Qiang Liu

Wuhan University | WHU · School of Printing and Packaging

A novel metric named Gamut Volume Index (GVI) is proposed for evaluating the colour preference of lighting. This metric is based on the absolute gamut volume of optimized colour samples. The optimal colour set of the proposed metric was obtained by optimizing the weighted average correlation between the metric predictions and the subjective ratings...

In this work, the correlation between the whiteness of lighting and the preference for the colour of lighting was comprehensively investigated based on four psychophysical studies. Different sets of experimental light sources, two of constant correlated colour temperatures (CCT) and two of different CCTs were adopted to illuminate multiple experime...

On the topic of color preference of lighting, it is commonly believed that the neutral interior of a light booth has minimum impact on the color perception of the experimental object. Meanwhile, agreement has not been reached on which objects should be placed in the booth. In this study, based on a meta-analysis of eight groups of psychophysical da...

In this Letter, we propose a combined metric for quantifying the color discrimination capability of white light sources. This metric is based on considerations of human visual adaptation to daylight chromaticities, as well as on the concerns of the huge spectral diversity of modern light sources. Two existing metrics, ${{{S}}_{\rm{neutral}}}$ S n e...

Colour preference is a critical dimension for describing the colour quality of lighting and numerous metrics have been proposed. However, due to the variation amongst psychophysical studies, consensus has not been reached on the best approach to quantify colour preference. In this study, 25 typical colour quality metrics were comprehensively tested...

Display-based simulation has been widely adopted across various research fields, yet the visual consistency between this technique and real scene observation remains inadequately demonstrated. This study aimed to assess the feasibility of quantifying the color rendition performance of white light sources using display simulation. We examined the vi...

Two studies were conducted to investigate the impact of fresh pork display lamps on consumers’ sensory responses to pork products. In the first experiment, 63 participants were asked to evaluate pork products with different degrees of freshness under four fresh pork display lights and two LED lights. In the other experiment, 30 subjects participate...

The influence of correlated color temperature (CCT) on the color quality of light sources has been extensively investigated. However, the limitations and nonuniformity associated with the CCT parameter have hindered its effectiveness in lighting designs and applications. To explore the color perception and visual memory of light sources with varyin...

Lipstick is one of the most commonly used cosmetics, which is closely associated with female attractiveness and influences people’s perception and behavior. This study aimed to investigate the impact of light sources, lipstick colors, as well as gender on the subjective assessment of lipstick color products from the prospective of color preference,...

Colorimetric characterization is the basis of color information management in color imaging systems. In this paper, we propose a colorimetric characterization method based on kernel partial least squares (KPLS) for color imaging systems. This method takes the kernel function expansion of the three-channel response values (RGB) in the device-depende...

Psychophysical experiment is the most straightforward and reliable way to investigate the impact of lighting on visual colour perception. In this study, a series of experiments were conducted in order to investigate the impact of experimental setting and protocol on the obtained conclusions in visual tests regarding human preference on object colou...

In this study, three psychophysical approaches that quantify the color discrimination capability of white light sources were systematically compared. A total of 11 light sources, five of 5500 K and six of 3000 K, were tested in two groups using three typical psychophysical methods including the Farnsworth‐Munsell100 Hue Test, real objects observati...

This study aimed to investigate whether the illuminance level and correlated colour temperature of light sources, as well as the viewing background, influenced the human visual assessment and purchase intention for bread and cakes. The impact of gender difference, hunger status and many other personal factors on consumption behaviour was also explo...

Color discrimination is a crucial dimension for the visual assessment of white light sources. In this Letter, we took full advantage of data comparability among Farnsworth–Munsell 100 Hue (FM-100) color vision tests and modified our recent proposed color discrimination metric [Opt. Lett. 45, 6062 (2020)10.1364/OL.400422] to make it effective in qua...

