Articles de revues : « Chromatic system »

1

Komjáth, P. « An uncountably chromatic triple system ». Acta Mathematica Hungarica 121, n^o 1-2 (29 avril 2008) : 79–92. http://dx.doi.org/10.1007/s10474-008-7179-6.

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Deng, Bin, Hong Chen Liu, Yuan Fu Yi, Long Quan Shao, Ning Wen, Bin Gu, Yi Han Liu, Rong Jian Lu et Ji Hua Chen. « The Influence of Background Color to 3 All-Ceramic System Core Materials ». Key Engineering Materials 512-515 (juin 2012) : 1788–92. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1788.

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To study the influence of background color to 3 all-ceramic system core materials.The chromaticity value of all samples that were put on noble metal, Ni-Cr alloy, Hg-Ag alloy and resign background were measured with chromatism instrument, and chromatic aberration among groups were calculated. The chromatic aberration of Empress II samples on different background color could be distinguished by human eyes, but those of Alumina and Zirconium were unable to being distinguished. In conclusion, the influence of background color to Empress II and In-Ceram Alumina of AL1 were lager. When chosen as core material, noble metals should be covered to keep prosthesis from clinical color-transform. As background to In-Ceram Alumina of AL2, it was unnecessary for resin to be covered. In-Ceram Alumina of AL3, AL4 and In-Ceram Zirconium weren’t affected by background color.

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Jang, Seongwook, Luke D. Mayer, Hyo Mi Park, Daewook Kim et Ki-Nam Joo. « Tunable chromatic dispersion system using a geometric phase lens and refractive lens pair ». Optics Express 33, n^o 6 (14 mars 2025) : 13413. https://doi.org/10.1364/oe.554461.

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A tunable chromatic dispersion system implementing a geometric phase lens and refractive lens pair has been developed. The tunable chromatic dispersion is generated by the diffraction of the geometric phase lens and controlled by varying the distance between the geometric phase lens and a refractive lens. Because the polarization characteristics of the geometric phase lens enables its dual modes as a convex or a concave lens, the system can provide a wide range of tunable chromatic dispersion compared to traditional approaches. The system performance is theoretically analyzed, modeled, simulated, and experimentally verified. Chromatic dispersion ranging from -3.8 mm to 4.4 mm was successfully demonstrated. Furthermore, various factors that influence the spectral resolution were investigated for the chromatic confocal sensor application.

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Xingyao Gu, Xingyao Gu, Hongwei Chen Hongwei Chen, Minghua Chen Minghua Chen et Shizhong Xie Shizhong Xie. « 160 km all-optical OFDM transmission system with inline chromatic dispersion compensation ». Chinese Optics Letters 10, n^o 2 (2012) : 020601–20604. http://dx.doi.org/10.3788/col201210.020601.

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Li, Hui, Xin Tan, Qingbin Jiao, Yuhang Li, Siqi Liu, Jian Pei, Jiahang Zhang, Wei Zhang et Liang Xu. « Design and Study of a Reflector-Separated Light Dispersion-Compensated 3D Microscopy System ». Sensors 23, n^o 9 (6 mai 2023) : 4516. http://dx.doi.org/10.3390/s23094516.

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The secondary-phase grating-based tomographic microscopy system, which is widely used in the biological and life sciences, can observe all the sample multilayer image information simultaneously because it has multifocal points. However, chromatic aberration exists in the grating diffraction, which seriously affects the observation of the image. To correct the chromatic aberration of the tomographic microscope system, this paper proposes a system that adopts blazed gratings and angle-variable reflectors as chromatic aberration correction devices according to the principle of dispersion compensation and Fourier phase-shift theory. A reflector-separated light dispersion-compensated 3D microscopy system is presented to achieve chromatic aberration correction while solving the problem of multilayer image overlap. The theoretical verification and optical design of the system were completed using ZEMAX software. The results show that the proposed system reduced the chromatic aberration of ordinary tomographic microscopy systems by more than 90%, retaining more wavelengths of light information. In addition, the system had a relatively wide range in the color difference compensation element installation position, reducing the difficulty of dispersion compensation element installation. Overall, the results indicate that the proposed system is effective in reducing chromatic aberration in grating diffraction.

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Almajali, Ziyad S. « HVDC Faults Classification by Lab Color Based Monitoring System ». WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL 17 (29 avril 2022) : 186–92. http://dx.doi.org/10.37394/23203.2022.17.21.

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This paper presents a new method for faults classification of HVDC system by analyzing the currents and voltages of the system under the Zero-Direct-Quadrature (DQ0) coordinates using Lab color chromatic based monitoring approach. Repeated for several healthy and faulty scenarios in DC side and AC side as well, The DQ0 transformed signals are evaluated for each case, Continuous chromatic monitoring is applied on all signals. A chromatic Lab mapping of short time-slot windows result in providing an early fault detection. The preliminary results show high accuracy in fault type classification as well with short processing time and without the need for any pretraining requirement.

