This talk will describe an imaging system for color appearance in mesopic vision. Haploscopic color matches were carried out to investigate the color appearance under various illuminance levels, ranging from scotopic, mesopic to photopic levels. Using these experimental data, we developed a color appearance model in any illuminance level. The model takes into account of rod intrusion both in the two color opponent channels and the luminance channel so that hue, saturation and lightness change with illuminance level. Finally, we propose an imaging system that provides color appearance of any natural scene under any illuminance level.

In industrial practice, it is often required that weighting tables were prepared in advance and tristimulus values can then be directly computed using summation of the products of the weights and measured reflectance values. The CIE has never provided precise procedure to calculate the weighting tables, and various discrepant methods have been used. Hence it is possible to obtain significantly different tristimulus values from the same set of spectral data. In order to overcome this problem, the American Society for Testing and Materials (ASTM Intl.) has published two sets of weighting tables known as Table 5 and Table 6 respectively. Each set includes 36 weighting tables covering 9 illuminants and two standard colorimetric observers at two wavelength intervals (10-nm and 20-nm). The weighting tables of Table 5 must be used with the reflectance corrected using the Stearns and Stearns (SS) method, and weighting tables of Table 6 must be used with the measured reflectance values without the SS correction. In practice, the illuminant used may be different from the CIE standard illuminants and users have to prepare their own weighting tables corresponding to the illuminant actually used. ASTM Intl. E2022-99 provided a standard calculation method to generate weighting tables of Table 5 for a non-standard illuminant. No standard procedure is given to calculate weighting tables of Table 6 since it consisted of Venable and Stearns correction weights, and the Venable optimum weight is computed by an iterative procedure. In this artical, we will report some recent progress in generating weighting tables; compare the performances among the weighting tables such as ASTM Intl. Tables of Table 5 and Table 6, Optimum weighting tables, Least Square weighting tables, and Direct selection tables; quantify the possible colorimetric errors for each of the tables; and finally recommend for standardization of a method for generating weighting tables.

In order to establish light emitting diode (LED) based spectrophotometric standard light source we used high-power Luxeon Star white LEDs having nominal electrical powers of 5W and 1W. Especially designed aluminum cooling block was used to protect LEDs from heating and to reduce heating effects on optical and electrical parameters. The chromaticity coordinate (CC) and correlated color temperature (CCT) properties of each LED were characterized by the measuring of spectral power distribution between 360 nm and 830 nm wavelength range. Then using spectral power distribution values and CIE color-matching functions at 2° observer, tristimulus values and CCs were calculated in both CIE-1931 and CIE-1960 spaces. CCTs then were calculated using computer interpolation method.

The brightness theorem states that it is impossible to increase the spectral radiance of light by passive optical devices, which seems intuitive because spectral radiance is connected to temperature; increasing it seems to violate the second law of thermodynamics. However, consider a gray thermal source, that is a source that emits thermal radiation but with less than unit emissivity. Kirchhoff's law states that absorptivity is equal to emissivity. Thus if we redirect part of the emitted radiation back onto the source, some of it would not be absorbed but either transmitted or reflected instead. Consequently, this radiation would be superposed to the thermal radiation from the source in the same phase space and thereby the spectral radiance would be increased. In fact, thermal sources such as high pressure discharge lamps feature absorptivity-emissivity values far below unity. In this contribution with spectroscopic measurement we show that for such sources the spectral brightness can be increased. This does not contradict the second law because light recycling reduces the irreversible entropy production inherent to the radiation process. It is equivalent to increasing the optical thickness of sources for the price of reducing the total phase space of emitted radiation by the same factor.

A co-occurrence matrix and Self-Organizing Map (SOM) based technique for searching images from a spectral image database is proposed. At first the SOM is trained and the Best Matching Unit (BMU) histogram is created for every spectral image of a database. Next, the texture-histogram is calculated from the co-occurrence matrices, generated using the 1st inner product images of the spectral images. BMU-histogram and the texture-histogram are combined to one feature histogram and these histograms, generated for each spectral image of a database, are saved to a histogram database. The dissimilarities between the histogram of the query image and the histograms of the database are calculated using different distance measures, more precisely Euclidean distance, dynamic partial distance and Jeffrey divergence. Finally, the images are ordered according to the histogram dissimilarity. The results using a real spectral image database are given.

