均匀性噪声.传统的基于场景的非均匀性校正算法适应性较强,但会产生鬼影问题.基于深度学习的非均匀性校正方法,面对红外图像特殊的非均匀性噪声,随着网络深度增加,很容易出现图像模糊,对比度变小,细节丢失问题.针对此问题,提出一种基于生成对抗网络的非均匀性校正算法,网络分为生成网...     

星载红外成像系统IRFPA非均匀性在轨定标与实时校正

针对星载红外成像系统在轨定标等特殊环境条件的应用要求,研制了一种基于现场可编程门阵列(Field-Programmable Gate Array,FPGA)的红外焦平面阵列(Infrared Focal Plane Array,IRFPA)非均匀性在线定标与实时校正芯片系统.由于对输入信号进行了标准化设计,该系统可用于各类红外成像系统的IRFPA非均匀性在线定标与实时校正处理.这种系统在时钟信号的驱动下以流水线方式运行,在对非均匀红外图像进行实时校正的同时,能够在线获取定标图像并能对存储器中的校正系数进行在线更新.该系统具有体积小、运算速度快、稳定可靠以及易于升级等优点,为星载红外成像系统IRFPA非均匀性的在轨定标开辟了一条有效的技术途径.     

提高红外图像均匀性的两级校正技术研究

凝视红外焦平面成像系统中经常需要根据目标红外辐射强度来修改探测器积分时间,当积分时间变化后,红外图像的均匀性明显变差.探索了一种利用积分时间校正与目前实用性较好的两点温度定标法相结合的焦平面非均匀性校正方案,不仅使红外图像的均匀性得到较大幅度提高,而且在修改积分时间的情况下图像均匀性不受影响.     

基于改进伽马曲线的星载长波红外焦平面非均匀性校正算法

随着长波红外探测器技术的进步,通过选用宇航级大阵列长波红外探测器,天基红外遥感卫星技术得到快速发展。长波红外探器响应强非线性导致传统的基于线性模型的非均匀性校正算法校正误差大,从而影响卫星在轨使用效能。针对该问题,结合大量实验室数据和卫星在轨数据的统计分析结果,建立了一种新的长波红外探测器非线性响应模型,据此提出了一种基于改进伽马曲线的非均匀性校正算法,以有效克服探测器响应强非线性对校正精度的影响。该算法首先建立基于改进伽马曲线的探测器非线性响应模型,依据此模型对获取图像进行非线性压缩映射,实现探测器响应的线性化,然后利用星载基于定标技术的线性化算法实施非均匀性校正,同时,定标温度点根据所建立模型参数动态更新,最后通过逆非线性化压缩映射还原出实际的非均匀校正后的图像。基于人造黑体和在轨实景红外图像的实验结果表明,该算法有效解决了探测器响应强非线性对校正精度的影响,校正后图像的视觉效果和定量化指标均优于传统的星载非均匀校正算法。     

多点标定的自适应非均匀性校正方法

为了实现对红外焦平面阵列(IRFPA)获取图像的实时高精度非均匀校正,提出了一种基于多点标定的自适应非均匀性校正算法,该算法假定在环境温度变化时,校正后输出图像数据的差值与已标定的数据存在线性关系,对其进行分块并配对,采用最小二乘法,以平方和最小为准则,自适应修正校正系数,以达到实时调整非均匀校正的校正系数,对环境温度变化引起的非均匀性进行补偿的目的.实验结果表明,该方法既提高了非均匀性校正的精度又能满足实时性要求,可广泛应用于光电火控、红外成像制导等对实时性和成像质量均有较高要求的应用场合.     

Probabilistic crisscross error correction

The crisscross error model in data arrays is considered, where the corrupted symbols are confined to a prescribed number of rows or columns (or both). Under the additional assumption that the corrupted entries are uniformly distributed over the channel alphabet, and by allowing a small decoding error probability, a coding scheme is presented where the redundancy can get close to one half the redundancy required in minimum-distance decoding of crisscross errors     

Blind inverse gamma correction

The luminance nonlinearity introduced by many imaging devices can often be described by a simple point-wise operation (gamma correction). This paper presents a technique for blindly estimating the amount of gamma correction in the absence of any calibration information or knowledge of the imaging device. The basic approach exploits the fact that gamma correction introduces specific higher-order correlations in the frequency domain. These correlations can be detected using tools from polyspectral analysis. The amount of gamma correction is then estimated by minimizing these correlations.     