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MIYATAKE, Tsutomu, et Shiro HAMADA. « Chromatic Bifocus Alignment System for SR Stepper. » Journal of the Japan Society for Precision Engineering 59, n^o 5 (1993) : 749–54. http://dx.doi.org/10.2493/jjspe.59.749.

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Bilodeau, Lynda, et Jocelyn Faubert. « Global motion cues and the chromatic system ». Journal of the Optical Society of America A 16, n^o 1 (1 janvier 1999) : 1. http://dx.doi.org/10.1364/josaa.16.000001.

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Bause, George S. « De Jarnette’s Optic Chromatic System of Anesthesia ». Anesthesiology 119, n^o 1 (1 juillet 2013) : 177. http://dx.doi.org/10.1097/aln.0b013e31829e4001.

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Zhang, Yuzhuo, Yaqin Sun, Nan Gao, Zhaozong Meng et Zonghua Zhang. « Phase Target-Based Calibration of Projector Radial Chromatic Aberration for Color Fringe 3D Measurement Systems ». Sensors 22, n^o 18 (9 septembre 2022) : 6845. http://dx.doi.org/10.3390/s22186845.

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The camera and projector are indispensable hardware parts of a color fringe projection 3D measurement system. Chromatic aberration between different color channels of the projector and camera has an impact on the measurement accuracy of the color fringe projection 3D profile measurement. There are many studies on camera calibration, but the chromatic aberration of the projector remains a question deserving of further investigation. In view of the complex system architecture and theoretical derivation of the traditional projector radial chromatic aberration method, a phase target based on projector radial chromatic aberration measurement and the correction method are proposed in this paper. This method uses a liquid crystal display with a holographic projection film as the phase target. The liquid crystal display sequentially displays red, green, and blue horizontal and vertical sinusoidal fringe images. The projector projects red, green, and blue horizontal and vertical sinusoidal fringe images to the phase target in turn, and calculates the absolute phases of the display fringes and reflection fringes, respectively. Taking the green channel as the reference channel, a phase coordinate system is established based on the phases of the vertical and horizontal directions displayed on the display screen, using the phase of the reflection fringes on the display screen as the ideal phase value of the phase point. Then, the phase coordinate system of the red and blue channels is transferred to the green phase coordinate system to calculate the chromatic aberration of the red-green channels and the blue-green channels, and pre-compensation is conducted. Experimental results prove that this method can measure and calibrate the radial chromatic aberration of the projector without being affected by the image quality of the camera. The correction effect of this method is that the maximum chromatic aberration of the red-green channel decreases from 1.9591/pixel to 0.5759/pixel, and the average chromatic aberration decreases from 0.2555/pixel to 0.1865/pixel. In addition, blue-green channel maximum chromatic aberration decreased from 1.8906/pixel to 0.5938/pixel, and the average chromatic aberration decreased from 0.2347/pixel to 0.1907/pixel. This method can improve the projection quality for fringe projection 3D profile measurement technology.

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Jones, G. R., P. Russell et I. Khandaker. « Chromatic interferometry for an intelligent plasma processing system ». Measurement Science and Technology 5, n^o 6 (1 juin 1994) : 639–47. http://dx.doi.org/10.1088/0957-0233/5/6/002.

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12

Smithson, H. E., et J. D. Mollon. « Is the S-opponent chromatic sub-system sluggish ? » Vision Research 44, n^o 25 (novembre 2004) : 2919–29. http://dx.doi.org/10.1016/j.visres.2004.06.022.

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13

Yeh, Hong-Gwa, et Xuding Zhu. « Resource-sharing system scheduling and circular chromatic number ». Theoretical Computer Science 332, n^o 1-3 (février 2005) : 447–60. http://dx.doi.org/10.1016/j.tcs.2004.12.005.

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Shirashige, Yu, Hideaki Orii, Hideaki Kawano, Hiroshi Maeda et Norikazu Ikoma. « Chromatic Vision Support System with Color Conversion Constraints ». Journal of Advanced Computational Intelligence and Intelligent Informatics 17, n^o 2 (20 mars 2013) : 176–84. http://dx.doi.org/10.20965/jaciii.2013.p0176.

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The symptoms of “color blindness” are due to an innate lack or deficit of “cone cells” that recognize colors. People with color blindness have difficulty discriminating combinations of specific colors. In this study, we developed a system to support color blindness. In this system, the brightness of colors is modified using a projector-camera system. Images that contain combinations of specific colors are difficult to discriminate using a camera, so this task is performed by a projector. We conducted experiments, to validate our proposed system using various color combinations.

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15

Lin, Tzu-Yang, Jiangnan Luo, Kazunori Shinomiya, Chun-Yuan Ting, Zhiyuan Lu, Ian A. Meinertzhagen et Chi-Hon Lee. « Mapping chromatic pathways in the Drosophila visual system ». Journal of Comparative Neurology 524, n^o 2 (11 août 2015) : 213–27. http://dx.doi.org/10.1002/cne.23857.

