基于多通道窄带滤光片和彩色图像传感器的实时多光谱成像系统

针对复染情况的出现,采用多通道窄带滤光片与彩色图像传感器相结合的方式,设计了一种多光谱成像方法.使用多通道窄带滤光片对光源进行分光,采用多元线性回归方法建立多光谱剥离模型,并对彩色图像传感器输出的多个单色光混叠响应进行剥离,通过FPGA实现多光谱图像的实时剥离运算和输出.实验结果表明:多通道窄带滤光片的半高宽为12nm/15nm/20nm,其透射光是三个不同波段的窄带单色光;在检验水平为0.01情况下的模型具有较高的准确性;具有相同光谱特征的物质在同一波段的灰度图像上特征一致,同一物质在不同波段上的灰度图像特性差异较大.     

滤光轮分光的近红外彩色成像系统

研制了滤光轮分光的近红外彩色成像系统。针对一款光谱响应延伸至近红外波段的CMOS大面阵黑白摄像机,设计加工了大小适合的滤光轮和与光谱匹配的滤光片。根据滤光轮载荷选择了微型电机,并采用由时间同步装置产生的脉冲信号触发滤光轮的转停;采用基于灰度世界理论的RGB融合算法形成彩色图像。室内外的成像实验表明:该系统实现了近红外波段的彩色成像,尤其是夜天光中的近红外辐射,使夜间拍摄的图像亮度得到了明显的提升。     

双通偏振干涉滤光片的研究

研究了等厚度双通偏振干涉滤光片，在此基础上提出了新型双通偏振干涉滤光片，并分析了单通、双通以及新型双通偏振干涉滤光片的光谱特性。结果表明，新型双通偏振干涉滤光片不仅具有更好的光谱特性，而且能进一步减少延迟片数目，具有非常重要的实用价值，可望在基于硅片的液晶投影仪分/合色系统中得到广泛应用。     

基于四波段图像融合的彩色夜视方法研究

为了在低照度条件下获取目标的彩色图像,提高夜间对目标的识别能力,提出了基于四波段图像融合的彩色夜视方法.采用F-P滤光片设计出了透射中心在三基色光中心波长及近红外波段的四波段滤光片,在各个透射区域的平均透射率均达90%以上;将四波段滤光片设计成圆形滤色轮结构,用分光计测得了各波段滤光片的光谱透射性;对加入滤光片后的系统信噪比进行了分析和计算,分析结果表明加入滤光片不会引入噪声,计算结果表明加入蓝色、绿色、红色和近红外波段滤光片的成像系统的信噪比分别是原来单色微光夜视系统信噪比的19.59%、38.45%、47.28%和46.70%.借助国产超二代像增强器在微光实验室进行了四波段图像采集及彩色图像融合实验,实验时光照度分别为1×10~(-3)lx和1×10~(-1)lx,对获取的图像质量进行了评价.结果表明:在照度为1×10~(-3)lx时,融合的彩色图像在均值、方差和熵这三项指标上均优于过滤后的蓝色和绿色的单色图像,且由于彩色图像中利用了近红外图像进行增强,使得彩色图像亮度更高,颜色分辨性更好;在照度为1×10~(-1)lx时,融合后的彩色图像的信息熵比红、绿、蓝三种基色图像的大,彩色图像携带的信息量更大.本文的研究对彩色夜视成像系统的设计和研发具有借鉴和指导意义.     

Image composition optimization based on feature match and detail preserved

Poisson composition and gradient domain are typical and traditional composition technologies. Their main function is to create a seamless composited image. However, when the original image and the target image have quite a few differences with regard to their features (color, sharpness, noise, texture and so on), the composited image is unrealistic. We use some innovative methods to deal with the problem and there are three main stages considered in the paper. The first stage is to deal with the original image's color ahead of schedule. This is to make the original image as similar as the target image and it contributes to get a realistic composited image. The second stage is to achieve the image's multi-scale composition with wavelet pyramid. The third stage is that we use BLF filter and an image pyramid to preserve the composited image's detail after the image composition. Image composition's optimization is based on the three stages.     

雾天降质图像的快速复原

针对在雨雾霾天气条件下,大气介质的散射和吸收作用导致光电成像系统接收的图像对比度降低,细节模糊不清及颜色偏移,提出通过快速图像复原来解决此类图像退化问题。基于大气成像光学模型,在暗通道先验的理论基础上,提出了一种基于形态学滤波器的快速估算暗通道图像的方法,并采用参数自适应调整方法来抑制暗通道先验不满足时的大片天空/白墙区域的颜色失真现象。实验结果表明,该算法能够有效快速复原雨雾天气条件下的降质图像,对于600×400大小的图像,其Matlab复原仿真时间仅为0.4 s,复原后的图像主观视觉质量明显提升,其大片天空/白墙区域的颜色失真得到有效抑制。     

A Waveguide Band-Stop Filter as an Image Rejection Filter for Measurement of Stratospheric Ozone

In this report we present the performance and test observation results of a waveguide band-stop filter (BSF) as an image rejection filter for the measurement of stratospheric ozone. By using the waveguide BSF, we are able to adopt a very simple optical system and achieve a good image rejection ratio. Additionally, we are able to observe in both single sideband (SSB) mode and double sideband (DSB) mode by only changing the local oscillator (LO) frequency. We have installed the waveguide BSF into an atmospheric ozone-measuring system using a superconductive (SIS) receiver and have successfully observed an ozone spectrum at 110 GHz in SSB and DSB mode. The receiver noise temperature (SSB) and the image rejection ratio at 110 GHz are about 60 K and more than 30 dB, respectively.Because of the IF power ripple, the waveguide BSF cannot be used with a wide-band spectrometer. However, it is quite practical for narrow-band observation.     

