Color Grading Research Articles

Study on the correlation between trace elements and colorimetric parameters of natural blue sapphire

AbstractNatural blue sapphire is a gem species of corundum, which has high economic value due to its beauty and rarity. Color is the most important factor affecting the price of sapphire and mainly caused by trace elements. However, there is little quantitative data currently available to demonstrate the correlation between trace elements and colorimetric parameters of natural blue sapphire. In this study, the UV‐Vis‐NIR spectra and colorimetric parameters were collected by UV‐Vis‐NIR spectrophotometer while the chemical composition was analyzed by laser‐ablation inductively coupled plasma mass spectrometry. The results show that the content ratio of (FeOT + TiO2)/MgO has negative correlation with b* but positive correlation with Cab*, illustrating its obvious effect on the blue color saturation of natural blue sapphire. In addition, the existence of Cr can produce purple hue and the content of Cr shows positive correlation with hue‐angle hab only in the low range (5‐15 ppm), which implies the content of Cr has a limited influence on the hue of natural blue sapphire and the effect may be more complicated as the content of Cr increases above 15 ppm. This investigation can provide quantitative data for scientific color grading and additional applications of natural blue sapphire.

Early- and Middle-Phase Angioscopic Assessment of Arterial Healing Following Current Drug-Eluting Stent Implantation in Patients With Acute Coronary Syndrome.

Background: Drug-eluting stents (DESs) have been widely used for the treatment of acute coronary syndrome (ACS). However, there are few reports on early- and middle-phase arterial repair after DES implantation in ACS patients.Methods and Results: Coronary angioscopy (CAS) findings covering the early and middle phases (mean [±SD] 4±1 and 10±2 months, respectively) of arterial healing after second- and later-generation DES placement between May 2009 and January 2020 were extracted from the Kansai Rosai Hospital Cardiovascular Center database. Neointimal coverage (NIC), yellow color intensity, and the incidence of thrombus adhesion were compared between ACS and chronic coronary syndrome (CCS) in the early (54 stents of 47 lesions, 38 ACS patients; 86 stents of 70 lesions, 52 CCS patients) and middle (179 stents of 154 lesions from 136 ACS patients; 459 stents of 374 lesions from 287 CCS patients) phases. In the early phase, NIC, the incidence of thrombus adhesion (ACS, 39.1%; CCS, 38.0%), and maximum yellow color grade were similar between the 2 groups. In the middle phase, although the maximum yellow color grade was significantly higher in the ACS group (P=0.013), NIC and the incidence of thrombus adhesion (ACS, 24.6%; CCS, 23.4%) were similar in the 2 groups.Conclusions: Arterial healing assessment with CAS showed that NIC and the incidence of thrombus adhesion after DES implantation were similar between ACS and CCS patients.

Preliminary Study on Sapphire Color Grading Method Based on Automatic Clustering Algorithm of Color Space Features

Traditionally, the color grading of sapphire is mainly based on the naked eye judgment of the appraiser. This judgment standard is not clear enough, and the judgment result has a greater subjective influence, which affects the accuracy of the classification. In this study, the GEM-3000 ultraviolet-visible spectrophotometer was selected, and the color features of 180 sapphire samples were extracted and classified using the CIE1976 color space of the device. The Kmeans algorithm was used to cluster analysis of 140 samples, and the separability of the color space features of different color levels was verified, and the center sample of each color level was obtained. The Euclidean distance between the centers of the remaining 40 samples is calculated, and each color grade prediction label is determined, and the sapphire color is automatically classified based on this. The experimental results show that the accuracy of sapphire color classification using the above method is 97.5%, which confirms the effect and accuracy of the artificial intelligence method in sapphire color classification.

대학 영상 교육을 위한 룩업 테이블 활용 및 아날로그 필름 룩 구현 워크플로우

Color grading in the analog film era and the early days of digital video production meant only a very narrow range of image reprocessing due to technical limitations. However, the development of technology and the advent of high-performance digital cameras to capture images in Log or RAW formats have made the color grading stage in modern film post-production no longer an artistic choice but an essential step. This study suggests an alternative solution given the fact that the completeness of video production practice work by student on their first or second-year in the field of university video education is often insufficient due to their lack of technical understanding. Currently, filmmaking practice is conducted gradually for students in all grades in the video-related department curriculums of most universities, while in-depth education and color correction education practice on the post-production stage are conducted only for students on their third or fourth-year. However, these environmental constraints are not the result of a lack of understanding by film industry workers or film educators regarding the importance of post-production technology. They arise due to a lack of understanding of earlier concepts in film production, such as principal photography, lighting, and sound design, which should be prioritized on top of theoretical knowledge of media in order to ensure a sound understanding of post-production technology. Therefore, this paper aims to present the use of a lookup table workflow as a realistic alternative that can be applied to the film production practice of students early in their college years who will later learn in the full-scale post-production stage. In addition, by utilizing the LUT workflow for the creation of an analog film look in digital images as a visual example necessary during the research process, we intend to contribute through this study to the expansion of the selection of student film works, such as by reviving the look of specific time periods.