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Lin, Tzu-Yang, Jiangnan Luo, Kazunori Shinomiya, Chun-Yuan Ting, Zhiyuan Lu, Ian A. Meinertzhagen et Chi-Hon Lee. « Mapping chromatic pathways in the Drosophila visual system ». Journal of Comparative Neurology 524, n^o 2 (9 décembre 2015) : Spc1. http://dx.doi.org/10.1002/cne.23936.

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17

Jeong, Dawoon, Se Jin Park, Hansol Jang, Hyunjoo Kim, Jaesun Kim et Chang-Seok Kim. « Swept-Source-Based Chromatic Confocal Microscopy ». Sensors 20, n^o 24 (21 décembre 2020) : 7347. http://dx.doi.org/10.3390/s20247347.

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Chromatic confocal microscopy (CCM) has been intensively developed because it can exhibit effective focal position scanning based on the axial chromatic aberration of broadband light reflected from a target. To improve the imaging speed of three-dimensional (3D) surface profiling, we have proposed the novel concept of swept-source-based CCM (SS-CCM) and investigated the usefulness of the corresponding imaging system. Compared to conventional CCM based on a broadband light source and a spectrometer, a swept-source in the proposed SS-CCM generates light with a narrower linewidth for higher intensity, and a single photodetector employed in the system exhibits a fast and sensitive response by immediately obtaining spectrally encoded depth from a chromatic dispersive lens array. Results of the experiments conducted to test the proposed SS-CCM system indicate that the system exhibits an axial chromatic focal distance range of approximately 360 μm for the 770–820 nm swept wavelength range. Moreover, high-speed surface profiling images of a cover glass and coin were successfully obtained with a short measurement time of 5 ms at a single position.

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18

Yadgeer, Saniya Anjum, S. Ray et P. V. Joglekar. « Study of Chromatic Dispersion in Single-Mode Optical Fiber ». Journal of Physics : Conference Series 2426, n^o 1 (1 février 2023) : 012026. http://dx.doi.org/10.1088/1742-6596/2426/1/012026.

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Abstract In the optical communication system, optical fibers are used to transmit information in a long-haul communication system at a very high speed. However, attenuation causes loss in signal transmission. Chromatic dispersion is an ultimate limiting factor for attenuation in high-speed long-distance communication. The chromatic dispersion causes a broadening of the incident pulse while traversing along the fiber length. This broadening reduces the information-carrying capacity of the transmitted signal. Chromatic dispersion is caused by material and waveguide dispersion. We used COMSOL Multiphysics to evaluate chromatic dispersion for the different refractive indexes of silica glass by varying wavelengths from 1300 (nm) to 1600 (nm). We have modelled a 2D optical fiber using the Electromagnetic Wave, Frequency Domain. The effective mode index was computed using Mode Analysis and total dispersion is calculated theoretically. The computed values of chromatic dispersion are within 7% of theoretical values.

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Olvera-Angeles, Miguel, Justo Arines et Eva Acosta. « Chromatic Aberration in Wavefront Coding Imaging with Trefoil Phase Mask ». Photonics 11, n^o 12 (26 novembre 2024) : 1117. http://dx.doi.org/10.3390/photonics11121117.

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The refractive index of the lenses used in optical designs varies with wavelength, causing light rays to fail when focusing on a single plane. This phenomenon is known as chromatic aberration (CA), chromatic distortion, or color fringing, among other terms. Images affected by CA display colored halos and experience a loss of resolution. Fully achromatic systems can be achieved through complex and costly lens designs and/or computationally when digital sensors capture the image. In this work, we propose using the wavefront coding (WFC) technique with a trefoil-shaped phase modulation plate in the optical system to effectively increase the resolution of images affected by longitudinal chromatic aberration (LCA), significantly simplifying the optical design and reducing costs. Experimental results with three LEDs simulating RGB images verify that WFC with trefoil phase plates effectively corrects longitudinal chromatic aberration. Transverse chromatic aberration (TCA) is corrected computationally. Furthermore, we demonstrate that the optical system maintains depth of focus (DoF) for color images.

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Tong, Li Ping, Bin Peng, Yi Wei Fei et Hong Wei Yang. « Application of CIEDE2000 Color Difference Formula in Jet Fuel Silver Strip Corrosion Color Recognition ». Key Engineering Materials 531-532 (décembre 2012) : 54–57. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.54.

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In order to eliminate the human eyes’ subjective differences in the level recognition of the jet fuel’s silver corrosion, chromatic aberration system is used to calculate chromatic aberration between the image of the standard colorimetric board and the experiment silver corrosion. By contrast, this paper chooses the least chromatic aberration to estimate the level of silver corrosion. The CIEDE2000 of the color difference formula, which can match with person vision theoretically, is applied in the chromatic aberration system at present, and can reflect the minor differences in color correctly. so this paper attempts to use CIEDE2000 color formula to determine the silver strip corrosion, which can reduce the influence of professionals’ subjective factors, and these results are more objective and accurate, which proves the actual feasibility of this method.

