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The aim of this works is developing a software system that uses machine learning and computer vision to reconstruct a real indoor environment into a 3D model for use in interior design. The project involves assembling a robust computer vision system, which will require the use of deep learning and image processing techniques. The software will take a set of photos of a room as input, apply camera calibration algorithms to find the correct camera parameters, build a reconstruction of the room in 3D, apply instance segmentation to locate different elements in the room, generate 3D models of these objects, and finally, obtain the correct material and texture for each element of the 3D reconstruction. The project requires dividing the work into different sub-jobs, with each requiring its own research to achieve the most satisfactory solution, taking into account aspects such as efficiency, time, and computer resources.

To improve the accuracy of color reproduction for camouflage printing, a new color matching method, named monitor-paper-fabric, was proposed by importing color management into textiles, which matched the printing pastes according to the color of the paper card printed by the ink-jet printer after color management. Not like the traditional color matching method, it matched the printing pastes according to the color from computer monitor after color correction. Two color matching methods were analyzed by comparing the color difference. It was found that the “monitor-paper-fabric” color matching method could be considered as a convenient and feasible color matching method. Most color differences between the monitor and the fabric in the camouflage pattern were reduced to lower than 4, except for color blocks 5 and 6. In addition, the color differences of six color blocks between the paper and the fabric were all less than 3.5, and were lower than those between the monitor and the fabric. The color consistency between the paper and the fabric was better than that between the monitor and the fabric.

Numerous human factors need to be considered in the analysis and design of aircraft cockpits. The investigation of cockpit color patterns and the design of matched color schemes are particularly important. In this paper, we propose a fuzzy-logic-based emotional evaluation scheme for color pattern design in aircraft cockpits. Color pattern samples were collected and analyzed to construct a color library for cockpit color matching. Color scheme groups were accordingly redesigned and visualized. Based on fuzzy-set theory, the Kansei engineering model was thus used to evaluate the emotional image of the color schemes, and rank them in terms of priority. A support vector machine was trained to construct a comprehensive intelligent color evaluation system. After training and validating the evaluation model, accurate emotional evaluation of color matching schemes could be achieved. Thus, the proposed system enables the extraction, mapping and evaluation of cockpit color matching schemes, and can be used in color scheme design for other cabins.

Statement of problem During the selection of tooth color, subjective communication with the laboratory and an incorrect color registration technique can lead to a poor color match of a restoration to adjacent teeth and oral structures. Purpose The purpose of this cross-sectional study was to compare color registration and color matching in a young Chilean population with 3 different methods: visual with a shade guide, digital visual with a cross-polarized filter, and instrumental with a spectrophotometer. Material and methods A total of 60 young volunteers were selected for tooth color registration of the maxillary right central incisor by using 3 different methods. Tooth color registration was performed using the CIELab and ΔE coordinate system. Results Significant differences were detected between the coordinates recorded by the visual analog method in comparison with the other 2 methods. In contrast, no significant differences were found between the L∗ and b∗ coordinates of the spectrophotometer and the digital visual method with use of a cross-polarization filter. The ΔE obtained between the visual shade and spectrophotometer was 7.35, and the ΔE between the digital visual method with the use of a cross-polarization filter and the spectrophotometer was 6.12. Conclusions No statistically significant differences were observed in the digital image with the cross-polarization filter and the spectrophotometer in the L∗ and b∗ coordinate of the CIELab system. In contrast, the visual analog method led to large differences with the other methods under study. The ΔE of the digital visual method with the use of cross-polarization filters and the spectrophotometer was 6.2, considered as an acceptable color mismatch (

A good color description starts with the availability of accurate color matching functions (CMFs) or cone fundamentals (CF). Recent work indicates a discrepancy between visual metamers and those calculated using the standard CIE CMFs or other CMF sets, especially for narrowband sources. In the current study, 54 observers (varying in age, gender, ethnicity and eye color) performed a series of achromatic color matching experiments with a 10° stimulus using eight different narrowband primaries under an immersive, perceptually neutral (4673 K) viewing conditions. The reference stimulus was provided by a 70 cd/m² grey (4613 K) card illuminated by a spectrally broadband light source. The results confirm that substantial and significant differences between experimental and calculated metamers exist, particularly when a short wavelength primary (404 nm) is included and especially for the CIE 1931 2° CMFs. It is found that the primary set characterized by the peak wavelengths 636 nm, 521 nm and 447 nm, which are close to those of typical RGB primaries widely used in industry, results in the most stable matching performance across all CMF sets. Finally, in addition to the impact of primary wavelength and CMF set, the potential effect of age, gender, ethnicity and eye color has also been investigated. The effect of age on the color matches is found to be significant and is due to differences in spectral sensitivity of young and old observers with respect to the blue primary; the impact of observer gender, ethnicity and eye color, on color matching accuracy is not significant. ispartof: Leukos vol:18 issue:2 status: Published online

