Color Pairs Research Articles

The Color Harmony Estimation Model Construction Based on Two Layers of MLE and BPNN in the Color Matching Field

In the field of art, color matching is widely used in various art designs, such as images, posters, clothing, and interior home design. Among them, harmonious color matching is the decisive factor in whether a design is popular or not. To solve the problem of estimating color harmony, this study analyzes from the perspective of color pairs and uses the two-layer maximum likelihood estimation method to make preliminary predictions of color harmony by statistically modeling paired color preferences in existing datasets. After obtaining the preliminary estimation of color harmony, multiple linear regression is selected for denoising processing. Subsequently, the preliminary prediction results were refined using a backpropagation neural network, extracting various color features in different color spaces, and ultimately obtaining accurate harmony estimates. The results indicate that, compared with existing methods, the proposed method can simulate the aesthetic cognition of different users towards different color themes. Under the same statistical method, the model can maintain good harmony estimation and experimental results. This method can promote the development of related research fields, such as quickly evaluating the color harmony of an image, and one click color changing in scenes such as clothing, home, 3D models, etc. according to different user needs.

"Warm," "cool," and the colors.

Participants judged affective cooler/warmer gradients around a 12-step color circle. Each pair of adjacent colors was presented twice (left-right reversed), all in random order. Participants readily performed the task, but their settings do not correlate very well. Individual responses were compared with a small number of canonical templates. For a little less than one-half of the participants responses or judgements correlate with such a template. We find a warm pole (in the orange environment) and a cool pole (in the teal environment) connected with two tracks that tend to have one or more gaps or weak, even inverted links. We conclude that the common artistic cool-warm polarity is only weakly reflected in responses of our observers. If it does, the observers apparently use categorical warm and cool poles and may be uncertain in relating adjacent hue steps along the 12-step color circle.

Visual stimulus structure, visual system neural activity, and visual behavior in young human infants.

In visual perception and information processing, a cascade of associations is hypothesized to flow from the structure of the visual stimulus to neural activity along the retinogeniculostriate visual system to behavior and action. Do visual perception and information processing adhere to this cascade near the beginning of life? To date, this three-stage hypothetical cascade has not been comprehensively tested in infants. In two related experiments, we attempted to expose this cascade in 6-month-old infants. Specifically, we presented infants with two levels of visual stimulus intensity, we measured electrical activity at the infant cortex, and we assessed infants' preferential looking behavior. Chromatic saturation provided a convenient stimulus dimension to test the cascade because greater saturation is known to excite increased activity in the primate visual system and is generally hypothesized to stimulate visual preference. Experiment 1 revealed that infants prefer (look longer) at the more saturated of two colors otherwise matched in hue and brightness. Experiment 2 showed increased aggregate neural cortical excitation in infants (and adults) to the more saturated of the same pair of colors. Thus, experiments 1 and 2 taken together confirm a cascade: Visual stimulation of relatively greater intensity evokes relatively greater levels of bioelectrical cortical activity which in turn is associated with relatively greater visual attention. As this cascade obtains near the beginning of life, it helps to account for early visual preferences and visual information processing.

Profuse color-evolution based aptasensor for mucin 1 detection utilizing urease-mediated color mixing of the mixed pH indicator

Mucin 1 is a significant tumor marker, and developing portable and cost-effective methods for its detection is crucial, especially in resource-limited areas. Herein, we developed an innovative approach for mucin 1 detection using a visible multicolor aptasensor. Urease-encapsulated DNA microspheres were used to mediate multicolor change facilitated by the color mixing of the mixed pH indicator, a mixed methyl red and bromocresol green solution. Distinct color changes were exhibited in response to varying mucin 1 concentrations. Notably, the color mixing of the mixed pH indicator was used to display various hues of colors, broadening the range of color variation. And color tonality is much easier to differentiate than color intensity, improving the resolution with naked-eyes. Besides, the variation of color from red to green (a pair of complementary colors) enhanced the color contrast, heightening sensitivity for visual detection. Importantly, the proposed method was successfully applied to detect mucin 1 in real samples, demonstrating a clear differentiation of colors between the samples of healthy individuals and breast cancer patients. The use of a mixed pH indicator as a multichromatic substrate offers the merits of low cost, fast response to pH variation, and plentiful color-evolution. And the incorporation of calcium carbonate microspheres to encapsulate urease ensures stable urease activity and avoids the need for extra urease decoration. The color-mixing dependent strategy opens a new way for multicolor detection of MUC1, characterized by vivid color changes.