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Goda, Naokazu, et Yoshimichi Ejima. « Moving Stimuli Define the Shape of Stationary Chromatic Patterns ». Perception 26, n^o 11 (novembre 1997) : 1413–22. http://dx.doi.org/10.1068/p261413.

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A study is reported of phenomena involved in perceptually unified organisation of a stationary chromatic pattern and a moving black outline or dot pattern. When the corners of the outline pattern were temporally oscillated on a stationary chromatic square, the chromatic border appeared to follow the moving outline, as if captured by it. This capture effect was also observed with moving dots: the chromatic border was defined by an imaginary line connecting the moving dots. Both capture effects occur over a region that becomes wider with increasing velocity of the oscillation. These observations suggest that the visual system effectively uses information from moving features to define the shape of overlapping chromatic image regions.

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Sudha, S., B. Shoba, A. Rajkumar et Broumi Said. « Bipolar Triangular Neutrosophic Chromatic Numbers with the Application of traffic light system ». International Journal of Neutrosophic Science 22, n^o 2 (2023) : 54–67. http://dx.doi.org/10.54216/ijns.220205.

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For addressing issues in several domains, such as theoretical computer science, engineering, physics, combinatorics, and the medical sciences, graph theory is a crucial component of mathematics. Graph coloring is one of the new settings that is emerging in a neutrosophic chromatic number environment. In addition to introducing the idea of bipolar triangular neutrosophic chromatic graphs (BTNCG), this work also examines and demonstrates the algebraic assumption. The proposed concept has been applied in a traffic signal system to discover a new lane to avoid traffic in peak hours.

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Cerda-Company, Xim, Olivier Penacchio et Xavier Otazu. « Chromatic Induction in Migraine ». Vision 5, n^o 3 (6 août 2021) : 37. http://dx.doi.org/10.3390/vision5030037.

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The human visual system is not a colorimeter. The perceived colour of a region does not only depend on its colour spectrum, but also on the colour spectra and geometric arrangement of neighbouring regions, a phenomenon called chromatic induction. Chromatic induction is thought to be driven by lateral interactions: the activity of a central neuron is modified by stimuli outside its classical receptive field through excitatory–inhibitory mechanisms. As there is growing evidence of an excitation/inhibition imbalance in migraine, we compared chromatic induction in migraine and control groups. As hypothesised, we found a difference in the strength of induction between the two groups, with stronger induction effects in migraine. On the other hand, given the increased prevalence of visual phenomena in migraine with aura, we also hypothesised that the difference between migraine and control would be more important in migraine with aura than in migraine without aura. Our experiments did not support this hypothesis. Taken together, our results suggest a link between excitation/inhibition imbalance and increased induction effects.

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Journal, Baghdad Science. « A proposed Mathematical Expression for Computer Design of Electrostatic Mirror ». Baghdad Science Journal 9, n^o 1 (4 mars 2012) : 148–52. http://dx.doi.org/10.21123/bsj.9.1.148-152.

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A computational investigation has been carried out on the design and properties of the electrostatic mirror. In this research, we suggest a mathematical expression to represent the axial potential of an electrostatic mirror. The electron beam path under zero magnification condition had been investigated as mirror trajectory with the aid of fourth – order – Runge – Kutta method. The spherical and chromatic aberration coefficients of mirror has computed and normalized in terms of the focal length. The choice of the mirror depends on the operational requirements, i.e. each optical element in optical system has suffer from the chromatic aberration, for this case, it is use to operate the mirror in optical system at various values of chromatic aberration to correct it in that system.

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Mohammed, Mahdi A. « A proposed Mathematical Expression for Computer Design of Electrostatic Mirror ». Baghdad Science Journal 9, n^o 1 (4 mars 2012) : 148–52. http://dx.doi.org/10.21123/bsj.2012.9.1.148-152.

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A computational investigation has been carried out on the design and properties of the electrostatic mirror. In this research, we suggest a mathematical expression to represent the axial potential of an electrostatic mirror. The electron beam path under zero magnification condition had been investigated as mirror trajectory with the aid of fourth – order – Runge – Kutta method. The spherical and chromatic aberration coefficients of mirror has computed and normalized in terms of the focal length. The choice of the mirror depends on the operational requirements, i.e. each optical element in optical system has suffer from the chromatic aberration, for this case, it is use to operate the mirror in optical system at various values of chromatic aberration to correct it in that system.

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Jing-wu, ZOU, YU Qing et CHENG Fang. « Differential chromatic confocal roughness evaluation system and experimental research ». Chinese Optics 13, n^o 5 (2020) : 1103–14. http://dx.doi.org/10.37188/co.2020-0029.

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GAO Xin, 高鑫, 邓文怡 DENG Wenying et 牛春晖 NIU Chunhui. « Research of displacement measurement system based on chromatic confocal ». Optical Technique 38, n^o 1 (2012) : 83–88. http://dx.doi.org/10.3788/gxjs20123801.0083.

