Color Matching Research Articles

Individual color matches and cone spectral sensitivities in 100 observers of varying age

Individual color matches and cone spectral sensitivities in 100 observers of varying age

COMPARATIVE ASSESSMENT OF VISUAL COLOR MATCHING FOR ARTIFICIAL AND NATURAL TEETH BY STUDENT OF DENTAL FACULTY AT KHARKIV NATIONAL MEDICAL UNIVERSITY

The purpose of this study was to conduct a comparative assessment of dental students’ ability to match the color of patients’ teeth with aesthetic restorations. Materials and Methods. The study was conducted from 2021 to 2024 with participation of 2nd- and 3rd-year students at the Faculty of Dentistry, Kharkiv National Medical University, Kharkiv, Ukraine. Results. Accurate determination and reproduction of natural tooth color is a challenging task in aesthetic dentistry, as color plays a crucial aesthetic role. This process depends heavily on the experience and perception of dentists and can be approached subjectively (visual analysis) or objectively (special devices). Although shade determination is a routine task for dentists, errors are still common. The study revealed that 2nd-year students struggled significantly with color matching, especially for natural teeth, with error rates of 66.6% for artificial teeth and 80.8% for natural teeth, indicating a need for more training. Students performed better using the VITA Classic shade guide, which is simplified, but matching the color of natural teeth requires additional practice. The results confirm that clinical training improves students’ color-matching skills. After training, 3rd-year students showed a marked decrease in error rates: 35.8% for artificial teeth and 53.3% for natural teeth. The Vita 3D Master scale proved more accurate due to its broader color-matching capabilities. Overall, the accuracy levels improved significantly, highlighting the effectiveness of the training program. Conclusion. The results of the study demonstrate that training significantly improves students' ability to accurately determine tooth color. The 3rd year students who underwent clinical training showed better results in matching the color of both artificial and natural teeth, reducing the number of errors by 35.8% and 53.3%, respectively. The Vita 3D Master scale proved to be more accurate due to a wider selection of colors and more evaluation parameters. The 81.5% increase in the overall score confirms the effectiveness of the training in improving the accuracy of tooth color determination in the educational process.

Deep Search for a Scattered Light Dust Halo Around Vega with the Hubble Space Telescope

We present a provisory scattered-light detection of the Vega debris disk using deep Hubble Space Telescope (HST) coronagraphy (PID 16666). At only 7.7 pc, Vega is immensely important in debris disk studies both for its prominence and also because it allows the highest physical resolution among all debris systems relative to temperature zones around the star. We employ the STIS coronagraph’s widest wedge position and classical reference differential imaging to achieve among the lowest surface-brightness sensitivities to date ( ∼4μJyarcsec−2 ) at wide separations using 32 orbits in Cycle 29. We detect a halo extending from the inner edge of our effective inner working angle at 10.″5 out to the photon noise floor at 30″ (80–230 au). The face-on orientation of the system and the lack of a perfectly color-matched point-spread function star have posed significant challenges to the reductions, particularly regarding artifacts from the imperfect color matching. However, we find that a halo of small dust grains provides the best explanation for the observed signal. Unlike Fomalhaut (a close twin to Vega in luminosity, distance, and age), there is no clear distinction in scattered light between the parent planetesimal belt observed with the Atacama Large Millimeter/submillimeter Array and the extended dust halo. These HST observations complement JWST GTO Cycle 1 observations of the system with NIRCam and MIRI.

Specification of just‐noticeable color difference for 2° and 10° stimuli using different color matching functions

AbstractJust‐noticeable color difference (JNCD) is important in color specification and characterization. The commonly referenced specification of JNCD (i.e., 0.004 or 0.0033 u′v′ unit) is thought to originate from the MacAdam ellipses, which were derived using 2° color stimuli and characterized using the CIE 1931 2° color matching functions (CMFs). However, there is no universally agreed or clear definition of JNCD. Also, such a specification is widely used in various ways based on an assumption that it is applicable regardless of the actual size of the stimuli and CMFs. In this study, an experiment using a constant stimuli method was carried out. The human observers evaluated a series pairs of test and reference stimuli, with a field of view (FOV) of 2° or 10°. The chromaticities of the test stimuli were carefully calibrated using four standard CIE CMFs (i.e., CIE 1931 2°, 1964 10°, 2006 2°, and 10° CMFs). The results suggested that the widely used specification of JNCD seems to be derived based on the one standard deviation ellipses, the use of these four CMFs has little effect on the specification, and the JNCD value for stimuli with an FOV of 10° is 0.0025–0.0027 u′v′ unit depending on the CMFs.