Munsell color system is selected to establish the mutual conversion between RGB and L*a*b* color model for camera. The color luminance meter and CCD camera synchronously measure the same color card, the color picture captured from CCD camera is expressed for RGB value as the input of neural network; XYZ value is gotten from the color luminance meter, and the L*a*b* value converted from XYZ value is regarded as the real color value of target card, namely the output of neural network. The neural network of two hidden-layers is considered, so the second general revolving combination design is introduced into optimizing the structure of neural network, which can carry optimization through unifying project design, data processing and the precision of regression equation. Their mathematics model of encoding space is gained, and the significance inspection shows the confidence degree of regression equation is 99%. The mathematics model is optimized by genetic algorithm, optimization solution is gotten, and function value of the goal is 0.0007168. The neural network of the optimization solution is trained; the training error is 0.000748566, which the difference is not obvious comparing with forecast result; it can show that the method combining second general revolving combination design with genetic algorithm can optimize the hidden-layer structure of neural network. Using the data of testing set to test this network and calculating the color difference between forecast value and true value, the maximum is 5.6357 NBS, the minimum is 0.5311 NBS, and the average of color difference is 3.1744 NBS.

The first impression of any building to a person is its exterior and decoration, and therefore the quality of decoration project shows the more important position in building project. A lot of projects produce quality problem because of the material color difference, which exists universally at the common project, and is often found at the high-grade decoration; therefore, how to grasp and control the color change of building materials, and carry out color quantification, it has the very important meaning. According to the color theory, a computer vision system used in color quantification measurement is established, the standard illuminant A is selected as the light source. In order to realize the standardization of color evaluation, the mutual conversion between RGB and XYZ color space is studied, which is realized by the BP network. According to the colorimetry theory, the computer program is compiled in order to establish the software system, and realize the color quantitative appraisement in whole color gamut. LCH model is used at quantifying the color of building materials, and L^*a^*b^* model is used at comparing the color change. If the wooden floor is selected and laid improperly during family fitment, it is easy to present "flower face". The color also arises greater discrepancy using the laths of same tree. We can give the laying scheme using the color quantification system; at the same time, the color difference problem laying stone materials is also studied in this paper, and the solution scheme has been given using this system.

The deviations of primary display characteristics often bring about many complex chromatic aberrations on the color gamut. Among kinds of existing situations caused by deviation of primaries, the emphasis of this paper is confined to the deviation of same function family at the single primary for smoothing away differences. The purpose of this paper is two fold. First, luminance aberration of facsimile color which arises out of special deviations is discussed from many aspects and the three-dimensional gamut model of luminance aberration is proposed. The second goal is drawn on the color aberration arose from these deviations of primaries and the three-dimensional gamut with vectors has been introduced to demonstrate the feature of these aberrations whereas the difficulties of describing the distribution of color aberration. All these conclusions can be utilized to appraise the quality of the display fidelity.

Chinese ancient firelight lighting had a long history in which developed technologies were applied. The paper concerns itself with a study of Chinese ancient firelight lighting lamps, including the structures and illuminating characteristics of ancient oil lamps.

In cross-media color image reproduction, gamut mapping is needed due to gamut difference among different media. The first step of gamut mapping should be the determination of gamut boundaries of each medium involved, no matter what kind of mapping algorithm is to be used. It may be expected that an analytical expression for a boundary is preferable to a set of discrete data, since it would make the determination of the intersection point between a boundary and a "mapping line" easier and faster. This paper describes LCD display gamut boundary surfaces with a form of Zernike polynomial. In CIE1976L*a*b* color space, each color point on the boundary can be expressed as L*=L*(a*,b*) and every boundary can be expanded into a series of Zernike polynomials with appropriate coefficients. These coefficients can be obtained with sufficient experiment data of boundary points and existing algorithms. Experiments have been executed for a LCD display with(R,G,B) as its input. The 6 boundaries in RGB space would be formed respectively by (0,G,B),(R,0,B),(R,G,0),(255,G,B),(R,255,B) and (R,G,255) where each of R,G,B varies from 0 to 255. Then 6 corresponding sets of Zernike coefficients are calculated, based on about half of the measured L*a*b*'s for each boundary. A comparison between original measured data and the data predicted by Zernike polynomials shows that, not only for the data that have been used to calculate the coefficients, but also for those not used, the differences are acceptably small even negligible with only a few exceptions.

According to the chromatic theory, the color sensitive characteristic of object, light source are defined in the widely used CIE1964 (X,Y,Z) color space and color difference. Their mathematics formulae are deduced. The two kinds of color sensitive characteristic are studied. The characteristics of the color sensitive characteristic are summarized, The mathematics models of the two kinds of color sensitive characteristic can be utilized in some fields such as computer color matching, simulation standard light source.