Tensorial Evolutionary Optimization for Natural Image Matting

Natural image matting has garnered increasing attention in various computer vision applications. The matting problem aims to find the optimal foreground/background (F/B) color pair for each unknown pixel and thus obtain an alpha matte indicating the opacity of the foreground object. This problem is typically modeled as a large-scale pixel pair combinatorial optimization (PPCO) problem. Heuristic optimization is widely employed to tackle the PPCO problem owing to its gradient-free property and promising search ability. However, traditional heuristic methods often encode F/B solutions to a one-dimensional (1D) representation and then evolve the solutions in a 1D manner. This 1D representation destroys the intrinsic two-dimensional (2D) structure of images, where the significant spatial correlations among pixels are ignored. Moreover, the 1D representation also brings operation inefficiency. To address the above issues, this article develops a spatial-aware tensorial evolutionary image matting (TEIM) method. Specifically, the matting problem is modeled as a 2D Spatial-PPCO (S-PPCO) problem, and a global tensorial evolutionary optimizer is proposed to tackle the S-PPCO problem. The entire population is represented as a whole by a third-order tensor, in which individuals are classified into two types: F and B individuals for denoting the 2D F/B solutions, respectively. The evolution process, consisting of three tensorial evolutionary operators, is implemented based on pure tensor computation for efficiently seeking F/B solutions. The local spatial smoothness of images is also integrated into the evaluation process for obtaining a high-quality alpha matte. Experimental results compared with state-of-the-art methods validate the effectiveness of TEIM.

Positive dependence for colored percolation.

For uniform random 4-colorings of graph edges with colors {a,b,c,d}, every two colors form a 1/2- percolation, and every two overlapping pairs of colors form independent 1/2-percolations. We show positive mutual dependence for pairs of colors ab,ac, and ad, and negative mutual dependence for pairs of colors ab,ac, and bc. The proof is based on a generalization of the Harris-Kleitman inequalities. We apply the results to crossing probabilities for the colored bond and site percolation, and to colored critical percolation that we also define.

Brain stimulation with 40 Hz heterochromatic flicker extended beyond red, green, and blue

Alzheimer’s disease (AD) is associated with electrophysiological changes in the brain. Pre-clinical and early clinical trials have shown promising results for the possible therapy of AD with 40 Hz neurostimulation. The most notable findings used stroboscopic flicker, but this technique poses an inherent barrier for human applications due to its visible flickering and resulting high level of perceived discomfort. Therefore, alternative options should be investigated for entraining 40 Hz brain activity with light sources that appear less flickering. Previously, chromatic flicker based on red, green, and blue (RGB) have been studied in the context of brain-computer interfaces, but this is an incomplete representation of the colours in the visual spectrum. This study introduces a new kind of heterochromatic flicker based on spectral combinations of blue, cyan, green, lime, amber, and red (BCGLAR). These combinations are investigated by the steady-state visually evoked potential (SSVEP) response from the flicker with an aim of optimising the choice of 40 Hz light stimulation with spectrally similar colour combinations in BCGLAR space. Thirty healthy young volunteers were stimulated with heterochromatic flicker in an electroencephalography experiment with randomised complete block design. Responses were quantified as the 40 Hz signal-to-noise ratio and analysed using mixed linear models. The size of the SSVEP response to heterochromatic flicker is dependent on colour combinations and influenced by both visual and non-visual effects. The amber-red flicker combination evoked the highest SSVEP, and combinations that included blue and/or red consistently evoked higher SSVEP than combinations only with mid-spectrum colours. Including a colour from either extreme of the visual spectrum (blue and/or red) in at least one of the dyadic phases appears to be more important than choosing pairs of colours that are far from each other on the visual spectrum. Spectrally adjacent colour pairs appear less flickering to the perceiver, and thus the results motivate investigations into the limits for how alike the two phases can be and still evoke a 40 Hz response. Specifically, combining a colour on either extreme of the visual spectrum with another proximal colour might provide the best trade-off between flickering sensation and SSVEP magnitude.