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Wei Xiaoxiao, 韦晓孝, 许峰 Xu Feng et 余建军 Yu Jianjun. « Study of Chromatic Aberration of Pan-Cassegrain Optical System ». Acta Optica Sinica 32, n^o 7 (2012) : 0722002. http://dx.doi.org/10.3788/aos201232.0722002.

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Wuerger, Sophie M., Michael J. Morgan, Steve Westland et Huw Owens. « The spatio-chromatic sensitivity of the human visual system ». Physiological Measurement 21, n^o 4 (1 novembre 2000) : 505–13. http://dx.doi.org/10.1088/0967-3334/21/4/307.

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Zhang, Yuning, Xiuli Zhu, Ao Liu, Yishi Weng, Zhongwen Shen et Baoping Wang. « Modeling and optimizing the chromatic holographic waveguide display system ». Applied Optics 58, n^o 34 (7 octobre 2019) : G84. http://dx.doi.org/10.1364/ao.58.000g84.

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MAHMUD, S. H. « Frequency specific chromatic adaptation in the human visual system ». Scandinavian Journal of Psychology 27, n^o 1 (mars 1986) : 340–45. http://dx.doi.org/10.1111/j.1467-9450.1986.tb01212.x.

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Solomon, S., C. Tailby et P. Lennie. « Regulation of chromatic sensitivity in the primate visual system ». Journal of Vision 7, n^o 15 (28 mars 2010) : 2. http://dx.doi.org/10.1167/7.15.2.

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van der Laan, G., et H. A. Padmore. « A chromatic premirror system for a double-crystal monochromator ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 291, n^o 1-2 (mai 1990) : 225–27. http://dx.doi.org/10.1016/0168-9002(90)90065-e.

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Wang, Xingzheng, Bob Zhang, Zhenhua Guo et David Zhang. « Facial image medical analysis system using quantitative chromatic feature ». Expert Systems with Applications 40, n^o 9 (juillet 2013) : 3738–46. http://dx.doi.org/10.1016/j.eswa.2012.12.079.

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Nagaki, Yoshiro, Akira Taniguchi, Takeshi Tsukamoto et Takao Tanimoto. « System to measure the chromatic dispersion of optical fibers ». Electronics and Communications in Japan (Part I : Communications) 77, n^o 1 (janvier 1994) : 26–36. http://dx.doi.org/10.1002/ecja.4410770103.

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Cesar, João Carlos de Oliveira. « Chromatic harmony in architecture and the Munsell color system ». Color Research & ; Application 43, n^o 6 (13 novembre 2018) : 865–71. http://dx.doi.org/10.1002/col.22283.

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Zhao, Yan, Li Sheng Zhao, Jian Feng Chen, Bin Deng, Bin Gu, Yuan Fu Yi, Long Quan Shao, Zheng Wang et Ning Wen. « The Programming of Dentistry CCS/CCM Software ». Key Engineering Materials 544 (mars 2013) : 502–6. http://dx.doi.org/10.4028/www.scientific.net/kem.544.502.

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Objective: We aimed to develop a multi-functional CCS/CCM (Computerized Color Selecting/Computer Color Matching) software so as to provide more practical colorimetric software for clinical use and further researches. Methods: This software used the 6 dental prosthetic materials and color data from 4 shade guide system which were most frequently-used in clinic currently as basic database, to program 5 functional blocks including respectively CCS/CCM system; Dental Material Chromatic Value System; Vita Information System; Transformation of Colorimeter System; and Chromatic Value Difference Analysis. These modules had the functions of information inquiry of different types of dental materials and their corresponding chromatic value, color matching, transforming, and color difference analysis. Results: The software had a convenient operation interface which could guarantee a stable performance. Containing various shade block and chromatic value, and transformation among different colors, this software analysed the color difference in the database, improved the accuracy and reliability of dental color choosing, and, to some extent, increased the color repetition rate of prosthesis. Conclusion: The software could well meet the needs of clinical dental colorimeter and choosing, increase the color repetition rate of prosthesis, and easily finish the transformation among different colors. It had more functions to adapt clinical need.

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Deng, Yangchun, Junlei Zhao, Yun Dai et Yudong Zhang. « Simultaneous quantification of longitudinal and transverse ocular chromatic aberrations with Hartmann–Shack wavefront sensor ». Journal of Innovative Optical Health Sciences 11, n^o 04 (juillet 2018) : 1850021. http://dx.doi.org/10.1142/s1793545818500219.

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A simple method to objectively and simultaneously measure eye’s longitudinal and transverse chromatic aberrations was proposed. A dual-wavelength wavefront measurement system using two Hartmann–Shack wavefront sensors was developed. The wavefronts of the red (639.1[Formula: see text]nm) and near-infrared (786.0[Formula: see text]nm) lights were measured simultaneously for different positions in the model eye. The chromatic wavefronts were converted into Zernike polynomials. The Zernike tilt coefficient (first term) was used to calculate the transverse chromatic aberration along the [Formula: see text]-direction, while the Zernike defocus coefficient (fourth term) was used to calculate the longitudinal chromatic aberration. The measurement and simulation data were consistent.