The goal of ICC (International color consortium) color management system (CMS) is to reproduce color fidelity regardless of the hardware or platform used to capture, view or print them. The accuracy of profiles decides the precision of color conversion; therefore, creating device profiles accurately is very essential for color management. In this paper, according to the ICC standard format, we used Matrix-LUT (look up table) model, which can increase the color conversion precision to create monitor profile. In laboratory environment, we used X-Rite DPT92 to calibrate the monitor, and then we made about 1000 color patches and measured the RGB and the corresponding XYZ of each patch. We adopted linear interpolation method to establish the LUT between RGB and XYZ. The experimental results are good, and then we finished the monitor profile by the ICC format, realized CRT monitor color management.

The Light-emitting diodes based on III-nitride wide band gap semiconductors, which have a photonic crystal slab consisting of a graphite lattice of pillars on the cladding layer, is constructed. The vertical z direction optical output energy of the Light-emitting diodes is calculated by three-dimensional finite-difference time-domain method. The results show that the two-dimensional graphite-arranged pillars with a thick pillar in the middle can be utilized to enhance the light extraction. The tower-like pillars, which are thin on the top of the pillars and thick in the root of the pillars, benefit the light extraction when the angle of the tower-like pillars is proper. The optical output energy varies randomly with the change of PC columns in size and site in some extents randomly, but does not change very much.

In this paper, the spectral characteristic of solar radiation, which reaches earth surface through atmosphere, and the spectral characteristic of sky background, which is formed by molecular scattering, all of them are detailed discussed at different solar zenith angles and observation azimuth angle. The atmosphere is considered clear, that is says no clouds and aerosols. All computations base on the Rayleigh scattering law, Hitran2000 and its database. The atmosphere is divided into 32 layers extending to an altitude of 100km height as Standard Atmosphere Model. The total brightness of scattering is summation of brightness in each layer. The wavelength varies from 0.45μm to 0.95μm in the calculation. The primary reasons for choosing this band are listed followed: (1) solar radiation in this band is stronger than other band, (2) molecular scattering is more stronger in this band, (3) A few absorption regions of water vapor, such as 0.59μm, 0.65μm, 0.73μm, 0.81μm, and 0.94μm, are included in this band. The method for calculating in this band is representative and fit for all spectra regions. The paper got figures of brightness varies by observation azimuth angles at wavelength 0.6μm, solar zenith angle 45°. The calculation limits the solar azimuth angle at 0°. The result is analyzed and compared with the result acquired by Bell and his co-workers at Cocoa Beach, Florida, in 1960. The result shows brightness varied by solar zenith angles and observation azimuth angles is according with the actual observation data. The result has bright future in getting optical characteristic of target in atmosphere.

The biochemical analysis in medicine is an important inspection and diagnosis method in hospital clinic. The biochemical analysis of urine is one important item. The Urine test paper shows corresponding color with different detection project or different illness degree. The color difference between the standard threshold and the test paper color of urine can be used to judge the illness degree, so that further analysis and diagnosis to urine is gotten. The color is a three-dimensional physical variable concerning psychology, while reflectance is one-dimensional variable; therefore, the estimation method of color difference in urine test can have better precision and facility than the conventional test method with one-dimensional reflectance, it can make an accurate diagnose. The digital camera is easy to take an image of urine test paper and is used to carry out the urine biochemical analysis conveniently. On the experiment, the color image of urine test paper is taken by popular color digital camera and saved in the computer which installs a simple color space conversion (RGB -> XYZ -> L^*a^*b^*)and the calculation software. Test sample is graded according to intelligent detection of quantitative color. The images taken every time were saved in computer, and the whole illness process will be monitored. This method can also use in other medicine biochemical analyses that have relation with color. Experiment result shows that this test method is quick and accurate; it can be used in hospital, calibrating organization and family, so its application prospect is extensive.

The conical black cavities are used in the Solar Irradiance Absolute Radiometers (SIARs) of the solar constant monitor aboard on the SZ spaceship and of the Solar Total Irradiance Monitor (STIM) aboard on sun-synchronous polar orbit weather satellites. A low reflectance measurement instrument which is used for making the integrating measurement on the reflectance of the conical black cavity in a high precision within the full hemisphere (include the entrance of the Ulbrichtsphere) has been constructed. The characteristic of the instrument is the employment of a semi-transparent mirror, which is mounted in an inclination angle of 45 degrees in front of the entrance of the Ulbrichtsphere. The incident beam is reflected to the black cavity or white board by the semi-transparent mirror. A portion of those, which is made diffused reflection through the black cavity or white board, is measured by the detector located in the side face of the Ulbrichtsphere, and the other portion which is reflected to the entrance is measured by the other detector, after passing through the semi-transparent mirror, and then being focused on by an ellipsoidal mirror. The two measurement data are added up to get the integrating reflectance within full hemisphere. The presentation and verification on the measurement result of the reflectance of the black cavity and its precision are described in this article. The absolute accuracy can reach 0.012%.