The success of dental treatment is evaluated according to functional and esthetic results. The esthetics of prostheses considered one of the most important parameters of treatment that the patient is interested in. Color matching is an essential procedure to obtain an esthetic prosthesis. Color matching is influenced by several factors, and if not performed properly, it can have unsatisfactory results for both the clinician and the patient. This review discusses color science, factors associated with color perception, and color matching techniques.

Makeup transfer is the task of applying on a source face the makeup style from a reference image. Real-life makeups are diverse and wild, which cover not only color-changing but also patterns, such as stickers, blushes, and jewelries. However, existing works overlooked the latter components and confined makeup transfer to color manipulation, focusing only on light makeup styles. In this work, we propose a holistic makeup transfer framework that can handle all the mentioned makeup components. It consists of an improved color transfer branch and a novel pattern transfer branch to learn all makeup properties, including color, shape, texture, and location. To train and evaluate such a system, we also introduce new makeup datasets for real and synthetic extreme makeup. Experimental results show that our framework achieves the state of the art performance on both light and extreme makeup styles. Code is available at https://github.com/VinAIResearch/CPM.

Plant colors such as ‘green leaf’ and ‘red apple’ are often described based on human sense, even in scientific papers. On the other hand, colors are measured based on colorimetric principles in some papers, especially in the studies of horticultural plants. The science of color measurements (‘colorimetry’) is not included in any of the popular lectures in schools and universities, thus the principles of color measurements would not be understood by most researchers. The present review will overview the principles of colorimetry, and will introduce colorimetric methods which can be used for scientific measurement of plant colors. That is to say, the reflection spectrum of visible light (380–780 nm) is measured at 5-nm intervals on the surface of leaves or petals in ‘Spectrometric Color Measurement’ (SCM). The spectral data is multiplied with RGB or XYZ color matching functions and integrated to obtain RGB or XYZ intensities. Alternatively, approximate RGB values are directly obtained in ‘Photographic Color Measurement’ (PCM). RGB/XYZ intensities are further calculated to obtain ‘hue’, ‘saturation’, and ‘lightness’, the three factors of colors. Colorimetric insights into genetic regulations (such as MYB gene) and physiological regulations (such as alexandrite effect) of plant colors are also described.

Color matching is necessary in the manufacture of colored fiber yarns, and its accuracy is one of the main goals in computer-aided color matching. A limited number of pre-colored fibers are blended to match the target color through predicted recipes. Of the color-prediction models applied in computer-aided color matching, two common ones, Stearns-Noechel and Friele, were selected to be modified to improve the color-prediction accuracy in this paper. The models were modified in three ways, in which the pending parameters in the models were determined through statistical analysis depending on median, wavelength, and components; thus, the Stearns-Noechel model was modified to Stearns-Noechel 1, Stearns-Noechel 2, and Stearns-Noechel 3, and the Friele model was modified to Friele 1, Friele 2, and Friele 3. The six modified models were affirmed through 261 colored fiber yarns prepared from five primary cotton fibers, including two-, three-, four-, and five-primary blends. The prediction results of 261 samples showed that Stearns-Noechel 3 had the highest accuracy among the modified Stearns-Noechel models, especially for four-primary blends with an average color difference of 0.50 Color Measurement Committee (CMC) (2:1) units, whereas Friele 1 had the highest accuracy among the modified Friele models, especially for five-primary blends with an average color difference of 0.46 CMC (2:1) units. These results indicate the modified model Stearns-Noechel 3 can be used in color prediction when there are fewer than five yarn components, and Friele 1 can be used for five components with lower color differences that better meet color-matching requirements in practical production.

The psychophysical description of one of the pillars of color science, the color-matching paradigm, forms the basis of the representation theory of colors. This description entails the weighted integration of a spectral distribution of radiant energy (i.e. a light ray) with three color-matching functions. Here these color-matching functions are conceptualized as a vector-valued measure , which grounds the representation theory of colors in the mathematical frameworks of measure theory and functional analysis. Properties like the convexity and compactness of the tristimulus space follow readily from this color-matching measure model. Notably, the model quite naturally encapsulates metamerism as -equivalence classes of spectral distributions. A subsequent extension of the model to object colors results in similar properties for the object color solid. Also following from this extension is a novel expression for optimal colors. This entails both a comprehensive mathematical formulation of these colors as well as a practical calculation tool for their reflection coefficients.