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Reshidko, Dmitry, Masatsugu Nakanato et José Sasián. « Ray Tracing Methods for Correcting Chromatic Aberrations in Imaging Systems ». International Journal of Optics 2014 (2014) : 1–11. http://dx.doi.org/10.1155/2014/351584.

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The correction of chromatic aberrations is typically performed using aberration formulas or by using real ray tracing. While the use of aberration formulas might be effective for some simple optical systems, it has limitations for complex and fast systems. For this reason chromatic aberration correction is usually accomplished with real ray tracing. However, existing optimization tools in lens design software typically mix the correction of monochromatic and chromatic aberrations by construction of an error function that minimizes both aberrations at the same time. This mixing makes the correction of one aberration type dependent on the correction of the other aberration type. We show two methods to separate the chromatic aberrations correction of a lens system. In the first method we use forward and reverse ray tracing and fictitious nondispersive glasses, to cancel the monochromatic aberration content and allow the ray tracing optimization to focus mainly on the color correction. On the second method we provide the algorithm for an error function that separates aberrations. Furthermore, we also demonstrate how these ray tracing methods can be applied to athermalize an optical system. We are unaware that these simple but effective methods have been already discussed in detail by other authors.

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Cohen-Sabban, Joseph. « Merging Phase Shifting Interferometry with Confocal Chromatic Microscopy ». Key Engineering Materials 381-382 (juin 2008) : 287–90. http://dx.doi.org/10.4028/www.scientific.net/kem.381-382.287.

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The implementation of the basic physical principle of Chromatic Confocal Microscopy in the field of Phase stepping interferometry (PSI) opens new opportunities for the development of an innovative surface metrology method specially dedicated to 3D nanotopography with subnanometric z axis resolution altogether with a very large measuring range: typically up to one hundred micrometers. The basic property of optical sectioning inherent to (chromatic) Confocal imaging is particularly well adapted to Phase stepping Interferometry since it automatically solves the critical and time consuming problem of phase unwrapping computation. The axial chromatic extension of the chromatic confocal setup offers a very fast and easy way to determine the height of the different elementary surfaces forming the measured object. It is then easy to carry out, for each one of those elementary surfaces, a measurement in phase shifting interferometry, at the wavelength corresponding to the altitude indicated by the confocal chromatic, in order to reach subnanometric axial resolutions. The four phases needed for implementing the phase stepping interferometric measuring procedure can be successively realized by adequate spectral shifts instead of the classical axial displacements of the reference mirror which then stands in a fixed position. Consequently this chromatic confocal phase stepping interferometer (CCPSI) has definitely no moving part, the spectral shifts being done by electrooptical means. Typical applications are MEMS and microoptics surface topography and/or roughness metrology. For this purpose we designed a new system incorporating confocal chromatic imaging and phase stepping interferometry. As a direct consequence of the optical sectioning property, this system allows measuring through any type of optical window (for example a cover glass).

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Railo, Henry, Niina Salminen-Vaparanta, Linda Henriksson, Antti Revonsuo et Mika Koivisto. « Unconscious and Conscious Processing of Color Rely on Activity in Early Visual Cortex : A TMS Study ». Journal of Cognitive Neuroscience 24, n^o 4 (avril 2012) : 819–29. http://dx.doi.org/10.1162/jocn_a_00172.

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Chromatic information is processed by the visual system both at an unconscious level and at a level that results in conscious perception of color. It remains unclear whether both conscious and unconscious processing of chromatic information depend on activity in the early visual cortex or whether unconscious chromatic processing can also rely on other neural mechanisms. In this study, the contribution of early visual cortex activity to conscious and unconscious chromatic processing was studied using single-pulse TMS in three time windows 40–100 msec after stimulus onset in three conditions: conscious color recognition, forced-choice discrimination of consciously invisible color, and unconscious color priming. We found that conscious perception and both measures of unconscious processing of chromatic information depended on activity in early visual cortex 70–100 msec after stimulus presentation. Unconscious forced-choice discrimination was above chance only when participants reported perceiving some stimulus features (but not color).

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LUTZE, MARGARET, JOEL POKORNY et VIVIANNE C. SMITH. « Achromatic parvocellular contrast gain in normal and color defective observers : Implications for the evolution of color vision ». Visual Neuroscience 23, n^o 3-4 (mai 2006) : 611–16. http://dx.doi.org/10.1017/s0952523806233078.

