Journals > > Topics > Vision, Color, and Visual Optics
Vision, Color, and Visual Optics|22 Article(s)
The von Kries chromatic adaptation transform and its generalization
Cheng Gao, Zhifeng Wang, Yang Xu, Manuel Melgosa, Kaida Xiao, Michael H. Brill, and Changjun Li
Most viable modern chromatic adaptation transforms (CATs), such as CAT16 and CAT02, can trace their roots both conceptually and mathematically to a simple model formulated from the hypotheses of Johannes von Kries in 1902, known as the von Kries transform/model. However, while the von Kries transform satisfies the properties of symmetry and transitivity, most modern CATs do not satisfy these two important properties. In this Letter, we propose a generalized von Kries transform, which satisfies the symmetry and transitivity properties in addition to improving the fit to most available experimental visual datasets on corresponding colors. Most viable modern chromatic adaptation transforms (CATs), such as CAT16 and CAT02, can trace their roots both conceptually and mathematically to a simple model formulated from the hypotheses of Johannes von Kries in 1902, known as the von Kries transform/model. However, while the von Kries transform satisfies the properties of symmetry and transitivity, most modern CATs do not satisfy these two important properties. In this Letter, we propose a generalized von Kries transform, which satisfies the symmetry and transitivity properties in addition to improving the fit to most available experimental visual datasets on corresponding colors.
Chinese Optics Letters
- Publication Date: Mar. 10, 2020
- Vol. 18, Issue 3, 033301 (2020)
Design of double-zone aspheric diffractive intraocular lens with extended depth of focus|On the Cover
Yayan Bian, Yongji Liu, and Lai Jiang
A double-zone aspheric diffractive intraocular lens (IOL) was designed and manufactured aiming to regain a continuous range of clear vision for pseudophakic presbyopia. After obtaining the IOL structure parameters through optimization based on an aphakic model eye, its imaging performances were analyzed in the model eye. The modulation transfer function at 50 cycles/mm remained above 0.29 within ±5° field of view for object distance ranging from 6 to 0.66 m. In addition, the imaging qualities are robust for pupil changes, polychromatic light, and different corneal asphericities. The manufactured IOL exhibits the ability to extend depth of focus. A double-zone aspheric diffractive intraocular lens (IOL) was designed and manufactured aiming to regain a continuous range of clear vision for pseudophakic presbyopia. After obtaining the IOL structure parameters through optimization based on an aphakic model eye, its imaging performances were analyzed in the model eye. The modulation transfer function at 50 cycles/mm remained above 0.29 within ±5° field of view for object distance ranging from 6 to 0.66 m. In addition, the imaging qualities are robust for pupil changes, polychromatic light, and different corneal asphericities. The manufactured IOL exhibits the ability to extend depth of focus.
Chinese Optics Letters
- Publication Date: Sep. 10, 2018
- Vol. 16, Issue 9, 093301 (2018)
Objective visual performance evaluation with visual evoked potential measurements based on an adaptive optics system
Yanrong Yang, Junlei Zhao, Haoxin Zhao, Fei Xiao, Jiaxin Xie, Tiejun Liu, and Yun Dai
An objective visual performance evaluation with visual evoked potential (VEP) measurements was first integrated into an adaptive optics (AO) system. The optical and neural limits to vision can be bypassed through this system. Visual performance can be measured electrophysiologically with VEP, which reflects the objective function from the retina to the primary visual cortex. The VEP measurements without and with AO correction were preliminarily carried out using this system, demonstrating the great potential of this system in the objective visual performance evaluation. The new system will provide the necessary technique and equipment support for the further study of human visual function. An objective visual performance evaluation with visual evoked potential (VEP) measurements was first integrated into an adaptive optics (AO) system. The optical and neural limits to vision can be bypassed through this system. Visual performance can be measured electrophysiologically with VEP, which reflects the objective function from the retina to the primary visual cortex. The VEP measurements without and with AO correction were preliminarily carried out using this system, demonstrating the great potential of this system in the objective visual performance evaluation. The new system will provide the necessary technique and equipment support for the further study of human visual function.