In this study, the observer variability in a 10° achromatic color matching experiment using systematically different primaries under immersive, perceptually neutral (4673 K) and stable adapted viewing conditions has been investigated for 4 different sets of CIE color matching functions (CMFs). The matching reference was illuminated by a spectrally broadband light source at 70 cd/m² and 4613 K. Fifty-four observers varying in age, gender, ethnicity and eye color participated. The results indicate that certain wavelength regions are more sensitive to generate inter-observer variability, such as when a short wavelength primary (404 nm) was applied. Furthermore, of the primary sets investigated, that with peak-wavelengths (636-521-447 nm) close to the ‘typical’ RGB-primaries widely known and used in industry had the smallest inter-observer variability. In addition to the significant effect of primary set and CMF set, a significant effect of age on matching variability is also found, whereby the change of the blue primary resulted in a substantial difference in dispersion between younger and older observers, likely caused by age-induced yellowing of the lens. Furthermore, different primary sets tend to have a different impact on intra-observer variability than on inter-observer variability. Finally, by comparing the observer variability in the current work with previous studies, the CIE standard deviate observer is found to substantially underestimate the inter-observer variability, especially for the primary sets containing a 404 nm LED. Our observers also tend to have similar to smaller inter-variability than those reported in literature, possibly due to methodological differences. ispartof: Leukos vol:18 issue:2 status: Published online

At the beginning of this century, intrinsically photoreceptive retinal ganglion cells (ipRGCs), new photoreceptors different from cones and rods, were discovered. The aim of this study was to experimentally verify the influence of ipRGCs on the colour reproduction of a display. In the experiment, we performed perceptual colour matching between colour patches and displays. Although colorimetric reproduction of the colour patch was used for the initial image of the display, the colour matching results were largely out of colorimetric colour reproduction. Since this result suggests that ipRGCs may affect colour reproduction of displays, a correction equation that accounts for the influence of ipRGCs was derived. Applying this correction formula improved the results. It is considered possible to accurately display the colour of a real object on a display using a correction equation that accounts for the effect of ipRGCs.

In order to explore the evaluation method of black fabric, this paper uses computer color measurement and color matching technology to select two kinds of polyester knitted white fabrics as raw materials, and utilizes black tubes as standard samples to prepare polyester knitted printed black fabrics. The samples are compared and sorted, and the characteristics of each indicator are analyzed. The results show that it is apt to directly characterize the blackness of polyester knitted printing fabric by DE* value; σ b has a reference significance for determining the end value of blackness within a certain range, but when the reflectance value is very low, the difference between different black fabrics is not very obvious.Gray-scale image-assisted visual evaluation can help observers more objectively evaluate blackness, and can achieve a natural transition from the machine to the human eye, which can reduce visual errors to a certain extent.

Two uniform patches presented on two displays under identical viewing conditions can appear as the same color to one observer but as mismatched colors to another observer. This phenomenon, called observer metamerism (OM), occurs due to individual differences in color matching functions. To avoid its potentially adverse impacts in display calibration and characterization, it is desirable to have a predictive model of OM. In this work, we report the computational results of how to use existing metrics to quantify the potential OM between commercial display pairs and a proposed OM metric that is verified through a psychophysical experiment.

We present a color matching method that, given two different views of the same scene taken by two cameras with unknown settings and unknown internal parameter values, and encoded with unknown non-linear curves, is able to correct the colors of one of the images making it look as if it was captured under the other camera’s settings. Our method is based on treating the in-camera color processing pipeline as a matrix multiplication followed by a non-linearity. This allows us to model a color stabilization transformation among the two shots by estimating several parameters. The method is fast and the results have no spurious colors. It outperforms the state-of-the-art both visually and according to several metrics, and can handle very challenging real-life examples. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 761544 (project HDR4EU) and under grant agreement number 780470 (project SAUCE), and by the Spanish government and FEDER Fund, grant ref. TIN2015-71537-P (MINECO/FEDER,UE).