3D-Printed Permanent Resin Crowns on Pre-Molar and Molar Teeth; Two-Year Results of a Prospective Clinical Study.

The aim of this prospective clinical study was to evaluate the 12 and 24-month clinical results of overlay and one-piece endodontic crown restorations applied with additively manufactured 3D printed permanent ceramic-filled resin (PCR) according to the Modified US Public Health Service (USPHS) criteria. A total of 33 indirect restorations (16 overlay, 17 endocrown) (4 premolar, 29 molar) produced using PCR (Formlabs) were applied to 30 patients by a single dentist. The restorations were evaluated according to the modified USPHS criteria at baseline (7 days), 12 and 24 months times by two independent evaluators. The study registration number is NCT05168852. In the comparisons of the dependent criteria scores, the Related Samples Cochran Q test was used, and in post-hoc paired comparisons, the Bonferroni test. The Fisher-Freeman-Halton test was applied in the comparisons of categorical variables according to the restoration type groups (α = 0.05). No statistically significant difference was determined between the evaluation criteria scores at baseline, 12 months, and 24 months for the marginal adaptation (P=0.05), retention (P=1), interproximal contact (P=0.368), color match (P=1), surface texture (P=1), and patient satisfaction (P=1). The only score criteria that showed a statistically significant difference between baseline and 24 months (P=0.001) among all other criteria was marginal discoloration. This criteria's score change was from 100% A score to 69.7% A score. In the 2-year follow-up of indirect single-tooth restorations produced with 3D-printed PCR, all restorations showed acceptable clinical performance. (≥99.5%A+B score at 2 years).

Conventional suspension delivery versus tattooing pen-assistedsuspension delivery in non-cultured epidermal cell suspension procedure for vitiligo: A randomized controlled trial.

Non-cultured epidermal suspension (NCES) is one of the most widely used surgical therapy for stable vitiligo patients in which recipient size preparation plays an important role in the outcome of NCES. The primary objective is to evaluate and compare the efficacy and safety of conventional suspension delivery after manual dermabrasion (CSMD) versus tattooing pen-assisted suspension delivery (TPSD) in NCES. Paired vitiligo units (VU) in 36 patients, matched with respect to size and location were divided into two groups. The VU in Group 1 underwent suspension delivery by CSMD while the VU in Group 2 underwent same by TPSD. All the VU were followed up at regular intervals until 24 weeks. At the end of 24 weeks, 31 VU (86.1%) in Group 1 achieved >75% repigmentation which was significantly higher (p = .02, chi-square test) as compared to 22 VU (61.1%) in Group 2. The color matching in both the groups VU was also comparable (p = .84, chi-square test). The patient global assessment (PGA) was significantly higher in Group 1 VU as compared to Group 2. Treatment response in terms of repigmentation and PGA was significantly better in VU treated with CSMD as compared to TPSD. Recipient site complications were seen more commonly in Group 1 VU as compared to Group 2. Perilesional halo at the recipient site was seen in none of the VU in Group 2 which was significantly lower than 6 VU in Group 1 than (p = .02, chi-square test). Better results may be possible with technical improvisations in tattooing pen needle diameter and depth of penetration.