Chinese Optics Letters
- Publication Date: May. 10, 2018
- Vol. 16, Issue 5, 053301 (2018)
Customized design and efficient machining of astigmatism-minimized progressive addition lens
Yiyu Li, Wei Huang, Haihua Feng, and Jiaojie Chen
Astigmatism is inevitable and inherent to progressive addition lenses (PALs), which are typically distributed in the lateral areas on both sides of the progressive corridor. In this study, we took into account the spectacle frame for the customized freeform PAL design with the variational-difference numerical approach. The PAL surface with minimized astigmatism, approximately equal to 84% of the added power, was numerically resolved without expending the zone for clear vision. We validated our approach by experimentally demonstrating the procedure from tool path generation to surface power measurement, thus providing an efficient solution to the personalization of astigmatism-minimized PAL design and manufacture. Astigmatism is inevitable and inherent to progressive addition lenses (PALs), which are typically distributed in the lateral areas on both sides of the progressive corridor. In this study, we took into account the spectacle frame for the customized freeform PAL design with the variational-difference numerical approach. The PAL surface with minimized astigmatism, approximately equal to 84% of the added power, was numerically resolved without expending the zone for clear vision. We validated our approach by experimentally demonstrating the procedure from tool path generation to surface power measurement, thus providing an efficient solution to the personalization of astigmatism-minimized PAL design and manufacture.
Chinese Optics Letters
- Publication Date: Nov. 10, 2018
- Vol. 16, Issue 11, 113302 (2018)
Objective quantification of chromatic aberration across the visual field of the human eye
Yangchun Deng, Junlei Zhao, Yun Dai, and Yudong Zhang
A simple and straightforward method to objectively measure the transverse chromatic aberration (TCA) at horizontal field angles out to ±10° from the visual axis of the human eye was proposed. Longitudinal chromatic aberration (LCA) was also measured across the visual field. The TCA of a human eye was obtained by deviation of the point spread function (PSF) images. LCA was calculated from the Zernike defocus. The average TCA changing with eccentricity was 0.162 arcmin/degree between 639 nm and 795 nm wavelengths. Near the optic axis of the eye, the average LCA was 0.37 ± 0.02 D, and it increased slightly with eccentricity (up to 0.54 ± 0.02 D). A simple and straightforward method to objectively measure the transverse chromatic aberration (TCA) at horizontal field angles out to ±10° from the visual axis of the human eye was proposed. Longitudinal chromatic aberration (LCA) was also measured across the visual field. The TCA of a human eye was obtained by deviation of the point spread function (PSF) images. LCA was calculated from the Zernike defocus. The average TCA changing with eccentricity was 0.162 arcmin/degree between 639 nm and 795 nm wavelengths. Near the optic axis of the eye, the average LCA was 0.37 ± 0.02 D, and it increased slightly with eccentricity (up to 0.54 ± 0.02 D).
Chinese Optics Letters
- Publication Date: Nov. 10, 2018
- Vol. 16, Issue 11, 113301 (2018)
Color correction for tiled projection with irregularly shaped, overlapping region
Feng Chen, Yue Liu, and Tao Yang
In this Letter, a new, constrained color-matching algorithm that removes the color variations is presented, in which all the color gamut of the projectors is mapped into a common gamut that can be produced by all the devices in the system. The smoothness constraints on the difference between two adjacent pixels are taken into account to calculate the luminance attenuation map of each pixel in the overlapping region to achieve luminance seamlessness. The experimental results demonstrate the validity and superiority of this correction algorithm. In this Letter, a new, constrained color-matching algorithm that removes the color variations is presented, in which all the color gamut of the projectors is mapped into a common gamut that can be produced by all the devices in the system. The smoothness constraints on the difference between two adjacent pixels are taken into account to calculate the luminance attenuation map of each pixel in the overlapping region to achieve luminance seamlessness. The experimental results demonstrate the validity and superiority of this correction algorithm.
Chinese Optics Letters
- Publication Date: Sep. 10, 2015
- Vol. 13, Issue 9, 093301 (2015)
Chromaticity of white sensation for LED lighting
Qing Wang, Haisong Xu, and Jianqi Cai
In this work, a psychophysical experiment is implemented to assess the white sensation of light-emitting diode (LED) lighting in illuminant mode via a categorical judgment method by a panel of 10 observers. The visual data indicates that the higher values of white sensation estimations locate near the Planckian locus within a correlated color temperature (CCT) range of 5000–9000 K. A model of white sensation for LED lighting in illuminant mode is proposed, from which the predicted maximal white sensation locates near the Planckian locus with a CCT of 6622 K, and the 95% white sensation covers a narrow two-dimensional region. In this work, a psychophysical experiment is implemented to assess the white sensation of light-emitting diode (LED) lighting in illuminant mode via a categorical judgment method by a panel of 10 observers. The visual data indicates that the higher values of white sensation estimations locate near the Planckian locus within a correlated color temperature (CCT) range of 5000–9000 K. A model of white sensation for LED lighting in illuminant mode is proposed, from which the predicted maximal white sensation locates near the Planckian locus with a CCT of 6622 K, and the 95% white sensation covers a narrow two-dimensional region.