斜光束对校正滤色器校正精度的影响

当用测色仪器按照国际照明委员会规定的条件测量物体颜色时 ,若样品与探测器之间的距离不够大 ,则斜光束会透过校正滤色器而被探测器接收 ,这时对应探测器某点校正滤色器的当量透射比可以用修正计算式求得。以“Y”校正滤色器为例 ,从计算结果和实验说明了斜光束对校正滤色器透射比的影响。     

Switching non-local vector median filter

This paper describes a novel image filtering method that removes random-valued impulse noise superimposed on a natural color image. In impulse noise removal, it is essential to employ a switching-type filtering method, as used in the well-known switching median filter, to preserve the detail of an original image with good quality. In color image filtering, it is generally preferable to deal with the red (R), green (G), and blue (B) components of each pixel of a color image as elements of a vectorized signal, as in the well-known vector median filter, rather than as component-wise signals to prevent a color shift after filtering. By taking these fundamentals into consideration, we propose a switching-type vector median filter with non-local processing that mainly consists of a noise detector and a noise removal filter. Concretely, we propose a noise detector that proactively detects noise-corrupted pixels by focusing attention on the isolation tendencies of pixels of interest not in an input image but in difference images between RGB components. Furthermore, as the noise removal filter, we propose an extended version of the non-local median filter, we proposed previously for grayscale image processing, named the non-local vector median filter, which is designed for color image processing. The proposed method realizes a superior balance between the preservation of detail and impulse noise removal by proactive noise detection and non-local switching vector median filtering, respectively. The effectiveness and validity of the proposed method are verified in a series of experiments using natural color images.     

低照度条件下三基色获取及真彩色融合方法研究

鉴于低照度条件下彩色成像都是采用微光、红外、紫外等波段图像融合成假彩色,提出一种利用滤光片过滤和像增强器增强的三基色获取及真彩色融合方法。采用F P滤光片设计出了透射中心在三基色光中心波长的三基色滤光片,对其光谱透过性进行分析;通过旋转三基色滤色轮将目标反射光过滤,使用像增强器对过滤后反射光增强,借助FPGA编写的控制程序实现滤色轮转速和CCD摄像机成像时间的精确同步,利用CCD摄像机获取经增强后的三基色图像,实现目标三基色图像的动态采集。研制的样机在微光实验室进行了三基色采集及融合实验,实验时光照度分别1×10-1 lx （等效于月光下）和1×10-3 lx（等效于星光下）,采集速度设置为60 f/s,对获取的图像质量进行了评价。结果表明:在照度为1×10-1 lx时,融合后的真彩色图像在灰度均值、灰度方差和信息熵3项指标方面,比3幅单色图像的平均值分别提高了5.06%、5.97%和1.08%;在照度为1×10-3 lx时,融合后的真彩色图像与3幅单色图像的平均值分别提高了13.18%、-9.86和8.65%。     

三波段微光彩色夜视方法研究

为克服夜视设备产生单色图像的缺陷,得到更符合人眼视觉的彩色夜视图像。根据RGB理论模型以及滤光片的分谱作用原理,基于第二代像增强器设计出一种彩色夜视方案,通过测量滤光片的光谱透过率,得出滤光片对像增强器信噪比的影响;提出利用全波图像的四帧融合解决像增强器信噪比低的问题,并进行实验验证。实验结果显示室内和室外情况下四帧融合彩色图像熵和方差分别达到6.8、35.39及7.0、45.07,均优于三帧融合时对应值,说明提出的四帧融合方法能够克服信噪比降低的缺陷,得到清晰且信息量丰富的夜视图像。     

离焦模糊图像的维纳滤波恢复

为消除离焦误差产生的图像模糊,介绍了基于逆滤波和维纳滤波的离焦模糊图像复原方法。从光学成像原理出发,根据高斯方程计算离焦误差,建立离焦误差与光学传递函数之间的关系。讨论了离焦误差对光学成像系统传递函数的影响。通过建立线性空间不变的模糊模型,构建点扩散函数和光学传递函数,采用与模糊过程相反的处理方法进行图像复原,消除离焦误差造成的图像模糊。测试实验中,对标准样本Lena图像进行了离焦模糊处理,采用维纳滤波算法复原图像,选择不同的离焦半径和维纳滤波参数进行对比。实验结果表明:维纳滤波方法可有效消除离焦模糊;抑制噪声干扰和"振铃效应";可把图像峰值信噪比提高到6dB以上。     