Image recoloring for color vision deficiency compensation using Swin transformer

People with color vision deficiency (CVD) have difficulty in distinguishing differences between colors. To compensate for the loss of color contrast experienced by CVD individuals, a lot of image recoloring approaches have been proposed. However, the state-of-the-art methods suffer from the failures of simultaneously enhancing color contrast and preserving naturalness of colors [without reducing the Quality of Vision (QOV)], high computational cost, etc. In this paper, we propose an image recoloring method using deep neural network, whose loss function takes into consideration the naturalness and contrast, and the network is trained in an unsupervised manner. Moreover, Swin transformer layer, which has long-range dependency mechanism, is adopted in the proposed method. At the same time, a dataset, which contains confusing color pairs to CVD individuals, is newly collected in this study. To evaluate the performance of the proposed method, quantitative and subjective experiments have been conducted. The experimental results showed that the proposed method is competitive to the state-of-the-art methods in contrast enhancement and naturalness preservation and has a real-time advantage. The code and model will be made available at https://github.com/Ligeng-c/CVD_swin.

Harmonious colouring of line graph of commuting and non-commuting graph of D_{2n}

Harmonious coloring of graph \(G\) is a proper vertex coloring, where each pair of colors occurs at most on one pair of adjacent vertices. Minimum number of colors required for Harmonious coloring of \(G\) is the harmonious chromatic number, \(\chi_{H}(G)\). Here we determine the Harmonious chromatic number of the line graph of commuting graph and non-commuting graph of the dihedral group, \(D_{2n}\).

Adaptation under dichromatic illumination.

Over the years, many CATs (chromatic adaptation transforms) have been developed, such as CMCCAT97, CAT02 and CAT16, to predict the corresponding colors under different illuminants. These CATs were derived from uniform simple stimuli surrounded by a uniform background with a single illuminant. Although some mixed adaptation models have been proposed in literature to predict the adaptation under more than one illuminant, these models are typically limited to a certain scene and exclude the impact of spatial complexity. To investigate chromatic adaptation under more complex conditions, an achromatic matching experiment was conducted with (simultaneously) spatially dichromatic illumination for three illumination color pairs and various spatial configurations. Spatial configuration was found to have an impact on both the degree of adaptation and the equivalent illuminant chromaticity, which is the chromaticity of a single uniform adapting illumination that results in the same corresponding colors as for the dichromatic lighting condition. A preliminary CAT model is proposed that considers the spatial and colorimetric complexity of the illumination.

The impact of display saturation on visual search performance in congenital colour vision deficiency.