In this paper, the authors discuss a hot and disputable topic in colour quality evaluation for lighting. During the past years, it is quite common to investigate the impact of CCT and Duv on colour preference of lighting. Theoretically speaking, the conclusions of those work are not perfectly rigorous. First, there are numerous SPDs corresponding t...

An improved spectral reflectance estimation method was developed to transform captured RGB images to spectral reflectance. The novelty of our method is an iteratively reweighted regulated model that combines polynomial expansion signals, which was developed for spectral reflectance estimation, and a cross-polarized imaging system, which is used to...

For digital camera‐based spectra recovery, the spectral reflectance of the object being imaged always needs to be accurately recovered using training samples from available database. Considering the heavy workload when using all samples in database as training samples in practice, a new representative samples selection method is proposed for effici...

Recent studies reported a series of neutral loci for white lighting, which showed significant differences when the correlated colour temperature was greater than 4000 K. Several were located above the Planckian locus while others were located below. In addition, some researchers indicated that the whiteness of lighting correlates with colour prefer...

Two psychophysical experiments were conducted to evaluate the performance of grayscale image colorization models, and to verify the objective image quality metrics adopted in grayscale image colorization. Twenty representative grayscale images were colourized by four colorization models and three typical metrics, root mean square error (RMSE), peak...

The aim of this study was to explore the interactive effect of Illuminance (E) and Correlated Colour Temperature (CCT) on the visual appreciation of the colour rendition of lighting (termed as colour preference), as well as on a newly defined visual attribute termed the degree of white light sensation, which describes the Chinese understanding on a...

In this field study, a series of psychophysical tests were conducted to investigate the impact of indoor lighting on students' visual perception and cognitive performance. A typical classroom of Wuhan University (China) was fitted with tubular light-emitting diode (LED) sources and LED panel sources in two experiments, respectively. Under the two l...

Gender difference has been widely reported in many research fields. However, in the topic of colour preference of lighting, such an issue has not aroused much attention. In this study, therefore, three groups of visual experiments with different illuminance (E) levels (50 lx, 200 lx, 600 lx) were conducted which investigated the preferred correlate...

Many studies now use coloured objects when discussing lighting colour preference, but rarely involve black and white objects. In this study, nine CCTs were adopted to illuminate three groups of black and white objects (a group of black and white birds, a group of black and white statues and four black and white photographs). Thirty observers, 16 ma...

Nowadays, many studies are trying to propose a measure for characterizing the colour discrimination of human vision. Our previous work conducted three sets of colour discrimination experiments using the Farnsworth -Munsell (FM) 100 Hue Test under lighting conditions with different correlated colour temperatures, illumination levels and Duv values....

Now many studies discuss the preferred correlated colour temperature (CCT) as well as the validity of colour quality metrics. However, most of them were implemented under a constant illuminance (E) level. In this study, three E levels (50, 200, 600 lx) and three CCT levels (3500, 5000, 6500 K) were adopted to illuminate six single-coloured decorati...

A series of psychophysical experiments have been conducted to investigate the effect of light sources on the color appearance of Chinese bronzeware. Three groups of 30 observers were asked to evaluate a set of Chinese bronzeware under different light sources in three paired-comparison experiments—one group of observers for each experiment. The visu...

In the digital printing process, reliable colour reproduction is commonly achieved by printer characterisation, which defines the correspondence between the input device control values and the output colour information. The cellular Yule–Nielsen spectral Neugebauer model, together with its variants, is widely adopted in this topic because of its su...

Our previous work revealed that, compared with other correlated colour temperatures (CCTs), a light source of 5500 K could arouse the strongest colour preference perception for blue jeans and provide the best colour discrimination capability for blue colours. In this study, we further investigated the impact of light sources on colour preference an...

In this work, the correlation between the perceived whiteness of lighting and the corresponding colour preference of observers was comprehensively investigated based on the data of 19 groups of experiments collected from 14 studies. The dataset included 13 experiments with constant correlated colour temperature and 6 experiments with multiple corre...