Chinese Optics Letters
- Publication Date: Jul. 10, 2015
- Vol. 13, Issue 7, 073301 (2015)
Integral colorimeter based on compound LED illumination
Kun Yuan, Huimin Yan, and Shangzhong Jin
Traditional integral colorimeters use tungsten–halogen or xenon lamps for illumination, as well as correcting filters to make the instrument's spectral response meet the Luther condition. This structure causes the instruments to have relatively higher error and poor repeatability. Thus, this letter proposes a new measurement design that uses compound LEDs as the instrument's measurement light source. The new design adjusts the instrument's spectral response by modifying the spectra of the compound LEDs. A compound LED light source is designed for integral colorimeters, and an experiment is conducted to evaluate the performance of the integral colorimeter. Experiments show that the design effectively reduces the error of integral colorimeters. Traditional integral colorimeters use tungsten–halogen or xenon lamps for illumination, as well as correcting filters to make the instrument's spectral response meet the Luther condition. This structure causes the instruments to have relatively higher error and poor repeatability. Thus, this letter proposes a new measurement design that uses compound LEDs as the instrument's measurement light source. The new design adjusts the instrument's spectral response by modifying the spectra of the compound LEDs. A compound LED light source is designed for integral colorimeters, and an experiment is conducted to evaluate the performance of the integral colorimeter. Experiments show that the design effectively reduces the error of integral colorimeters.
Chinese Optics Letters
- Publication Date: Jan. 27, 2014
- Vol. 12, Issue 2, 023302 (2014)
Evaluation of small suprathreshold color differences under different background colors
Zhehong Wang, and Haisong Xu
A psychophysical experiment under constant stimuli is conducted on a CRT display to measure the visual suprathreshold color differences for five color centers recommended by CIE under the same five background colors. The performances of four CIELAB-based, three CIECAM02-based, and two OSA-UCS-based formulas are tested. Detailed analysis results indicate the existence of chromatic crispening effect. CIEDE2000 performs best for the gray center and gray background, whereas CAM02-LCD and CAM02-UCS have the best performance for non-neutral backgrounds. CAM02-LCD significantly outperforms all other formulas for all color centers under all background colors. A psychophysical experiment under constant stimuli is conducted on a CRT display to measure the visual suprathreshold color differences for five color centers recommended by CIE under the same five background colors. The performances of four CIELAB-based, three CIECAM02-based, and two OSA-UCS-based formulas are tested. Detailed analysis results indicate the existence of chromatic crispening effect. CIEDE2000 performs best for the gray center and gray background, whereas CAM02-LCD and CAM02-UCS have the best performance for non-neutral backgrounds. CAM02-LCD significantly outperforms all other formulas for all color centers under all background colors.
Chinese Optics Letters
- Publication Date: Jan. 23, 2014
- Vol. 12, Issue 2, 023301 (2014)
Acquiring multi-spectral images by digital still cameras based on XYZLMS interim connection space
Xiandou Zhang, Qiang Wang, Genfu Yang, and Mengmeng Wang
A method based on the XYZLMS interim connection space is proposed to accurately acquire the multi-spectral images by digital still cameras. The XYZLMS values are firstly predicted from RGB values by polynomial model with local training samples and then spectral reflectance is constructed from XYZLMS values by pseudo-inverse method. An experiment is implemented for multi-spectral image acquisition based on a commercial digital still camera. The results indicate that multi-spectral images can be accurately acquired except the very dark colors. A method based on the XYZLMS interim connection space is proposed to accurately acquire the multi-spectral images by digital still cameras. The XYZLMS values are firstly predicted from RGB values by polynomial model with local training samples and then spectral reflectance is constructed from XYZLMS values by pseudo-inverse method. An experiment is implemented for multi-spectral image acquisition based on a commercial digital still camera. The results indicate that multi-spectral images can be accurately acquired except the very dark colors.
Chinese Optics Letters
- Publication Date: Oct. 24, 2014
- Vol. 12, Issue 11, 113302 (2014)
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