Indoor lighting environment has an impact on people’s physiology, psychology, cognition, and other aspects, thus affecting people’s work tasks and work efficiency. This paper studies the effects of different color temperature and illumination conditions on cognitive processing depth. The experimental results show that different screen brightness has significant influence on information processing ability under three light environments: dark, white and yellow. The performance of tasks with different processing depth is different under different light environmental conditions. High brightness display and color matching style of night vision interface is recommended in dark environment. High brightness display is recommended in yellow light environment; In white light, medium brightness display and white interface matching style are recommended.

The first half of this chapter reviews the physiology of the eye and vision with focus on the optical structure and formation of the image by the optical system of the human eye. It also explores the illumination features, the subjectivity of color vision and color perception. The last part of the chapter is mostly dedicated to understand the reasons for “color matching” in dental practice and the importance of using perceptibility and acceptability thresholds in Dentistry.

In the digital age, the use of technology in music has become a trend with computers and tablet devices, smartphones and the like. In this study, headphone products as the research object, the most suitable headphone color, pattern and experimental display size. First of all, this study uses 16 psychological test methods to investigate and compare the color reaction products of color technology and color psychology of commercial technology products, and carries out the analysis of semantic differences, making statistical research in black and white to obtain the best color matching color. Finally, use the Likert scale statistics and analysis. The results show that black headphones, minimalist design to get most of the preferences

By capturing a more complete rendition of scene light than standard 2D cameras, light-field technology represents an important step towards closing the gap between live action cinematography and computer graphics. Light-field cameras accomplish this by simultaneously capturing the same scene under different angular configurations, providing directional information that allows for a multitude of post-production effects. Among the practical challenges related to capturing multiple images simultaneously, a very important problem is the fact that the different images do not perfectly match in terms of color, which severely complicates all further processing. In this work we adapt and extend to the light-field scenario a color stabilization method previously proposed for standard multi-camera shoots, and demonstrate experimentally that it provides an improvement over the state-of-the-art techniques for light-field imaging. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 761544 (project HDR4EU) and under grant agreement number 780470 (project SAUCE), and by the Spanish government and FEDER Fund, grant ref. PGC2018-099651-B-I00 (MCIU/AEI/FEDER, UE).

The method of computer color matching gradually replaces the artificial color matching method of giving pigment formula by experience.According to the calculation method of the cie color system, the color of the object can be measured by the instrument.The basic color of computer color matching and its chromaticity value play a decisive role in the efficiency and quality of computer color matching.However, the spectral characteristics and chromaticity values of the basic colors of computer color matching are easily affected by many factors, and the stability of chromaticity values is not strong.This topic intends to study the spectral properties of a large number of pigment samples and calculate the color value, select the red, yellow and blue base pigments that meet the camouflage requirements, and then study the factors that may cause the color chromaticity value of the camouflage. Within the required range, the camouflage base color and its chromaticity value are determined, which lays a foundation for constructing a color database related to the color matching and chromaticity of the computer color matching.

Tiled display systems are widely utilized for digital signage application exceeding the size of a single flat-panel display. Smoothly varying spatial non-uniformity in luminance and color may cause visible difference in the boundary of two adjacent sub-displays. It is necessary to suppress such visible artifacts. Tiled display systems can be installed under various illumination environments and require routine color calibration to compensate for temporal change in display characteristics. This paper presents a simple and cost-effective color calibration method for tiled display systems. Consumer-level digital camera is utilized as a measuring device after the proposed vignetting correction was applied. Experimental results indicate that the proposed color calibration method for tiled display system is quite effective in suppressing the visible artifacts across two adjacent sub-displays.

We investigated observer metamerism under a variety of viewing conditions, in a set of color-matching experiments using displays and printed color samples under specific light sources. A selection was made of light sources with different illuminances, spectral power distributions, and correlated color temperatures, as well as displays with different sets of primaries. A panel of 157 observers with normal color vision and ages between 20 and 59 years old performed 5465 visual color matches around 9 different color centers. The results from the simulated and real experiments were quite different. Specifically, the mean color difference from the mean changed with experimental viewing conditions, ranging from 0.73 to 1.64 CIELAB units (average 0.99 CIELAB units) in simulated experiments, and from 3.12 to 4.03 CIELAB units (average 3.55 CIELAB units) in real experiments. In real experiments, observers’ variability reduced for light sources with high illuminance and high correlated color temperature. Spectral power distributions affected observer metamerism, but the role played by the primaries of the two displays employed was unclear., National Natural Science Foundation of China (NNSFC), 61675029. Ministry of Economy and Competitiveness of the Government of Spain, co-financed by the European Regional Development Fund (ERDF) of the European Union, research project FIS2016-80983-P.