Emotional Colour Matching of Exhibition Hall Layout by Aesthetic Experience Theory

Emotional Colour Matching of Exhibition Hall Layout by Aesthetic Experience Theory

Optimization Analysis of Clothing Fabric Design Based on Autoencoder and Generative Adversarial Neural Network

In order to meet the challenges of increasingly diverse clothing styles and consumer demands in the market, traditional fabric design methods have become difficult to meet the needs of rapid iteration and innovation due to their time-consuming, costly, and subjective preferences of designers. In view of this, we propose an innovative fabric design optimization simulation strategy aimed at breaking through these bottlenecks through technological means. This strategy cleverly integrates advanced technologies of variational autoencoder (VAE) and generative adversarial network (GAN). First, VAE is used to capture and learn the complex distribution characteristics of existing clothing fabric designs, which include key information such as fabric texture, color matching, and structural details. Subsequently, GAN uses the hidden vectors obtained from VAE as input to generate brand new fabric design samples. During the training phase, GAN continuously iterates and optimizes, engaging in intense “adversarial” interactions between its generator and discriminator. The generator is dedicated to creating new samples that are as close to real fabric designs as possible, while the discriminator is responsible for identifying the authenticity of these samples. This process is implemented through backpropagation (BP) loss function, ensuring that the generated fabric design can visually simulate real fabrics. Experimental verification shows that this method can not only effectively generate high-quality and realistic clothing fabric designs, but also greatly shorten the design cycle and reduce costs.

Effect of Hyaluronic Acid Mucoadhesives on Palatal Wound Healing and Postoperative Discomfort in Free Gingival Graft Surgery: A Clinical Trial

Objectives: This study aimed to assess the effect of hyaluronic acid (HA) mucoadhesives with two different concentrations on palatal epithelial wound healing and postoperative discomfort following free gingival graft (FGG) surgery. Materials and Methods: In this triple-blind, randomized, controlled clinical trial, 39 patients undergoing FGG surgery were randomly allocated to three groups (N=13). Following palatal graft harvesting, the two experimental groups received mucoadhesives containing 0.8% and 0.2% HA, while the control group received mucoadhesives without HA. In all groups, the donor site was protected with periodontal dressing. Epithelization, color match, contour, and distortion were assessed at 3, 7, 14, 21, and 42 days, postoperatively using the Landry's healing index and modified Manchester Scar Proforma (mMSP) index. Pain level and response to thermal stimuli were evaluated after 3, 7, 14, and 21 days using a visual analog scale (VAS). Data were analyzed by the Chi-square, Kruskal-Wallis, Mann-Whitney, Friedman, and Wilcoxon signed-rank tests (alpha=0.05). Results: Significant differences were observed in the mMSP index scores among the groups at 3, 7, 14, and 42 days, favoring HA groups (P<0.05). The Landry's healing index score was significantly higher in 0.8% HA group on day 21 (P=0.023), compared to the control group. No significant differences were found in pain score or thermal stimulus responses among the groups (P>0.05). Conclusion: Mucoadhesives containing HA were found to enhance palatal wound healing, leading to improved outcomes in terms of epithelization, color match, contour, and distortion reduction.

Lateral Calcaneal Artery Perforator/Propeller Flap in the Reconstruction of Posterior Heel Soft Tissue Defects

Abstract Introduction Posterior heel soft tissue defects with/without tendoachilles injury are difficult to reconstruct because of bony prominence, limited expendable local soft tissues, and significant donor site morbidity. In this study, we evaluate the lateral calcaneal artery (LCA) perforator/propeller flap for posterior heel soft tissue defect reconstruction. Materials and Methods A preliminary cadaveric study was done on 22 specimens to study the course of the LCA and its perforators. The knowledge gleaned from the cadaveric study was applied in our clinical study. The clinical study was conducted from January 2018 to May 2023 in 13 patients (10 males and 3 females) with posterior heel defects. The primary movement of the perforator flaps were either V-Y advancement (n = 10) or propeller (n = 3). Results All the flaps settled well except for superficial epidermolysis in one patient (7.69%) which healed conservatively. The average follow-up period was 14.53 months. Postoperatively, all patients had normal gait and normal range of movements. The LCA with the maximum number of perforators in the retrofibular/retromalleolar segment and the islanded flaps based on these perforators provided the excellent coverage for tendoachilles insertion defects and posterior heel defects facilitating excellent shoeability in all cases. Conclusion The study concludes that the LCA perforator/propeller flap may be a reliable cover for the posterior heel defects with good color, texture, thickness, and contour match rendering a shoeable stable foot.