一种八谱段滤光片成像系统设计

针对多光谱滤光片阵列成像采样率低,原始(Raw)数据稀疏所导致的重建图像模糊,高频信息丢失等问题,提出了一种新八谱段滤光片阵列分布方案,利用基于邻域梯度延伸方法对光谱Raw图像进行重建.首先基于二叉树生成法,在重复排列的4×4阵列中设计了一种等空间概率比的八谱段滤光片分布方案;然后针对传感器直接获取的稀疏Raw图像,计算各谱段采样点的梯度信息,在保持图像结构特征和纹理信息的基础上,利用邻域采样点的像素值和梯度值对未采样点进行重建,从而获得完整的光谱图像信息;最后,基于已重建的八谱段光谱图像,采用伪逆矩阵法重构各像素位置的31波段光谱值.结果表明,相对于主流图像重建方法,本文算法提高了重建八谱段光谱图像的峰值信噪比、复合峰值信噪比,降低了光谱均方差,更好地保留了图像的纹理和边缘,有效降低了多光谱滤光片阵列成像中的颜色伪影和图像模糊等现象.     

Narrow-band high-transmittance birefringent filter and its application in wide color gamut display

We propose a narrow-band birefringent filter and its application in wide color gamut. The birefringent filter consists of five phase retarders and two polarizers, and it has both narrow band and high transmittance. In the experiment, we fabricate the birefringent filter using quartz phase retarders and polarizers, and apply it in serval different displays. The color gamuts of displays are enhanced more than 30%NTSC(National Television System Committee), and the widest color gamuts that have been obtained are 126%NTSC in liquid crystal displays and 138%NTSC in organic light-emitting devices. Moreover,the deep blue light in spectrum of display can be reduced using the birefringent filter. The birefringent filter can be an efficient element to achieve wide color gamut display.     

光学低通滤波器的频率特性和光谱特性

光学低通滤波器是利用石英晶体的双折射效应和红外截止滤光片设计而成的。它在CCD摄像机传感器前可以有效地降低或消除离散光电探测器对不同空间频率目标成像所产生的拍频效应或条纹混叠现象,并能消除红外光对彩色还原的影响,从而提高了CCD摄像机成像的视觉效果。     

全息滤波光学图像相减

基于傅里叶光学二次滤波技术,本文提出了一种新的光学图像相减方法,即全息滤波光学图像相减法,该方法需用图像的逆转和匹配两种滤波器和一个8f光学系统,实验表明,作为一种新的图像相减方法,避免了以往实时法对光程的精细控制,因而降低了对辅助设备和环境的要求.     

非重叠背景噪声下的自适应维纳滤波模式识别方法

维纳滤波实现模式识别的关键问题是噪声知识的获得与估计。提出一种非重叠背景噪声的提取方法,首先将对噪声的粗略估计代入维纳滤波函数,得到相关峰。然后由相关峰的位置及参考图像的尺寸确定目标图像的位置和范围,从而提取出背景噪声图像。经过二次维纳滤波,得到改善的相关输出结果,实现了自适应过程。仿真结果表明在非重叠有色噪声环境下,与噪声估计法以及传统的维纳滤波方法相比,此方案具有较好的识别效果。     

基于液晶可调变滤色器的光谱图像获取及颜色重建方法

基于液晶可调变滤色器(LCTF)的光谱成像系统具有光谱分辨率高、结构紧凑、控制灵活等特点。搭建了一套可见光波段的高分辨率LCTF光谱成像系统,对系统的光谱图像获取及彩色图像重建方法进行了研究;建立了系统的光谱及颜色重建模型;基于标准色卡及标准测色系统,对该系统的颜色复现效果进行了实验验证;实验结果表明,该LCTF光谱成像系统的彩色图像颜色复现精度达可到较小色差水平。     

Log-polar transform-based wavelet-modified maximum average correlation height filter for distortion-invariant target recognition

In this paper, we report a log-polar transform-based filter for in-plane rotation and scale-invariant target recognition. The log-polar transform is a known space-invariant image representation used in several image vision systems to eliminate the effects of scale and rotation in an image. In case of in-plane rotation invariance, peaks shift horizontally, while in case of scale invariance, peaks shift vertically. For full out-of-plane rotation-invariance (0–360°), log-polar transformed images are used to train the wavelet-modified maximum average correlation height (WaveMACH) filter. Correlation peak height and peak-to-sidelobe ratio have been calculated as metrics of goodness of the log-polar transform-based WaveMACH filter. This filter would reduce the memory requirement for filter storage in a practical system. Simulation results have been presented.     

利用低通滤波作预处理对旋滤波进行改进

旋滤波方法在条纹图的处理中得到了比较广泛地应用,为了使其在噪声比较强的时候也能获得好的效果,在其方法中加入了低通滤波,以此来改善方位图,从而改善旋滤波的滤波效果。并且利用零阶开环高斯滤波算法,对低通滤波图像的边缘进行了修正。实验结果表明,改进后的方法能得到更好的条纹方位图,从而提高旋滤波的处理精度。