The color appearance of an image is different from that of a uniform color patch because of spatial pattern effects. We have studied how the color appearance of square wave bars varies with stimulus strength and spatial frequency. The asymmetric matching method is used in the experiments, which means the color of uniform patch is adjusted by an observer to match the color appearance of the bars in square wave patterns. The square wave patterns have relatively low spatial frequencies of 1, 2, 4 and 8 cycles per degree (c p d). The area of a square wave pattern box only spreads a 2° field to the observers which means the matching is established mainly in the fovea. We find the matches are not colorimetric matches. The experiment data are analyzed and a conclusion that the cone contrast of the uniform patch is nearly proportional to the square wave stimulus strength is obtained, which reveal the property of color- homogeneity. Therefore the matches would have the basic properties of a linear system. In the article, all analyses are based on the opponent-color system. Precision of the experiments and some reasons about the data diversity are also discussed. The final conclusion suggests that the pattern separable mode could be used to predict the matches.

Organic light-emitting devices have attracted much attention owing to their potential application for flat-panel displays. How to improve their efficiency and stability are important problems which people study. Thin film OLEDs usually consist of multiple organic and metallic layers on an ITO-covered glass plate. In this paper, a single-layer device consists of a single organic layer between the anode and cathode. The single organic layer serves as the emitting source for the device, and has good bipolar character which are necessary for the transport of holes and electrons through the organic layer. The light-emitting units were based on 4,4'-bipyridine and oxadiazole derivatives. It was found that the charge carrier mobilities, charge in injection barrier, and the device performance were improved.

Spectral characterization technique has a prominent advantage that it does not suffer from the problem of metamerism in comparison with Colorimetric characterization methods. PCA (Principle Component Analysis) is an important and useful mathematical method for data reduction, in which a set of spectra, so-called statistical colorants, can be derived from spectral properties of a large set of samples. The spectral reflectance of the color, an admixture of these statistical colorants, can be represented by approximately linear addition of their spectral reflectances. In this paper, a new method for spectral characterization of a flat panel color scanner using PCA method was proposed. Firstly, the PCA algorithm was applied to estimate the spectral reflectance of the statistical colorants on the color targets scanned, and then the colorant scalars were calculated. Secondly, the relationship between the colorant scalars and the scanner RGB signals was built using BP (Back Propagation) neural network. The scanner was characterized also using polynomial regression model and BP neural network directly between scanner RGB values and divice-independent tristimulus values. The experiment results showed that the spectral characterization using PCA method was more accurate than the polynomial regression model and similarly accurate as the direct neural network method but more useful because of the accurate spectral reflectance estimation ability.

The radiometric calibration of the Time delay and integration Charge-coupled Device (TDI CCD) imaging system is a necessary part in the manufacturing TDI CCD camera. The radiometric calibration of the TDI CCD remote sensing camera is done in the State Key Laboratory of Applied Optics. The integration sphere is used for simulating different radiance, which is decided by the different sun vertex angle and different reflectivity of the ground. The parameters of the gain and stage of the TDI CCD remote sensing camera are given through the analyzing of outcome of the experiment. The outcomes are used in the practice and the errors are discussed in the end of the experiments.

Two new illumination patterns based on LEDs are discussed. White packaged LEDs with 3mm diameter and 20^o viewing angle in three cases- a single LED source, two LEDs source and a circular ring array of LEDs- are respectively adopted in the two new illumination systems. An LED light source together with condensers and light collecting lens consists of new illumination system, the other two is optical pipe illumination system. Different shapes of the optical pipe are respectively discussed. The optical systems of the two illumination patterns are designed and optimized in ZMAX, and simulated in TracePro. Compared with conventional illumination patterns, all the two new illumination patterns achieve much better performance, even illumination, high efficiency and acquiring needed illuminating size and angle. The application of LED as light sources and these two new illumination system is discussed finally.