In this study, two psychophysical experiments, one on colour preference and the other on colour discrimination, were conducted. To investigate the colour preference for blue jeans, 27 subjects with normal colour vision were asked to rate their visual appreciation of seven pairs of jeans with a colour gradient pattern. Nine LEDs, with uniformly samp...

The colour quality of lighting is usually assessed by psychophysical studies and the conclusions of those works are always dependent on the corresponding experimental settings. In this contribution, the meta-analysis approach for this topic is highlighted, which could derive a robust estimate closest to the truth and thus draw a more plausible conc...

The Updating of spectral printer characterization model aims at maintaining the accuracy of the existed characterization model by certain corrective algorithm when the printing substrate or ink cartidge is changed. In this study, a novel method was proposed to improve the modification performance for current printer characterization model, which de...

Do people prefer whiter light ? To investigate this topic, the experimental data of 14 psychophysical studies regarding colour preference of lighting were collected and the correlation between white lighting and colour preference was calculated. The derived data set contained 24 metameric lighting scenarios with low correlated colour temperatures (...

Existing studies have shown that a linear combination of some color quality metrics can be used to characterize observers’ color preference of light source. In order to study the correlation between metrics and color preference, nine kinds of LED light sources with different correlated color temperature were selected, and the subjective evaluation...

The individual color preference plays an important role in visual experience. Therefore, a rigorous psychophysical experiment was carried out to investigate the influence of the individual color preference on lighting preference. 45 observers (age from 19–25) were selected from 318 valid questionnaires including three categories of people (15 stude...

Existing studies used different scales to evaluate the quality of LED lighting by psychophysics experiments, which viewed specific objects. It is believed that for universal lighting, diverse objects are needed to evaluate color quality. In order to produce a suitable factors space to evaluate the quality of universal lighting, a psychophysics expe...

In our recent work, the colour preference of several LED white lights with different correlated colour temperatures (CCTs) was investigated with a wide selection of objects. The results highlighted the dominant effect of light itself on the colour preference of lighting. In this study, we similarly implemented two psychophysical experiments with th...

1st Museum Lighting Symposium

Colour preference for lighting is generally influenced by three kinds of contextual factors, the light, the object and the observer. In this study, a series of psychophysical experiments were conducted to investigate and compare the effect of certain factors on colour preference, including spectral power distribution of light, lighting application,...

This paper proposes an improved reflectance reconstruction method by adaptively selecting training samples. Modified Principal Component Analysis estimation was proposed by orthogonal regression considering the system noise; deriving the optimum number of training samples by BP-Adaboost neural network; and grouping the representative samples togeth...

Due to the variety of the illuminant-observer devices and different color media, people need to transform the color recorded in a source media into correlated color in another target media. In order to keep the color consistency in different media and achieve high color transform accuracy for digital color reproduction, a polynomial fitting approac...

Different geographical environment affects the forming and development of several aspects of race, customs and culture, which directly lead to the diverse preferences to colors and LED light color rendering. Chinese people’s cognition features of colors and LED light color rendering, share great similarity, and meanwhile bear many differences that...

To improve the transform accuracy of colorimetric values for digital colour reproduction, a neural network approach based on a large-scale spectral dataset was proposed. The presented dataset exhibited a particularly wide colour gamut and was partitioned into 12 subsets according to dominant wavelength and excitation purity. In each subset, the non...

The Chinese calligraphy is a unique art of traditional Chinese culture. The core of color preference for Chinese calligraphy is figural preference, which is a special kind of color combination preference. Currently, the exhibition of calligraphy is always lack of scientific basis in the aspect of color science. In this research, the influence of li...

The existing methods - such as sieving, microscope, light scattering, sedimentation, and electrical induction for pigment size detection - require sampling or scattering the mineral pigments, which will inevitably cause damage to the films painted by mineral pigments. A new detection method based on run length texture analysis is proposed to nondes...