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The PC pathway conveys both chromatic and achromatic information, with PC neurons being more responsive to chromatic (L−M) than to achromatic (L+M) stimuli. In considering the evolution of color vision, it has been suggested that the dynamic range of chromatic PC-pathway processing is tuned to the chromatic content of the natural environment. Anomalous trichromats, with reduced separation of their L- and M-cone spectral sensitivities, have diminished chromatic input to PC-pathway cells. Dichromats, with absent L or M cones, should have no chromatic input to PC-pathway cells. Therefore, the PC-pathway dynamic range of color defectives should be released from any constraint imposed by the chromatic environment. Here we ask whether this results in compensatory enhancement of achromatic PC-pathway processing in color defectives. This study employed a psychophysical method designed to isolate PC-pathway processing using achromatic stimuli. In a pulsed-pedestal condition, a four-square stimulus array appeared within a uniform surround. During a trial, one of the test squares differed from the other three, and the observer's task was to choose the square that was different. A four-alternative, forced-choice method was used to determine thresholds as a function of the contrast of the four-square array to the surround. Seven color defective and four normal observers participated. Results showed no systematic differences between normals and color defectives. There was no enhancement of achromatic processing as compensation for reduced chromatic processing in the PC-pathway system in color defectives. From physiological recordings, PC-pathway achromatic contrast gains of dichromatic and trichromatic New World primates and trichromatic Old World macaques have also been shown to be similar to each other. Our study and the animal studies imply that PC-pathway contrast gain parameters were regulated by factors other than the environmental chromaticity gamut, and may have arisen in a nontrichromatic common ancestor to both Old and New World primates.

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MOROZANU, Cristina. « The semiotics of color names in christian poetry ». Univers Pedagogic 85, n^o 1 (mars 2025) : 58–65. https://doi.org/10.52387/1811-5470.2025.1.08.

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In this article we describe the chromatic terms in Christian poetry through the lens of semiotics. The analysis of the lexical-semantic system of color names on the paradigmatic and syntagmatic axis allowed us to establish the character of the relationships between the chromatic terms of the semantic field of color names, to highlight the variety of meanings and connotative features of these terms, realized in different semantic areas. This creates a comprehensive view of the semantic, aesthetic, and affective possibilities of chromatic lexemes in Christian poetry, with potential applications in teaching.

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Shen, Che, et Mark D. Fairchild. « Weighted Geometric Mean (WGM) method : A new chromatic adaptation model ». PLOS ONE 18, n^o 8 (14 août 2023) : e0290017. http://dx.doi.org/10.1371/journal.pone.0290017.

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The human visual system has undergone evolutionary changes to develop sophisticated mechanisms that enable stable color perception under varying illumination. These mechanisms are known as chromatic adaptation, a fundamental aspect of color vision. Chromatic adaptation can be divided into two categories: sensory adaptation, which involves automatic adjustments in the visual system, such as retinal gain control, in response to changes in the stimulus, and cognitive adaptation, which depends on the observer’s knowledge of the scene and context. The geometric mean has been suggested to be the fundamental mathematical relationship that governs peripheral sensory adaptation. This paper proposes the WGM model, an advanced chromatic adaptation model based on a weighted geometric mean approach that can anticipate incomplete adaptation as it moves along the Planckian or Daylight locus. Compared with two other chromatic adaptation models (CAT16 and vK20), the WGM model is tested with different corresponding color data sets and found to be a significantly improvement while also predicting degree of adaptation (sensory and cognitive adaptation) in a physiologically plausible manner.

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Girard, Pascal, et Maria Concetta Morrone. « Spatial structure of chromatically opponent receptive fields in the human visual system ». Visual Neuroscience 12, n^o 1 (janvier 1995) : 103–16. http://dx.doi.org/10.1017/s0952523800007355.

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AbstractThis study investigates the receptive-field structure of mechanisms operating in human color vision, by recording visual evoked potentials (VEPs) to multiharmonic gratings modulated either in luminance or color (red-green). Varying the Fourier phase of the harmonics from 0 deg to 90 deg produced a family of stimulus profiles that varied from lines to edges. The stimuli were contrast reversed to elicit steady-state VEPS, and also randomly jittered (at a higher temporal frequency than the contrast reversal) to ensure that the evoked response resulted from the polarity reversal, rather than from local variation of luminance or color. Reliable VEPs were recorded from both luminance and chromatic stimuli at all phases, suggesting that the mechanisms sensitive to chromatic contrast and those sensitive to luminance contrast have both symmetric and asymmetric receptive fields. Contrast thresholds estimated by extrapolation of the contrast response curves were very similar to psychophysical thresholds for phase discrimination, suggesting that the VEP response is generated by mechanisms mediating phase discrimination. The results support the idea that human color mechanisms have receptive fields with a variety of spatial symmetries (including odd- and even-symmetric fields) and that these mechanisms may contribute to phase discrimination of chromatic stimuli in a similar way to what has been suggested for luminance vision.

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Stepanyan, Ivan V., et Mihail Y. Lednev. « Chromatic Differentiation of Functional Mappings of the Composition of Nucleic Acids ». Symmetry 15, n^o 4 (20 avril 2023) : 942. http://dx.doi.org/10.3390/sym15040942.