Individual color matching functions from cross‐media color‐matching experiment

AbstractHuman color vision exhibits substantial variability, challenging the accurate measurement and reproduction of individual color appearances. This paper introduces a novel cross‐media color‐matching experiment that combines physical pigments and digital displays, providing a practical and efficient solution to measure individual color matching functions (CMFs). By using the Kubelka–Munk theory to synthesize broadband spectral pigments, optimized metameric pairs can be created to significantly differentiate categorical observers. Psychophysical experiment results reveal the superiority of specific CMFs for individual observers, surpassing standard models like the CIE 1931 2‐degree CMFs. This study also underscores the significance of employing CMFs for personalized color reproduction and explores the potential benefits of using higher bit‐depth displays, narrower‐band displays, and increasing repetition counts to enhance the accuracy of the color matching process.

Potential execution of vitiligo surgery by the most conceivable technique – which, where, and why?

While various treatment options exist for vitiligo, surgical interventions have gained significant attention due to their potential for long-lasting repigmentation. Several surgical procedures have been developed, including miniature punch grafting, thin Theirsch’s split-thickness skin grafting (STSG), suction blister technique, and ultrathin STSG. The decision-making process should also consider the potential risks and benefits associated with each technique. Factors such as graft survival, color match, post-operative complications, and long-term stability of repigmentation should be evaluated. In addition, patient factors such as comorbidities, skin type, and psychological impact should be carefully considered to ensure optimal surgical outcomes. We, hereby, aim to explore the potential execution of vitiligo surgery using the most conceivable technique, considering factors such as efficacy, safety, and patient-specific characteristics.

Chromatic Adaption of Two Universal Composites: Spectrophotometric Analysis

Objective: The purpose of this study was to evaluate the chromatic adaptability and color stability of two different composite resins, Omnichroma and Estelite Bulk-Fill Flow, in Class V restorations at different times. Materials and methods: Standardized Class V cavities were prepared on the labial surface of 34 extracted intact and noncarious human permanent molars. The dental elements were randomly divided into two groups according to the resin composite material. Group 1 was restored with Omnichroma (Tokuyama Dental Corporation Inc., Tokyo, Japan) and Group 2 was restored with Estelite BulkFill Flow Universal (Tokuyama Dental Corporation Inc., Tokyo, Japan). Color properties were assessed using a spectrophotometer, SpectroShadeTM Micro (MHT Optic Research, Niederhasli, Switzerland), at baseline (T0), immediately after Class V restoration (T1), 24 h after restoration (T2) and after thermocycling (T3) (ISO/TS 11405, 2015 protocol). Color difference (ΔE) was analyzed with a Student’s t-test and a Wilcoxon–Mann–Whitney test to evaluate the differences, in terms of chromatic adaptability, between the two materials (inter-group analysis) while Kruskal–Wallis test e Two-way ANOVA statistical tests were used to evaluate the color stability of each material over time (intra-group analysis). Results: Regarding the inter-group analysis, there were no statistically significant differences between the two materials in all the comparisons: T0–T1 (p = 0.9025), T0–T2 (p = 0.2779), T0–T3 (p = 0.4694). Moreover, both groups showed an average ΔE > 2. In the intra-group analysis, no statistically significant differences were observed in either Group 1 (p = 0.954) or Group 2 (p = 0.8654). Conclusions: The in vitro color matching, assessed by spectrophotometry, of the two tested resin composites does not vary at different time intervals. Furthermore, even though both composites use different mechanisms to produce the color the human eye perceives, they show very similar chromatic adaptability.

Is It Possible for Single-shade Composites to Mimic the Color, Lightness, Chroma, and Hue of Other Single-shade Composites? An In Vitro Study.