Atmospheric correction of ASTER

An atmospheric correction algorithm for operational use for the high-spatial resolution, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is presented. The correction is a straightforward approach relying on inputs from other satellite sensors to determine the atmospheric characteristics of the scene to be corrected. Methods for the solar reflective and thermal infrared (TIR) are presented separately. The solar-reflective approach uses a lookup table (LUT) based on output from a Gauss-Seidel iteration radiative transfer code. A method to handle adjacency effects is included that relies on model output, assuming a checkerboard surface. An example of a numerical simulation shows that the effect of a land surface on the radiance over the ocean is stronger just off the coastal zone and decreases exponentially with increasing distance from the land. A typical numerical simulation is performed over the Tsukuba lake area in Japan. The TIR approach relies on the radiative transfer code Moderate Resolution Atmospheric Radiance and Transmittance Model (MODTRAN). The code is run for a given set of atmospheric conditions for multiple locations in the scene for several representative elevations. Pixel-by-pixel radiances are then found using spatial interpolation. Sensitivity analysis of the methods indicate that the results of the atmospheric correction will be limited by the accuracies of the input parameters     

MR susceptibility misregistration correction

The authors present a new in vivo method to correct the nonlinear, object-shape-dependent and material-dependent spatial distortion in magnetic resonance (MR) images caused by magnetic susceptibility variations. This distortion across the air/tissue interface before and after the correction is quantified using a phantom. The results are compared to the distortion-free computed tomography (CT) images of the same phantom by fusing CT and MR images using fiducials, with a registration accuracy of better than a millimeter. The distortion at the bone/tissue boundary is negligible compared to the typical MRI (MR imaging) resolution of 1 mm, while that at the air/tissue boundary creates displacements of about 2 mm (for G(x) 3.13 mT/m). This is a significant value if MRI is to provide highly accurate geometric measurements, as in the case of target localization for stereotaxic surgery. The correction scheme provides MR images with accuracy similar to that of CT: 1 mm. A new method to estimate the magnetic susceptibility of materials from MR images is presented. The magnetic susceptibility of cortical bone is measured using a SQUID magnetometer, and is found to be -8.86 ppm (with respect to air), which is quite similar to that of tissue (-9 ppm).     

辐射特性测量大气传输修正研究:大气传输修正系统

大气传输修正是目标辐射特性测量的一个重要环节。介绍了研制的目标辐射特性测量大气传输修正系统和中分辨率通用辐射大气传输计算软件（CART）,展示了大气传输修正结果和外场实际水平距离测量结果的部分对比,定量评估了目标探测常用的中波和长波红外波段大气传输修正精度。     

基于响应率修正的傅里叶变换光谱仪非线性校正算法研究

傅里叶变换高光谱仪器在定量化遥感领域展现出极大的优势,非线性校正是保证在轨辐射定标精度不可缺少的过程。针对搭载于风云四号静止轨道干涉式红外探测仪（FY-4/GIIRS）运行轨道受日晒分布不均匀、仪器环境温度日变化剧烈的特点,推导出一种基于仪器光谱响应率修正的非线性校正算法,通过测量一组标准参考辐射源光谱量化值和光谱响应率,拟合得到光谱响应率一次项修正系数。在仪器环境温度变化后,利用一次项修正系数、黑体观测光谱值和黑体观测光谱响应率重新计算光谱响应率常数项修正系数,就可以得到任意仪器环境温度下的仪器非线性校正系数。经仪器发射前地面热真空（TVAC）定标试验数据验证,该算法简单有效,在各试验环境温度工况下,对180～320 K观测范围内的辐射定标精度均有明显的提高。     

激光陀螺的频率修正

本文分析了光陀螺中由于有限光束宽度对拍频频率的修正因子。证明了任意正多边形光陀螺都具有同一形式的修正因子。也计算了圆形波导传输的光陀螺中的频率修正因子,并与Zubairy等人推导的结果作了比较。     

Coding-oriented multi-view video color correction

Color inconsistency between views is an important problem to be solved in multi-view video applications, such as free viewpoint television and other three-dimensional video systems. In this paper, by combining with multi-view video coding, a coding-oriented multi-view video color correction method is proposed. We first separate foreground and background in first Group Of Pictures （GOP） by using SKIP coding mode. Then by transferring means and standard deviations in backgrounds, color correction is performed for each frame in GOP, and multi-view video coding is performed and used to renew the backgrounds. Experimental results ances in color correction and multi-view video show the proposed method can obtain better performcoding.