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.

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.

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.

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.

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).

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 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.

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.

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 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.

An optical model of bright pupil effect based on Chinese human eye model is presented. The effects of the incident rays angle and the size of pupil on bright pupil effect are analyzed theoretically. For the incident rays with 5°–15° field of view, the spot diagram of emergent light is also presented. With the pupil diameters of 3–8 mm, the intensity distributions formed by emergent light are calculated. The optical model of bright pupil effect based on Chinese human eye provides a suitable model for the related further research studies and applications on bright pupil effect with Chinese eye.

Head-up displays (HUDs) enable a pilot to manage aircraft activities by facilitating simultaneous access to the flight instrument data and to the outside scene. However, HUDs can also distract a pilot. This study shows that HUD luminance non-uniformity may force inappropriate distribution of attention between the events shown on HUD symbology and the outside scene because of the resultant differential contrast in the display area. Results of statistical analysis demonstrate considerable effects of HUD image luminance and ambient luminance, as well as their interaction, on the detection of events displayed on an HUD and the outside scene.

A psychophysical experiment is carried out to evaluate the color difference between pairs of color digital images and their modulated versions, which are displayed on a professional liquid crystal display (LCD) monitor, using the category judgment method. The modulated images for six original images are generated with variations in five attributes, namely, lightness, chroma, hue, resolution, and sharpness, considering both their chromatic and spatial characteristics. Several color difference evaluation methods, namely, CIELAB, CIEDE2 000, CAM02-UCS, S-CIELAB, and iCAM, are compared based on the experimental data. The results demonstrate that the performance of iCAM is the best for predicting image color difference.

In this study, 15 parameters representing textile properties are evaluated by the psychophysical method of categorical judgment with samples presented either in a light booth or on a display to investigate human visual perception based on the textural features of textiles. Visual perceptions of textiles can be expressed by the properties of regularity, smoothness, and warmth, which respectively explain the geometric placement rules of primitive elements, depth information, and emotion of textiles. Textiles with large primitive elements have high regularity and coarseness, whereas textiles with subtle primitive elements exhibit randomness and smoothness. Texture analysis results of the surface samples coincide well with those of display samples.

A Projector-camera (Procam) system is an inexpensive, household, controllable system that can be used to eliminate inter-reflection existing in the measurement. We propose an estimation method for spectral reflectance that uses the Procam system. The method recovers reflectance from the training set constructed by a known reflectance and the corresponding 9D color-mixing matrix. Experiment results show that our method performs well with 9D response, and the local weighted training set based on Mahalanobis metric can enhance the accuracy of result efficiently.

To improve the color reproduction accuracy of image among digital devices in spectral color reproduction, a novel profile connection space is proposed. The profile connection space is composed of three sets of tristimulus determined by the principal components of typical illuminants and CIE1931XYZ standard colorimetric observer. The spectral reflectance of three common used atlases is transformed to three deformations of the profile connection space, and then transformed back to the spectral reflectance. The color difference between the original and transformed reflectance are very small for the common used illuminants, which indicates that the profile connection space is a good candidate for spectral color reproduction.

A Chinese skin colour database is established based on measurements taken from nine bodies areas of 202 Chinese individuals to move towards accurate skin colour reproduction. The colour appearance of each skin point is predicted, and a comprehensive colour gamut for Chinese skin is determined. A consistent colour shift between facial and arm colours is identified, in which facial colour tends to be more reddish, more colourful, and darker than arm colour. Moreover, Chinese females are found to have lighter, paler, and more yellowish skin than Chinese males. Variations in Chinese skin colour are quantified, and body area differences and gender differences are shown to have significant effects on Chinese skin colour.

A psychophysical experiment is performed on two large-size liquid crystal displays under three viewing conditions to assess perceptual contrast. Based on the visual data, the performance of CIECAM02 in predicting perceptual contrast under different viewing conditions is tested and compared with other models by F-test. Results show that the perceptual contrast models in the form of Weber contrast using CIECAM02 brightness Q agreed better with the contrast perception of human visual system compared to the models using luminance, CIELAB lightness L¤, and CIECAM02 lightness J.

Seven color separation criteria are evaluated and compared for multi-ink printer characterization, which is a union of five 3-ink and six 4-ink cellular Yule-Nielsen spectral Neugebauer (CYNSN) submodels. In the experimental stage, testing reflectances from printing samples and Munsell color samples are employed. The results show that the prediction and actual accuracy of all the seven selection criteria are approximately the same for printing samples. As for the Munsell samples, the combE00 &MI outperforms other selection criteria because it combines one color difference with two metamerism indices, which are important for the heterogeneous samples during prediction.

A camera-based model is established to predict the total difference for samples of metallic panels with effect coatings under directional illumination, and the testing results indicate that the model can precisely predict the total difference between samples with metallic coatings with satisfactory consistency to the visual data. Due to the limited amount of testing samples, the model performance should be further developed by increasing the training and testing samples.

Conventional printer characterisation models are generally based on the assumption that the densities of primary colours are additive. However, additivity failure frequently occurs in practice. We propose a novel grey component replacement (GCR) method based on the spectral density sub-additivity equations in this letter for spectral characterisation of a 4-ink colour printer. The method effectively correct the error caused by additivity failure. Real high-quality hardcopy samples are produced as evidence of the feasibility of the proposed method and to evaluate the model performance. Finally, the GCR model for characterising colour printer with high spectral and colorimetric prediction accuracy is established.

Clromatic sensitivity along the protan, deutan, and tritan lines and the loci of the unique hues (red, green, yellow, blue) for a very large sample (n = 185) of colour-normal observers ranging from 18 to 75 years of age are assessed. Visual judgments are obtained under normal viewing conditions using colour patches on self-luminous display under controlled adaptation conditions. Trivector discrimination thresholds show an increase as a function of age along the protan, deutan, and tritan axes, with the largest increase present along the tritan line, less pronounced shifts in unique hue settings are also observed. Based on the chromatic (protan, deutan, tritan) thresholds and using scaled cone signals, we predict the unique hue changes with ageing. A dependency on age for unique red and unique yellow for predicted hue angle is found. We conclude that the chromatic sensitivity deteriorates significantly with age, whereas the appearance of unique hues is much less affected, remaining almost constant despite the known changes in the ocular media.