This study aimed to assess color matching post-repair using the same or different single-shade composites of three distinct composite resin materials (Omnichroma-OM, ZenChroma-ZC, and Charisma Topaz One-CTO) following aging in coffee solution and distilled water. Evaluation focused on color change parameters (ΔE00, ΔL00, ΔC00, and ΔH00). Specimens were prepared in disk shape with a diameter of 8 mm and a height of 2 mm (n=180). Half of each composite group was immersed in distilled water, while the other half was immersed in coffee solution for 12 days each (n=90). After aging, cylindrical cavities with a diameter of 4 mm and a depth of 1 mm were prepared at the center of the specimens. The cavities were repaired with both themselves and other composite resins (n=10). Color measurements of the specimens were performed using VITA Easyshade 5 (VITA Zahnfabrik, Bad Säckingen, Germany) at the following time points: baseline (T0), after aging (12 days) (T1), immediately after repair (T2), one day after repair (T3), one week after repair (T4), and one month after repair (T5). Statistically significant differences were found in the mean ΔE00 measurements among the study groups at all time points for each of the three composite resins (p<0.05). Similarly, statistically significant differences were found in the mean ΔE00 measurements over time for each of the three composite resins in each study group (p<0.05). The baseline measurements of materials repaired with themselves in the distilled water groups and the final measurements of materials repaired with themselves in the coffee groups were found to be within acceptable ΔE00limits. At the end of the study, only CTO repaired with OM showed acceptable color matching with different composites in both coffee and distilled water groups. Acceptable color matching was achieved when using the same material for repair in specimens aged in distilled water and coffee. However, variations in matching were observed when different materials were used for repair, indicating the need for ongoing monitoring. Contributions of ΔL00, ΔC00, and ΔH00 values to color differences vary depending on the resins and repair process and change over time.

Pre-expanded Local Flaps: Optimal Choice for Repairing Defects Following Extensive Benign Tumor Resection in the Head and Face.

Treating extensive benign tumors of the head and face presents a longstanding challenge, necessitating efficacy at the lesion site, and postoperative esthetic considerations for the donor area. This study aims to explore the clinical outcomes of pre-expanded local flap reconstruction for extensive benign tumors of the head and face post resection. From March 2018 to March 2023, a total of 18 patients with extensive benign tumors of the head and face were admitted, including 13 cases of nevus, 2 cases of hemangioma, 2 cases of neurofibroma, and 1 case of verruca. Based on the location and size of the lesions, suitable local areas were selected for tissue expansion, and expanders were implanted for regular saline injections over 8 to 16 weeks. After reaching the desired expansion, resection of the head and facial tumors and local flap reconstruction were performed. Postoperatively, data on patients' information, tumor types, tumor area, expansion volume, postexpander complications, vascular condition after flap transfer, and donor site condition were collected. In this series of 18 patients, benign tumors of the head and face were completely repaired through 1 to 2 stages of tissue expansion surgeries. Postimplantation complications included hematoma in 1 case and infections in 2 cases, with one instance of expander infection leading to surgical failure. However, all other patients achieved adequate expansion, successful flap survival post-transfer, and experienced no other complications. Follow-up over 6 to 24 months showed no recurrence at the lesion sites, with flaps maintaining consistent color, texture, and thickness matching surrounding skin tissue. In addition, donor site healing was excellent, with no obvious surgical scars. Pre-expanded local flap reconstruction is an ideal method for repairing extensive benign tumors of the head and face postresection.

Automated painting color matching technology based on semantic intelligence understanding

Painting color matching technology is widely used in the production and printing process of products. Traditional painting and color matching have been unable to meet market demands. Based on this, a large-scale corpus under the existing semantic intelligent understanding system is used as the knowledge source. The computer automated painting color matching model is constructed. It is applied in case studies to address issues such as unclear query intentions, mismatched system retrieval terms, and return errors caused by uncertain factors such as synonyms and polysemy. This provides new ideas for the application of semantic intelligence understanding and automated painting color matching technology. The experimental results showed that the precision, recall, and F1 of the method used in the research were 0.8639, 0.8026, and 0.8309, respectively, significantly superior to commonly used methods. This indicates that the proposed automated painting color matching technology based on semantic intelligent understanding has high performance, which can effectively meet the painting color matching requirements.