In spectator crowd images, the high number of people, small size and occlusion of body parts, make the body detection task challenging. Due to the similarity in facial features of different people, the variance in head features is less compared to the variation in the body features. Similarly, the visibility of the head in a crowd is more, compared to the visibility of the body. Therefore, the detection of only the head is more successful than the detection of the full body. We show that there exists a relation between head size and location, and the body size and location in the image. Therefore, head size and location can be leveraged to detect full bodies. This paper suggests that due to lack of visibility, more variance in body features, and lack of available training data of occluded bodies, full bodies should not be detected directly in occluded scenes. The proposed strategy is to detect full bodies using information extracted from head detection. Additionally, body detection technique should not be affected by the level of occlusion. Therefore, we propose to use only color matching for body detection. It does not require any explicit training data like CNN based body detection. To evaluate the effectiveness of this strategy, experiments are performed using the S-HOCK spectator crowd dataset. Using partial ground truth head information as the input, full bodies in a dense crowd is detected. Experimental results show that our technique using only head detection and color matching can detect occluded full bodies in a spectator crowd successfully.

Chapter 3 In this Chapter, we explain the basics of colorimetry and introduce the colorimetric tools useful for designing light sources.

In order to solve the problem that the existing adaptive window stereo matching algorithms have insufficient feature extraction in low-texture regions, resulting in low matching accuracy. An adaptive window stereo matching algorithm based on the gradient is proposed. Firstly, the Sobel operator is used to extract the gradient value of each pixel in the image. Then, each pixel is divided into high, medium and low texture regions according to the gradient value. Next, different arm length thresholds are assigned to different region pixels, and matching windows are generated dynamically according to arm length and color threshold. Finally, the pixels closer to the center of the window are given higher weights by generating windows several times. It solves the problem that the stereo matching algorithm can not select a matching window dynamically. Experimental results on Middlebury dataset show that the proposed method improves the matching accuracy by 5.5% compared with the latest adaptive window stereo matching algorithm.

Color vision and spectral sensitivity vary among individuals with normal color vision; thus, for many applications, it is important to measure and correct for an observer’s sensitivity. Full correction would require measuring color and luminance matches and is rarely implemented. However, luminance matches (equiluminance settings) are routinely measured and simple to conduct. We modeled how well an observer’s color matches could be approximated by measuring only luminance sensitivity, since both depend on a common set of factors. We show that lens and macular pigment density and L / M cone ratios alter equiluminance settings in different ways and can therefore be estimated from the settings. In turn, the density variations can account for a large proportion of the normal variation in color matching. Thus, luminance matches may provide a simple method to at least partially predict an observer’s color matches without requiring more complex tasks or equipment.

In the field of virtual game design, in addition to the game content to meet the immersive needs of users, the design in the virtual space is also very important. The color harmony generated by the lights in the virtual space also changes the mindset and cognition of users. They can immerse themselves in the game more quickly, so the colors in the space and the colors produced by the lights can show different atmospheres through different forms of presentation. In the existing researches, interior design color matching is based on simple theories such as hue or contrast color. In terms of space, the consideration is not only for the hue, but also the intensity and configuration of the light. Therefore, by studying the relationship between color and cognition produced by space lighting, this study uses the color effects produced by four different lights as a cognitive difference study, supplemented by an exploration of the trend of color application, and induces the principle of color matching Finally, the differences between the user's perception of the different color matching colors are provided, and finally the reference for the design of the virtual space is provided.

Color is generated by optical properties of the pigments. Colors can be calculated by using color matching functions. Color-measuring apparatus such as colorimeters and digital cameras also provide convenient ways to analyze object colors. Color values are given in three dimensions, as a result of these measurements. Such preliminary color values are then converted to the other values such as hue, saturation, lightness, and coordinates in two-dimensional color plates. Interestingly, two different but mutually correlated color systems (color coordinates) are used in colorimetry: XYZ colors and RGB colors. XYZ colors have been mainly used to calculate colors, whereas we recently succeeded to plot colors on color circle based on the measurement of RGB colors.