Purpose: In this paper the chromatic contrast was defined as color difference CIEDE2000, the sensitivity was defined as reciprocal of threshold of the color difference, and the CSFs called color difference sensitivity functions were measured. Methods: The CSFs of 4 subjects were measured for nine spatial frequencies(0.28, 0.56, 1.00, 1.97, 2.95, 4.72, 6.74, 11.80 and 15.74cpd) gratings of mean luminance of 40cd/m² on a CRT display. Measurements were made for gratings whose average color was a chromatically neutral point(a*=0 and b*=0) and also for modulations around four chromatic points along the color directions a* and b* in the CIELAB color space. Results. The thresholds of color difference are from 0.74 to 6.67 in the range of experimental frequencies. The color difference sensitivity functions are similar with known results that CSF curves for the two chromatic directions are consistently low-pass irrespective of the average color of the stimulus. The sensitivity to gratings for b* direction is identical as for a* direction below spatial frequency 4.72cpd, however, the sensitivity for b* direction is smaller than the one for a* direction above spatial frequency 4.72cpd, which indicates that the CIEDE2000 threshold for grating with lower frequencies(i.e., small color differences) is not related to the chromatic direction and chromatic point of modulation, however, the threshold is related to the chromatic direction and chromatic point of modulation for large color differences.

Powder phosphors of yttrium aluminum garnet Y₃Al₅O₁₂ (YAG), activated with trivalent cerium (Ce³⁺) was synthesized by combustion from mixed metal nitrate reactants and urea with ignition temperature of 500C°~550C°. Sintering the precursor can improve the crystallization of YAG: Ce³⁺ phosphors so to promote the luminescence intensity. The influence of the concentration of Ce ³⁺ on the luminescence character was studied. The crystalline structure and morphology are observed by x-ray powder diffraction picture and SEM picture respectively.

In this paper, we propose to generalize the saccade target method and state that perceptual stability in general arises by learning the effects one's actions have on sensor responses. The apparent visual stability of color percept across saccadic eye movements can be explained by positing that perception involves observing how sensory input changes in response to motor activities. The changes related to self-motion can be learned, and once learned, used to form stable percepts. The variation of sensor data in response to a motor act is therefore a requirement for stable perception rather than something that has to be compensated for in order to perceive a stable world. In this paper, we have provided a simple implementation of this sensory-motor contingency view of perceptual stability. We showed how a straightforward application of the temporal difference enhancement learning technique yielding color percepts that are stable across saccadic eye movements, even though the raw sensor input may change radically.

In this paper, a new technique for improving the spatial resolution of hyperspectral image data will be presented. This technique combines a high-resolution image with a lower spatial resolution hyperspectral image to produce a product that has the spectral properties of the hyperspectral image at a spatial resolution approaching that of the panchromatic image. Hyperspectral imaging systems are assuming a greater importance for a wide variety of commercial and military systems. There have been several approaches to using a single higher spatial resolution band to improve the spatial resolution of the hyperspectral data. This algorithm offers a new approach to the problem of combining hyperspectral data with high-resolution images, and it is based and generally shows lower levels of error than the statistically based algorithms.

A new tool of feature extraction and recognition of color image is introduced. It is based on the quaternion representation of color image and quaternion matrix algebra, which are discussed firstly in the paper. Then the singular value (SV) feature vector of a color image is introduced and its many important properties are proved. The properties are very useful for the description and recognition of color image. Then a method for color image recognition is presented. As an application of SV feature vector, the experiment of color image recognition is made and the experiment results are satisfactory.

In industrial practice, it is often required that weighting tables were prepared in advance and tristimulus values can then be directly computed using summation of the products of the weights and measured reflectance values. The CIE has never provided precise procedure to calculate the weighting tables, and various discrepant methods have been used. Hence it is possible to obtain significantly different tristimulus values from the same set of spectral data. In order to overcome this problem, the American Society for Testing and Materials (ASTM Intl.) has published two sets of weighting tables known as Table 5 and Table 6 respectively. Each set includes 36 weighting tables covering 9 illuminants and two standard colorimetric observers at two wavelength intervals (10-nm and 20-nm). The weighting tables of Table 5 must be used with the reflectance corrected using the Stearns and Stearns (SS) method, and weighting tables of Table 6 must be used with the measured reflectance values without the SS correction. In practice, the illuminant used may be different from the CIE standard illuminants and users have to prepare their own weighting tables corresponding to the illuminant actually used. ASTM Intl. E2022-99 provided a standard calculation method to generate weighting tables of Table 5 for a non-standard illuminant. No standard procedure is given to calculate weighting tables of Table 6 since it consisted of Venable and Stearns correction weights, and the Venable optimum weight is computed by an iterative procedure. In this article, we will report some recent progress in generating weighting tables; compare the performances among the weighting tables such as ASTM Intl. Tables of Table 5 and Table 6, Optimum weighting tables, Least Square weighting tables, and Direct selection tables; quantify the possible colorimetric errors for each of the tables; and finally recommend for standardization of a method for generating weighting tables.