A comparative study of shade-matching performance using intraoral scanner, spectrophotometer, and visual assessment

This study aimed to explore the clinical applicability of the shade-matching function in intraoral scanners. This study measured the tooth colors of maxillary anterior dentitions of 83 adults using visual matching, a spectrophotometer, and a scanner according to two color systems: VITA Classical (VC) and VITA 3D-Master (V3D). Agreement between each method was assessed by weighted Cohen’s kappa coefficient (KW, α = 0.05). For V3D, the overall agreement between the scanner and spectrophotometer (KW = 0.498) was higher than that between the scanner and visual matching (KW = 0.473). Similarly, the agreement between the scanner and spectrophotometer (KW = 0.283) was higher than that between a scanner and visual matching (KW = 0.140) for VC. Regarding tooth position, the highest agreement between the scanner and spectrophotometer was observed on the right central incisor (KW = 0.542) for V3D. Tooth color measurement with a scanner was comparable to that with a spectrophotometer, especially on the central incisors when using the VITA 3D-Master system. A scanner could serve as an alternative to a spectrophotometer for shade selection. However, color matching should still be visually verified.

Preparation of vascularized forearm dermal fat flap and repairing of donor site

Objective:This study prepared vascularized dermal fat flaps and introduced a local split-thickness skin graft from an in situ cutaneous area cutaneous area to manage forearm flap donor sites and evaluated the esthetic and functional outcomes post-operatively. From July 2020 to June 2023, 13 patients with soft tissue defects in Oral and Maxillary Area were repaired with tvascular forearm dermal fat flap. There were 8 males and 5 females, aged from 42-71 years. The flaps ranged from 8 cm×7 cm to 7 cm×5 cm in size. The donor site defects were covered by local split-thickness skin graft from the in situ skins. The color matching degree, surgical scars, ranges of wrist movement and hand sensations in donor forearms were assessed at 6 months after surgery. Results:The tvascular forearm dermal fat flaps for 15 cases all survived. All the local split-thickness skin grafts transplanted with this technique showed primary healing. The follow-up period for 6 months, Donor site exhibited suitabler color matching and there was not severe complications. Conclusion:The vascularized dermal fat flap provides an alternative to conventional forearm flap harvest, which enables primary donor site closure with reduced rates of delayed donor site healing. The vascularized dermal fat flap is a relatively reliable repair method for soft defects in Oral and Maxillary Area.

Fifty free flaps from the ear

Reconstruction of facial and intraoral defects is often challenging. Local pedicled flaps may not always be available and distant free flaps usually have suboptimal color match and texture for the facial area. The aim of this study was to assess whether auricular free flaps are a valid reconstructive option. Clinical data and outcomes of patients who underwent reconstruction with microsurgical flaps from the ear between 2011 and 2021 were analyzed. Patient demographic data, type of flaps, etiology, location and size of the defect, features of the pedicle and recipient vessels, complications, and additional surgeries were reviewed. Overall, 48 patients with 50 microsurgical flaps were identified. Thirty-one patients (65%) were men and 17 were (35%) women. The median age was 62 years. Among the 50 flaps, 26 (52%) were helix flaps, 20 (40%) were temporal artery posterior auricular skin flaps, and 4 (8%) were extended helix flaps. The nose was the most frequently reconstructed region (n=32, 64%), followed by the tongue (n=6, 12%), floor of the mouth (n=5%), lower eyelid (n=2%), and in one (2%) patient each, restoration of the upper eyelid, ear, larynx, esophagus, lower lip, and palate. The median follow-up was 74 months. Three flaps (6%) were lost, and the overall rate of complications was 46%. Surgical intervention was required in 7 (14%) cases. All cases healed with acceptable cosmesis. The ear is a valuable source of tissue for complex reconstructions of the face and intraoral regions. However, this technique is surgically demanding and should be reserved for selected cases.

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.