Colour-related search tasks are common in many professional fields. The study investigated whether increasing chromatic saturation can enhance the visual performance of individuals with colour vision deficiency (CVD) in colour-related search tasks. 10 normal trichromats (5M, 5F; Mean (SD) age: 23.1 (3.3) years) and 15 individuals with CVD [8 deutans and 7 protans identified by HRR plates] (14M, 1F; aged 28.6 (8.7) years) participated in this study. Four naturalistic sceneries of everyday tasks/ birds, animals and flowers of 15 different colour combinations (1 pair of colours in each combination. e.g., 'brown/black' or 'red/green') were presented in 'low' saturation, 'original' (unaltered images) and 'high' saturation condition using the Psychopy program on a colour-calibrated monitor. On each trial, the subject was asked to identify a specific-coloured target. Overall, the visual search performance index (expressed as product of accuracy and a reciprocal of reaction time (%correct*s-1) of the normal trichromats [Mean (SD):77.76% correct*s-1 (16.32)] was significantly higher than CVD [45.71% correct*s-1 (18.95)] in the "original" test images (p = 0.001), but in individuals with CVD, there was no significant difference between 'original' [45.71% correct*s-1 (18.95)] and 'high' saturation condition ([47.43% correct*s-1 (20.07)]; p > 0.05). However, colour-wise, increased saturation showed improvements (≥ 10%) in protans mainly for 'red' combinations with other colours such as white (i.e., 'red/white'), purple, orange, grey, green, brown and black. The study suggests that increasing the saturation of certain colour combinations can potentially aid in the visual search performance of individuals with CVD. This knowledge will help in better counselling and management of the patients.

An investigation of color difference for binocular rivalry and a preliminary rivalry metric, ΔE*bino

AbstractHead‐mounted displays (HMDs) for virtual and augmented reality applications could have severe nonuniformities due to complex optical components and the choice of light source technologies. In addition, module variations between the two eyes can result in different colors being seen with the left and right eyes. Binocular rivalry is expected for large color differences between the two eyes, which can severely affect product usability. Thus, it is important to characterize and predict the binocular rivalry in HMDs caused by interocular color differences. As a step toward this end, we propose the first binocular color difference metric, ΔE*bino, to predict the just noticeable binocular rivalry for a pair of solid colors. A psychophysical experiment was conducted using Meta Quest 2, in which we presented different colors to the left and right eye. The collected data were analyzed to derive the metric using ROC curves. We show that the ΔE*bino metric showed significant improvements over conventional color difference formulae. Both the ΔE*bino formula and the anonymized experiment results are available for download.

Poster Session: Learned rapid adaptation to environmental color changes generalize to a large range of colors.

When the environment changes color, vision adapts, and the world gradually appears less tinted. For repeated color changes, vision may learn to adapt faster to maintain accurate perception. We previously reported that wearing red glasses repeatedly caused the world to appear less and less reddish when the glasses were first put on, as measured by the appearance of unique yellow. Here, we tested the appearance of a larger range of colors. 13 observers wore red glasses for 5hr/day for 5 days. Observers were tested with pairs of 1.5 deg filled color circles, centered within a 6deg black square on a background image. 13 colors were chosen from LAB space comprising unique and intermediate hues at two contrast levels, and one gray. Observers rated the difference between each possible color pair on a scale of 0 to 9. Observers performed the task before and immediately after putting the glasses on, and after 25, 50 and 75 min of wear. Wearing red glasses caused all colors to appear reddish and be rated as relatively similar. As observers adapted, colors gradually regained more normal appearance, and the similarity between color pairs decreased. Critically, over days, color pairs appeared more dissimilar immediately after putting on the glasses (p<1e-6). Multi-dimensional scaling analysis of the similarity data revealed a uniform expansion of color space across days. Thus, observers learned to immediately adjust their perception of many colors with repeated experience.

The effect of lightness, chroma, and hue on depth perception

AbstractColor coding of the graphical user interface (GUI) is effective in cognitive tasks, especially searching and identifying target stimuli from a crowded GUI. The perceived color depth on a flat GUI is a critical feature in mapping the stratification of information. In color science, the visual phenomena of advancing and receding colors provide the perceived depth needed for GUI design. The experiment used a series of color pairs as experimental samples to observe the phenomenon of depth perception caused by colors and obtain the judgment of the perception of color depth. This study developed a best‐fit regression model to predict the perceived color depth. The study found that the higher the lightness, the higher the chroma, and the closer the hue is to 33° (reddish color), the colors tend to be the advancing colors; the lower the lightness, the lower the chroma, and the closer the hue is to 213° (blue‐greenish color), the colors tend to be the receding colors.