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Color visualization of the DNA of diverse living beings can help in the exploration of the issue of chromatic differentiation of functional mappings of the nucleotide composition of DNA molecules. By “chromatic differentiation”, we mean the coloring of these mappings. Algorithms for coloring genetic representations improve the perception of complex genetic information using color. Methodologically, to build the chromatic differentiation of functional mappings of the nucleotide composition of DNA, we employed the system of nucleotide Walsh functions and the Chaos Game Representation (CGR) algorithm. The authors compared these two approaches and proposed a modified CGR algorithm. The work presents various algorithms of chromatic differentiation based on the nucleotide Walsh functions at a specific location of the fragment in the nucleotide chain and on the frequencies of those fragments. The results of the analysis provide examples of chromatic differentiation in a variety of parametric spaces. The paper describes various approaches to coloring and video animation of DNA molecules in their chromatically differentiated spans of physicochemical parameters.

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Liu, Ying, Zhao-Hua Yang, Yuan-Jin Yu, Ling-An Wu, Ming-Yue Song et Zhi-Hao Zhao. « Chromatic-Aberration-Corrected Hyperspectral Single-Pixel Imaging ». Photonics 10, n^o 1 (22 décembre 2022) : 7. http://dx.doi.org/10.3390/photonics10010007.

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With the emerging development of hyperspectral single-pixel imaging (SPI) systems, the trade-off between the simplicity of optical structure and the correction of chromatic aberration is now an essential factor to be considered. To address both issues simultaneously, we propose a chromatic-aberration-corrected hyperspectral single-pixel imaging scheme, which is based on spectral measurement and dispersion correction. Its achromatism feature is evaluated by optical simulations and proof-of-concept experiments. Moreover, to overcome the shortcomings of traditional algorithms, a new adaptive iterative algorithm is employed, which can further optimize image quality. The results demonstrate that both dispersion and noise in our system are significantly reduced. Taking the position coordinate variance as a figure of merit, we have realized an order of magnitude improvement in the lateral chromatic aberration over the spectral range of 400–780 nm compared to that in conventional hyperspectral SPI. Meanwhile, the contrast-to-noise ratio in our system is enhanced on average by 3 dB. To the best of our knowledge, this is the first such demonstration, and the technique presents possibilities for future integrated applications of high spatial/spectral resolution over the entire visible range, and the system has the potential to be scaled down for future integrated applications.

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Li, Meiqi. « Accurate Recognition of Motion Patterns Based on Artificial Visual Neural Network ». Advances in Multimedia 2022 (4 juillet 2022) : 1–14. http://dx.doi.org/10.1155/2022/4321750.

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In order to improve the accuracy of motion pattern recognition, this paper combines the artificial visual neural network to construct a motion pattern recognition system. Moreover, this paper discusses the psychological perception properties of human eyes to color stimuli and gives a description of the observation field of view where the color stimuli are located. At the same time, this paper analyzes the phenomenon of color adaptation and provides a method of color appearance matching through modeling to achieve color appearance matching under variable observation conditions. Based on the chromatic adaptation transformation, a chromatic appearance model is given, which can predict the corresponding color and also predict the chromatic appearance properties of color stimuli under given observation conditions. In addition, this paper constructs an intelligent motion pattern recognition system combined with artificial visual neural network. The experimental results show that the motion pattern recognition system based on artificial visual neural network can accurately identify the motion pattern category.

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Stubbs, Alexander L., et Christopher W. Stubbs. « Spectral discrimination in color blind animals via chromatic aberration and pupil shape ». Proceedings of the National Academy of Sciences 113, n^o 29 (5 juillet 2016) : 8206–11. http://dx.doi.org/10.1073/pnas.1524578113.

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We present a mechanism by which organisms with only a single photoreceptor, which have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide “color-blind” animals with a way to distinguish colors. As a specific example, we constructed a computer model of the visual system of cephalopods (octopus, squid, and cuttlefish) that have a single unfiltered photoreceptor type. We compute a quantitative image quality budget for this visual system and show how chromatic blurring dominates the visual acuity in these animals in shallow water. We quantitatively show, through numerical simulations, how chromatic aberration can be exploited to obtain spectral information, especially through nonaxial pupils that are characteristic of coleoid cephalopods. We have also assessed the inherent ambiguity between range and color that is a consequence of the chromatic variation of best focus with wavelength. This proposed mechanism is consistent with the extensive suite of visual/behavioral and physiological data that has been obtained from cephalopod studies and offers a possible solution to the apparent paradox of vivid chromatic behaviors in color blind animals. Moreover, this proposed mechanism has potential applicability in organisms with limited photoreceptor complements, such as spiders and dolphins.

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Yamamoto, Kyosuke, Yoshitsugu Kimura, Takashi Togami, Yosuke Yoshioka, Atsushi Hashimoto et Takaharu Kameoka. « A Chromatic Image Analysis System Using Content-Based Image Retrieval ». Agricultural Information Research 20, n^o 4 (2011) : 139–47. http://dx.doi.org/10.3173/air.20.139.

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