自适应的彩色图像光照补偿新方法

环境光照变化、光照分布不均匀会影响彩色图像中人脸的正确检测。在融合了不同的基于空域的解决方案的基础上,提出了一种自适应的彩色图像光照补偿新方法。分别对光照过亮、过暗以及中间灰度区域进行自适应的处理。对亮度值最小、最大的5%的像素,如果这些像素的数目足够多(本文大于100),在变换后分别压缩为0和255;用对数函数做非线性变换函数来修正中间灰度区域。在人脸PIE数据库上对光照不均的彩色图像进行了实验,验证了该方法能对人脸检测中的光照进行有效的补偿。     

Classifying the illumination condition from two light sources by color histogram assessment

We investigate and propose a method for assessment of the illumination condition covering two light sources. The method may be of some support for color vision and multispectral analysis methods that rely on a specific illumination condition. It is constrained to classifying the illumination condition for dielectric objects illuminated by two light sources. The reflected light is modeled by the dichromatic reflection model, which describes the light as the sum of its body reflections and surface reflections. Further, reflected light from an object illuminated by two light sources may give from one to four primary reflections depending on the condition, and it may be expressed as an additive mixture of these reflections. An additive mixture of two reflections expressed in chromaticities is limited to falling within the area enclosed by the chromaticities of the primary reflections of the light sources. So after finding the set of primary chromaticities enclosing the pixel points' chromaticities, it is possible for one to assess the current illumination condition. Since the method operates on pixel points globally, it is independent of illumination geometry and hence may be used on irregular objects. Two experiments are performed. One uses regular objects in a well-controlled laboratory environment and demonstrates that the pixel-point distribution is as expected. The second experiment demonstrates the method's potential use in support of spectroscopic analysis of vegetation through assessing the illumination condition of barley plants in an outdoor illumination condition.     

Wavelength intervals selection of illumination for separating objects from backgrounds in color vision applications

For scenes with complicated environments, the object is hard to discriminate from a background of various colors in color vision applications. This paper presents a partial least squares (PLS) method for improving discrimination of colored surfaces by selecting appropriate spectral intervals for illumination from the visible spectrum. First, the reflectance functions of all the surfaces are calibrated by multiple standard references. Second, the spectral intervals with high variables important in projection (VIP) scores of PLS analysis are selected for LED illumination. Afterwards, by using the selected wavelength intervals of LEDs for experiment, surfaces of the captured image can be clearly distinguished. Compared with the images obtained under illumination of unselected wavelength intervals of LEDs, the discriminations of most surfaces are more effective. The experiment result demonstrates the usefulness of this method.     

Context-dependent judgments of color that might allow color constancy in scenes with multiple regions of illumination

For a color-constant observer, a change in the spectral composition of the illumination is accompanied by a corresponding change in the chromaticity associated with an achromatic percept. However, maintaining color constancy for different regions of illumination within a scene implies the maintenance of multiple perceptual references. We investigated the features of a scene that enable the maintenance of separate perceptual references for two displaced but overlapping chromaticity distributions. The time-averaged, retinotopically localized stimulus was the primary determinant of color appearance judgments. However, spatial separation of test samples additionally served as a symbolic cue that allowed observers to maintain two separate perceptual references.     

黑体轨迹色温匹配的混光算法

根据实际应用的需求,从格拉斯曼颜色混合定律出发,给出了一种基于混光原理匹配黑体轨迹上色温的算法。该算法已知黑体轨迹上目标色温的色温值和色品坐标,计算出所需红、绿、蓝三原色的亮度,利用该方法可以混合出任意色温的光,实现对黑体轨迹色温的匹配。通过对几种典型色温值进行理论计算以及对可能产生的误差源进行分析,该算法计算精度较高,计算速度较快,在可调标准色温光源的设计中作为理论基础能够很好的满足色温应用的要求。     

Identification of proteins in renaissance paintings by proteomics

The presented work proposes a new methodology based on proteomics techniques to identify proteins in old art paintings. The main challenging tasks of this work were (i) to find appropriate conditions for extracting proteins from the binding media without protein hydrolysis in amino acids and (ii) to develop analytical methods adapted to the small sample quantity available. Starting from microsamples of painting models (ovalbumin-based, which is the major egg white protein, and egg-based paintings), multiple extraction solutions (HCl, HCOOH, NH3, NaOH) and conditions (ultrasonic bath, mortar and pestle, grinding resin) were evaluated. The best results were obtained using a commercial kit including a synthetic resin, mortar and pestle to grind the sample in an aqueous solution acidified with trifluoroacetic acid at 1% with additional multiple steps of ultrasonic baths. The resulting supernatant was analyzed by MALDI-TOF in linear mode to verify the efficiency of the extraction solution. An enzymatic hydrolysis step was also performed for protein identification; the peptide mixture was analyzed by nanoLC/nanoESI/Q-q-TOF MS/MS with an adapted chromatographic run for the low sample quantity. Finally, the developed methodology was successfully applied to Renaissance art painting microsamples of approximately 10 microg from Benedetto Bonfigli's triptych, The Virgin and Child, St. John the Baptist, St. Sebastian (XVth century), and Niccolo di Pietro Gerini's painting, The Virgin and Child (XIVth century), identifying, for the first time and without ambiguity, the presence of whole egg proteins (egg yolk and egg white) in a painting binder.     