Human color vision differs from person to person, not only when color deficiencies occur but also within color-normal populations. Investigating individual variability in normal color vision is beneficial both for clinical purposes and for quantifying observer metamerism. Researchers have used color matches such as Rayleigh matches, Moreland matches, the D&H color rule, and various combinations of different media for such investigations. However, none of them were originally aimed at investigating the interobserver variability in color-normal populations, but rather were aimed at screening for color-deficiencies. The objective of this study was, therefore, to design and carry out a color matching experiment where observer variability appeared as large as possible to detect the interobserver differences in the color-normal population. Color matching was simulated under different combinations of reference spectrum and matching primaries using ColorChecker patches, different display/projector primaries, and the Stiles and Burch 49 observers. The simulation results showed: (1) The choice of spectra for the matching primaries had a significant effect on observer variability, (2) observer variability was large for near-neutral reference colors, and (3) observer variability in the lightness direction was small relative to chromatic variability. The color matching experiment highlighting interobserver variability was designed based on these three findings and carried out for 61 color-normal observers. Typical interobserver variability was 9.2 mean color difference from the mean (MCDM) using CIEDE2000 (spanning about 40 CIELAB units), which was much larger than any previous experiment. The obtained color matching data are useful for derivation, validation, and analysis of color matching functions. © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015

In a color matching experiment, the colors of two stimuli might match perfectly to one observer. However, to another, those same two stimuli might not match depending on the spectral characteristics of the two stimuli and each of the observers' visual responses. This phenomenon, that any two observers perceive color matches differently, is termed observer metamerism. Only recently have differences in the factors that affect the spectral response of the human eye been quantified to a degree such that observer metamerism can be realistically modeled over a representative population of human observers. From the statistics of these factors, a large, representative group of such observers—each said to be metameric to a standard—was created in terms of LMS cone spectral responses. Using analysis of variance and error propagation, as suggested by Nimeroff, this sample set was reduced to a complete colorimetric description that includes mean color matching functions along with variance and covariance functions. This simplified representation is then applied to creating arbitrary sets of color matching functions, such as the CIE 1931 and 1964 observers, and their covariance functions to allow the practical characterization of observer-metameric mismatch gamuts for any nominally metameric stimulus pair. © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015

The introduction of a wide-gamut color space in ultrahigh-definition (UHD) television creates a need to match colors on wide-gamut UHD displays with colors on conventional high-definition (HD) displays. Many contemporary color conversion methods that apply to conversion from HD to standard definition (SD), and color conversion methods mandated by current television standards, fail to produce a good color match when converting colors from HD or narrow-gamut UHD color spaces to the wide-gamut UHD color space. This paper illustrates the color errors caused by the application of several of these conversion methods and recommends one method, using display-referred colorimetry, for better color matching between narrow-gamut and wide-gamut displays.

In this paper a non-parametric model based on Wasserstein CNN is proposed for color correction. It is suitable for large-scale remote sensing image preprocessing from multiple sources under various viewing conditions, including illumination variances, atmosphere disturbances, and sensor and aspect angles. Color correction aims to alter the color palette of an input image to a standard reference which does not suffer from the mentioned disturbances. Most of current methods highly depend on the similarity between the inputs and the references, with respect to both the contents and the conditions, such as illumination and atmosphere condition. Segmentation is usually necessary to alleviate the color leakage effect on the edges. Different from the previous studies, the proposed method matches the color distribution of the input dataset with the references in a probabilistic optimal transportation framework. Multi-scale features are extracted from the intermediate layers of the lightweight CNN model and are utilized to infer the undisturbed distribution. The Wasserstein distance is utilized to calculate the cost function to measure the discrepancy between two color distributions. The advantage of the method is that no registration or segmentation processes are needed, benefiting from the local texture processing potential of the CNN models. Experimental results demonstrate that the proposed method is effective when the input and reference images are of different sources, resolutions, and under different illumination and atmosphere conditions.

Aim The purpose of this study was to compare conventional shade matching method with digitally assisted shade matching method and to evaluate observer's shade matching ability using conventional method in day light as well as studio environment and to compare it with digital. Materials and methods The ten observers with normal vision and color acuity participated in the study. Twenty subjects selected, satisfying exclusion and inclusion criteria of the study. Target tooth selected for study was vital right maxillary central incisor. A Vita classical shade guide was used for shade matching. Computer system, digital camera and Digital color matching software and were used for digitally assisted shade matching method. For conventional shade matching, observers performed shade selection in day light as well as in studio environment, at the same time digital images of the target tooth were made, and processed through the digital color matching software for digitally assisted. Results The chi-square analysis showed that the observer's matching ability is not significantly different in either day light ( P = 0.164) or in studio environment ( P = 0.300). Overall correct matching ability of ten observers was 58.5% and 52.5% in day light and in studio environment respectively. Conclusions Within the limitations of current study a new computer matching method was proposed and found to be superior to the conventional shade matching method. Large variation in observer's ability in conventional shade matching was also found.