Artwork style transfer model using deep learning approach

Art in general and fine arts, in particular, play a significant role in human life, entertaining and dispelling stress and motivating their creativeness in specific ways. Many well-known artists have left a rich treasure of paintings for humanity, preserving their exquisite talent and creativity through unique artistic styles. In recent years, a technique called ’style transfer’ allows computers to apply famous artistic styles into the style of a picture or photograph while retaining the shape of the image, creating superior visual experiences. The basic model of that process, named ’Neural Style Transfer,’ has been introduced promisingly by Leon A. Gatys; however, it contains several limitations on output quality and implementation time, making it challenging to apply in practice. Based on that basic model, an image transform network was proposed in this paper to generate higher-quality artwork and higher abilities to perform on a larger image amount. The proposed model significantly shortened the execution time and can be implemented in a real-time application, providing promising results and performance. The outcomes are auspicious and can be used as a referenced model in color grading or semantic image segmentation, and future research focuses on improving its applications.

The Effects of Munsell Neutral Grey Backgrounds on the Colour of Chrysoprase and the Application of AP Clustering to Chrysoprase Colour Grading

Chrysoprase is a popular gemstone with consumers because of its charming apple green colour but a scientific classification of its colour has not yet been achieved. In this research, we determined the most effective background of the Munsell Chart for chrysoprase colour grading under a 6504K fluorescent lamp and applied an affinity propagation (AP) clustering algorithm to the colour grading of coloured gems for the first time. Forty gem-quality chrysoprase samples from Australia were studied using a UV-VIS spectrophotometer and Munsell neutral grey backgrounds. The results determined the effects of a Munsell neutral grey background on the observed colour. It was found that the Munsell N9.5 background was the most effective for colour grading in this case. The observed chrysoprase colours were classified into five groups: Fancy Light, Fancy, Fancy Intense, Fancy Deep and Fancy Dark. The feasibility of the colour grading scheme was verified using the colour difference formula DE2000.

Cloud Production Pipeline Using IMF, C4ID, and Open TimeLine IO

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Cloud-centric use of Interoperable Master Format (IMF), Open TimeLine input/output (IO) (OTLIO), and C4ID combines to transform production, post, mastering, and localization of content in today’s multiplatform and international distribution environment. By leveraging IMF, OTLIO, and other open source and standardized tools such as C4ID Cloud Identifier, a centralized cloud-based continuous master can be created. This continuous master can be constantly synchronized with work-in-progress in editing, visual effects, color grading, and sound mixing systems to provide a single centrally available point of collaboration for all parties in production, post, localization, and distribution. This method avoids the requirement for proprietary asset management or file types and allows creatives and engineers to use the tools they prefer and avoids repeatedly moving assets in and out of the cloud. Furthermore, it allows a paradigm shift in the localization and distribution master process, which can in turn allow delivery of a project almost instantly to any number of platforms, territories, and versions once it is complete. This workflow also permits sharing of conformed work-in-progress versions at any moment during the production/post/versioning life cycle without interrupting progress in any of these processes. This method also has side benefits such as total deduplication of assets, no vendor or tool lock-in for access to assets and the ability to link business systems to the content creation process, thus allowing order-to-delivery automation. Overall, this method offers benefits in terms of time, cost, operational effectiveness, and, most importantly, creativity. This benefits all types of delivery from movies to episodic, advertising, trailers, or any produced content targeting multiplatform, domestic, and international audiences. It also allows for the latest content trends such as branching storylines and audience interactive content to be stored and accessed in a nonproprietary way. The methodology described in this paper provides a step change in managing today’s content pipelines and future proofing for next-generation workflows</i> .

Performance Comparison of Colour Correction and Colour Grading Algorithm for Medical Imaging Applications

Different types of image acquisition devices render different measure of colour depending on the specification of devices; even a same device will give different values of colours rendered, taking at certain duration of times. Most of the researches nowadays have attempted to solve these limitations and the researches of colour correction algorithm has been evolved recently. Colour correction algorithm has been widely used in various fields such as food industry, medical imaging, forensic cyber applications, film industries etc. In medical imaging, researchers have considered colour correction as an essential part in their pre-processing step prior to diagnosis. There are various statistical methods in colour correction and colour grading algorithm being implemented nowadays and finding the best algorithm with high accuracy is non-trivial. This paper presents comparative analyses of colour correction techniques that combine colour correction and colour grading algorithm using conventional gamma correction, polynomial regression, and proposed polynomial regression with modified gamma Look-up Table (pgLUT). It has been observed that our proposed pgLUT colour correction algorithm outperformed the conventional methods by 16.5%.