Single‐conflict colorings of degenerate graphs

AbstractWe consider the single‐conflict coloring problem, a graph coloring problem in which each edge of a graph receives a forbidden ordered color pair. The task is to find a vertex coloring such that no two adjacent vertices receive a pair of colors forbidden at an edge joining them. We show that for any assignment of forbidden color pairs to the edges of a ‐degenerate graph on vertices of edge‐multiplicity at most , colors are always enough to color the vertices of in a way that avoids every forbidden color pair. This answers a question of Dvořák, Esperet, Kang, and Ozeki for simple graphs.

Fifteen ceramic gingival samples: A proposed gingival shade guide

Objective(1) To put forward a set of valid pink ceramic samples for subjective gingival colour selection in the Caucasian population, and (2) to assess the quality of the shade matches provided by the selected pink samples. MethodsThe ceramic gingival shade samples (n = 133) were obtained by mixing pairs of basic colours from a single system. In each mixture, the proportions of the colours were altered in 10% increments, following the numerical order used by the manufacturers of the three colour systems under study (Heraceram, Vita VM9 and IPS Style). The CIELAB colour coordinates were recorded using spectrophotometry in three zones of healthy anterior gingiva (n = 360). The sample was randomly divided into two subsamples, each of which contained 180 participants. Subsample 1 was used to select the ceramic gingival samples that provided the best shade matches, using the k-means clustering method. Subsample 2 was used to assess the chromatic validity of the selected gingival samples, according to the coverage error. ResultsTo identify the ceramic gingival samples that best represented participants’ gingival colour, the minimum colour differences (ΔEab∗, ΔE00) between the cluster centroids and the 133 gingival samples were calculated. Fifteen gingival samples were selected: 8 from the Heraceram system, 4 from the VM9 system, and 3 from the IPS Style system. Coverage errors for the 15 gingival samples fell below the gingival clinical acceptability thresholds in the three gingival zones examined. ConclusionsThe 15 ceramic gingival colour samples provide satisfactory coverage of the gingival colour space, with coverage errors below the ΔE00 clinical acceptability threshold of 2.9 units. These pink colour samples have the potential to provide good gingival shade matches in subjective colour selection. Clinical SignificanceMixing basic ceramic colours is a viable method for generating a series of pink shades that can be used as a physical gingival shade guide. The resulting guide provides valid results (under the acceptability thresholds) for subjective selection gingival colour selection in clinical practice.

BILANGAN KROMATIK HARMONIS PADA GRAF PAYUNG, GRAF PARASUT, DAN GRAF SEMI PARASUT

This article discusses the harmonic coloring of simple graphs G, namely umbrella graphs, parachute graphs, and semi-parachute graphs. A vertex coloring on a graph G is a harmonic coloring if each pair of colors (based on edges or pair of vertices) appears at most once. The chromatic number associated with the harmonic coloring of graph G is called the harmonic chromatic number denoted XH(G). In this article, the exact values ​​of harmonic chromatic numbers are obtained for umbrella graphs, parachute graphs, and semi-parachute graphs.

Color induction in the restoration of architecture in historic city centers

AbstractIn the restoration of historic facades, specialists need to tackle the problem of colors applied to the ornamental elements that appear different on a facade than if they were isolated, because the colors of the surrounding surfaces influence them through color induction. This study evaluates the difference between the colors of ornaments observed in isolation, which we call nominal colors, and on different background colors, which we call induced colors, considering the historic color palette of Valencia as studied by the Color Research Group in Architecture of the Universitat Politècnica de València. The study consisted of the evaluation of 108 color pairs painted on physical cardboards, rated by 26 female students (average age 26.5), under natural lighting conditions, and using the Natural Color System (NCS) Color Atlas for the color match. Results indicate that induced colors have lower NCS blackness compared with nominal ones, and slightly higher or no NCS chromaticness shift. Nominal colors with low chromaticness exhibit an important hue induction effect and tend to shift to a hue that is located opposite to that of the background color in the NCS color circle, this effect being larger when the background has a warm color. The induction effect is larger when ornamental elements and background have similar nominal NCS blackness, and different nominal NCS chromaticness,with nominal hue difference no significant in the induction effect. The colors of ornamental elements that entailed greater induction were those with the lowest NCS chromaticness, and in the case of the background color, those with the highest chromaticness.