温度对杨木粉末温压成形表面颜色的影响

采用CIE(1976) L~*a~*b~*系统和傅里叶红外光谱技术(FTIR),研究温压成形过程中温度对木材颜色和表面化学成分的影响规律。结果表明,成形温度升高可导致试件表面颜色加深,明度值变化范围为37. 5%～79. 2%,红绿色品指数变化范围为53. 8%～207. 7%,黄蓝色品指数变化范围为22. 4%～110. 3%;成形温度在180～200℃时ΔE~*相差1. 1,在180℃之前温度对杨木粉末的影响较为显著;随着温度的升高,半纤维素和木质素开始软化,导致试件表面颜色加深;这2类物质的降解主要存在侧链上,半纤维素降解程度高于纤维素和木质素。     

结温对高显指低色温白光LED光谱特性的影响

将MEH-PPV混合入YAG荧光粉中,并利用实验室自主研发的一种集成封装LED散热支架替代传统支架,该支架可利用热电偶直接测量出结温。研究了结温对混合MEH-PPV的白光LED光谱特性的影响。实验表明,随着结温的不断升高,蓝光光谱峰值随着结温的升高而不断下降,发生红移;荧光粉的吸收增强,黄光波段和红光波段的光谱峰值先增后减,并且红光波段的光谱发生蓝移;器件的显色指数从90.3下降至78.6,色温从3265K先快速升高至3672K,随后又缓慢下降至3612K,而光通量和发光效率则表现为先上升后下降,且它们的下降趋势基本吻合。     

Influence of the correlated color temperature of a light source on the color discrimination capacity of the observer

It is well known that there are different preferences in correlated color temperature of light sources for daily living activities or for viewing artistic paintings. There are also data relating the capacity of observers to make judgments on color differences with the spectral power distribution of the light source used. The present work describes a visual color discrimination experiment whose results confirm the existence of a relationship between the correlated color temperature of a light source and the color discrimination capacities of the observers.     

Effect of electric field,illumination, and temperature on negative magnetoresistance of low-temperature-diffusion-doped silicon

It has been experimentally demonstrated that compensated silicon doped with manganese by diffusion at a low temperature exhibits anomalously high negative magnetoresistance (MR). It is established that the negative MR magnitude in this material can be controlled by varying the temperature, illumination, and the external electric and magnetic fields.     

基于色调单维度的相关色温计算

在考察现有相关色温的定义及在CIE1960UCS、CIE1976UCS和CIE1976LAB 3种不同均匀色品图中计算值的不一致性基础上,提出了一种基于色调维度来规范计算相关色温的方法。该方法借助孟塞尔表色系统,建立色温与色调的对应关系,忽略饱和度对色温的影响,重构了3个色品图的等色温线。通过与传统相关色温计算方法比较,该方法具有物理意义更明确、在不同色品图中的计算结果一致性更好的优点。     

Initial analysis of ocean color data from the ocean color and temperature scanner. I. Imagery analysis

The ocean color and temperature scanner (OCTS) collected global ocean color data from November 1996 to June 1997. Analyses of OCTS imagery indicate three features that impair scientific research uses: (1) band misalignments, (2) image striping, and (3) image noise. These are due to (1) band offsets in the sensor design, (2) detector radiometric response variability, and (3) primarily cloud contamination, respectively. Methods are analyzed to ameliorate the effects of each that facilitate use of OCTS ocean color data for quantitative scientific analyses.     

国家色温度副基准第三次过渡定标复查

我国光源色温基准是采用两种白炽钨丝标准灯组,一组为BZ5型(6只)真空直线钨丝灯,用于2042～2353 K范围;另一组为BZ6型(5只)充气螺旋钨丝灯,用于2353～2856K范围.该项副基准建立于1975年,为保证量值的准确、一致,1987年及1997年分别进行了两次过渡定标复查.2009年,在对原光谱辐射计系统进行了部分硬件更新和恢复以后,又对该项副基准进行了第三次过渡定标复查.仍以原灯组2 042 K的平均值为基点,对每只BZ5型和BZ6型副基准灯分别进行过渡延伸定标.对复查结果和不确定度的分析表明,此次对我国色温副基准装置的恢复改造,达到了预期目的,其测量不确定度达到了该项副基准建立时的水平.     

Analysis of procedures for determining color temperature with a broad-band pyrometer having silicon and germanium photoiodides

Translated from Izmeritel'naya Tekhnika, No. 9, pp. 37–39, September, 1992.     

Nanosizing of fluorescent objects by spatially modulated illumination microscopy

A new approach to measuring the sizes of small fluorescent objects by use of spatially modulated illumination (SMI) far-field light microscopy is presented. This method is based on SME measurements combined with a new SMI virtual microscopy (VIM) data analysis calibration algorithm. Here, experimental SMI measurements of fluorescent objects with known diameter (size) were made. From the SMI data obtained, the size was determined in an independent way by use of the SMI VIM algorithm. The results showed that with SMI microscopy in combination with SMI VIM calibration, subwavelength object size measurements as small as 40 nm are experimentally feasible with high accuracy.