The color of the LED smart light is tunable by its inner equipped micro-processing systems. Therefore, it could provide significant improvement for the smart lighting conditions, such as museum lighting and home lighting. At present, the limitation of the current lighting blending technology remarkably affects the application of smart lighting tech...

Spectral data or chrominance data acquired with color measurement device is able to objectively characterize the true color information of the object. As to the measuring target that without direct contact with the measuring instrument, it needs to adopt the non-contact color measurement method to obtain the color information. The spectral irradian...

This paper proposed two weight functions based on principal component analysis (PCA) to reserve more colorimetric information in spectral data compression process. One weight function consisted of the CIE XYZ color-matching functions representing the characteristic of the human visual system, while another was made up of the CIE XYZ color-matching...

Noninvasive examination methods of chemical composition and particle size are presented here based on visible spectroscopy to achieve the identification and recording of mineral pigments used on ancient wall paintings. The normalized spectral curve, slope and curvature extracted from visible spectral reflectance are combined with adjustable weighti...

The existing standard colorcharts or databases always have large sample size and suffer from color redundancy, which inevitability leads to a time-consuming process for practical spectral imaging. In order to resolve this problem, an optimal training sample selection method was proposed whose main idea was choosing the most effective samples from e...

The existing standard colorcharts or databases always have large sample size and suffer from color redundancy, which inevitability leads to a time-consuming process for practical spectral imaging. In order to resolve this problem, an optimal training sample selection method was proposed whose main idea was choosing the most effective samples from e...

The composition of training samples set is an important influence factor of spectral reflectance reconstruction process. Representative color samples selection for learning-based spectral reflectance reconstruction is discussed in this paper. A method based on Principal Component Analysis (PCA) is proposed to perform sample selection. First of all,...

In cross-media digital color imaging workflow, the colorimetric information transform among various digital medias always suffers from large transform errors, due to the difference among the lighting illuminants and the digital devices. Colorimetric correction aims at avoiding the colorimetric transform mismatch and thus improving the color transfo...

Reflective spectra in a multispectral image can objectively and originally represent color information due to their high dimensionality, illuminant independent and device independent. Aiming to the problem of loss of spectral information when the spectral data reconstructed from three-dimensional colorimetric data in the trichromatic camera-based s...

The construction of spectral discoloration model, based on aging test and simulating degradation experiment, was proposed to detect the aging degree of red lead pigment in ancient murals and to reproduce the spectral data supporting digital restoration of the ancient murals. The degradation process of red lead pigment under the aging test condition...

Printing engineering is an interdisciplinary specialty which involves a lot of intercross subjects such as optical engineering, information engineering, material science and engineering, mechanical engineering, control science and engineering, computer engineering, software engineering and so on. Nowadays, as those subjects progress, the content of...

Digitization of cultural heritage protection has received considerable attention in heritage studies and spectral imaging technology has been playing an important role in this research. This article aims to study the technique of selecting optimal filter set to obtain ancient murals spectral image with high spectral and colorimetric accuracy based...

Five representative correlated color temperature were selected through intelligent-tunable LED light source, and 42 students(21 female,21 male) of normal color vision were examed with the Farnsworth-Munsell 100-Hue Test (FM 100 Hue Test), in order to analyze the impact of correlated color temperature of LED light source on color discrimination. The...

To resolve the image shift problem of visible broadband spectral imaging in the field of color and imaging science, an improved image registration method based on Scale-invariant feature transforms (SIFT) algorithm is proposed. Firstly, the feature points are extracted by the SIFT algorithm. Secondly the feature points are matched by the nearestnei...

Color constancy is a key metric for evaluating the color reproduction performance. This contribution proposed a color constancy based spectral separation method for muti-ink printers from the prospect of color perception. Basing on our previously developped spectral printer modeling workflow, a novel color constancy based spectral separation method...