Androgens and child behavior: Color and toy preferences in children with congenital adrenal hyperplasia (CAH)

Human males and females show average gender/sex differences for certain psychological phenomena. Multiple factors may contribute to these differences, including sex chromosomes, exposure to gonadal hormones, and socialization or learning. This study investigated potential hormonal and socialization/learning influences on gender/sex differences in childhood preferences for color, specifically pink and red vs. blues, and for toys. Children (aged 4 to 11 years) with congenital adrenal hyperplasia (CAH, n = 43 girls and 37 boys), marked by elevated prenatal adrenal androgen exposure, and without CAH (n = 41 girls and 31 boys) were studied. Prior research indicates girls with CAH are masculinized for certain behaviors, such as toy choices, while boys with CAH generally do not differ from boys without CAH. In the current study, children indicated preferences for stereotyped hues of pink vs. blue as well as two control color pairs. They also indicated their preference between gender/sex-typed toys (doll vs. car) presented in black and white, in gender/sex-congruent colors (pink doll vs. blue car) and in gender/sex-incongruent colors (pink car vs. blue doll). Color findings: Control girls preferred stereotyped pink over blue more than boys or girls with CAH did; the latter two groups did not differ in their color preferences. No preference differences occurred for other color pairs. Toy findings: In black/white or gender/sex-congruent colors, boys preferred the car more than control girls or girls with CAH did, while girls with CAH preferred the car more than control girls did. In gender/sex-incongruent colors (pink car vs. blue doll), boys still preferred the car, while girls with CAH showed reduced and control girls showed increased preferences for the pink car compared to the car preferences in black/white. Results support learning theories of color preferences, perhaps also influenced by pre-existing toy preferences which may occur for other reasons, including early androgen exposure. Specifically, girls with CAH may have learned they do not enjoy stereotypical toys for girls, often colored pink, and pink coloring may subsequently diminish their preference for a car. Our results highlight the importance of gonadal hormones and learning in the development of childhood toy and color preferences.

EGA-Net: Edge feature enhancement and global information attention network for RGB-D salient object detection

With the supplement of texture and geometry cues in depth maps, salient object detection (SOD) shifts from 2D to 3D, aiming to detect the most attractive object in a pair of color and depth images. Previous work primarily focused on regional integrity. Few methods are used to improve the edge quality of prediction results, resulting in a final prediction with a complete structure but blurred edges. Moreover, due to the complexity of real-life scenarios, the problem of effectively separating the salient object from complex background has become a hot potato. Aiming to address these issues, we propose a novel network, EGA-Net, to improve the edge quality and highlight the main features of the salient object. Specifically, in the EGA-Net, we propose a feature interaction (FI) module and an edge feature enhancement (EFE) module, respectively. Among them, the FI module is used to remove unimodal feature redundancy, capture multi-modal feature complementarity, and reduce the contamination of low-quality depth maps. The EFE is used to improve the edge quality of the final salient object prediction results. Furthermore, a Global Information Guide Integration (GIGI) module has been proposed to suppress the background noise and effectively highlight the salient objects’ main features. It uses interleaving and fusion methods to automatically select and enhance the vital information in the original input features under the guidance of global features. We put the training of EGA-Net under the supervision of a new hybrid loss function that can simultaneously take global pixel point, foreground, and depth map quality into account. Quantitative and qualitative experiment results demonstrate that our method outperforms the 19 advanced methods on eight publicly available RGB-D salient object detection datasets with five evaluation metrics. You can find the code and results of our method athttps://github.com/guanyuzong/EGA-Net.