Ageing as a method to increase bloom depth and improve retail colour in beef graded AUS-MEAT colour 4

Meat colour is an important attribute for consumer acceptance but there is an interval between colour grading and retail display. This experiment investigates the effect of time post-slaughter (5, 14 and 40 days) on colour and bloom depth (after 1 and 24 h) for beef carcasses graded AUS-MEAT colour 4 (MC 4). Sixteen carcasses were selected at grading, 8 carcasses were graded MC 4 and 8 as compliant colour (AUS-MEAT score 2 or 3). At 5 days post-slaughter, compliant loins had greater overall bloom depth and were more red than MC 4 loins. Bloom depth (24 h) increased with ageing time but reached maximum bloom at 14 days for both treatments. After ageing for 14 and 40 days, the bloom depth of MC 4 loin was no different to the 5 day aged compliant loins after 24 h on display. Colour at grading may not be a reliable measure of retail colour considering the changes post slaughter.

Video recoloring via spatial-temporal geometric palettes

Color correction and color grading are important steps in film production. Recent palette-based approaches to image recoloring have shown that a small set of representative colors provide an intuitive set of handles for color adjustment. However, a single, static palette cannot represent the time-varying colors in a video. We introduce a spatial-temporal geometry-based approach to video recoloring. Specifically, its core is a 4D skew polytope with a few vertices that approximately encloses the video pixels in color and time, which implicitly defines time-varying palettes through slicing of the 4D skew polytope at specific time values. Our geometric palette is compact, descriptive, and provides a correspondence between colors throughout the video, including topological changes when colors merge or split. Experiments show that our method produces natural, artifact-free recoloring.

Neuromuscular ultrasound (NMUS) O-NU001. Feasibility of shear wave elastography and high definition color in evaluation of carpal tunnel syndrome

Introduction . Diagnosis of carpal tunnel syndrome (CTS) is based on clinical findings and electrodiagnostic tests (EDT). However, EDT has high false negative rates, and the results often do not reflect the severity of symptoms. The aim of this study is to investigate the value of shear wave elastography (SWE) and high definition (HD) color in diagnosis and evaluation of symptom severity in CTS. Methods . The study prospectively enrolled 39 wrists from 23 patients with EDT-confirmed CTS, 15 wrists from 12 patients who have CTS symptoms without EDT abnormality and 28 wrists from 14 healthy volunteers. Cross-sectional area (CSA) and longitudinal diameter of median nerve were measured. SWE of median nerve at the wrist and midforearm were performed, and the ratio between them was calculated. SWE of abductor pollicis brevis (APB) and abductor digiti minimi (ADM) were also measured and the ratio was obtained. HD color was conducted in the longitudinal plane at carpal tunnel. Results . The CSA of the median nerve at the carpal inlet and longitudinal diameter were significantly larger for the EDT-confirmed CTS group compared to control group (13.21[11.28,17.23] vs 7.98[6.53,8.94]; p < 0.001, 2.77[2.41,3.08] vs 2.07[1.79,2.24]; p < 0.001). It also had significantly higher median nerve elasticity ratio (2.59[1.77,4.09] vs 1.61[1.32,1.94]; p = 0.007). HD color showed significantly higher grades in the former group (p = 0.004). In ROC analysis, a 1.97 cut-off value on SWE ratio revealed sensitivity, specificity, PPV, NPV of 74.4%, 78.6%, 82.9%, 68.8%, respectively (AUC: 0.796[0.687,0.905]). Inter-rater reliability was excellent for SWE measurements (ICC: 0.908(0.761,0.967)). There was no significant correlation of CSA, elasticity and HD color grade with clinical symptom scores. In comparison between the group of CTS patients without EDT abnormality and control group, the former had significantly larger CSA in carpal inlet and elasticity ratio (9.61[7.21,11.55] vs 7.98[6.53,8.94]; p = 0.011, 2.59[0.94,4.65] vs 1.61[1.32,1.94]; p = 0.009). Conclusion . SWE and HD color are helpful supportive tools in diagnosing CTS, especially in patients who have typical CTS symptoms but normal results in EDT.

Influencing Factor Analysis of the Hammer Price of Yellow Diamond Online Auction: A Case Study of Ali Auction Hammer Price

In this paper, the factors affecting the hammer price of yellow diamonds were explored and analyzed through the auction data of yellow diamonds from July to September 2019 of Ali Auction. After constructing a five-factor model including auction setting, item description, commodity attribution, buyer competition and bidding strategy, the relevant hypothesis was put forward, and the empirical test was carried out by using correlation analysis and multiple linear regression analysis. It was found that the mark-up range in auction setting, the weight and colour grade of the diamonds in commodity attribute, the bidding times in buyer competition and the jumping bid in bidding strategy all have significant effects on the hammer price. Other factors such as margin, the number of pictures, the status of the end of the auction, and the number of applicants etc. have no significant impact on the hammer price.

Using ACES Look Modification Transforms (LMTs) in VFX Environments &amp;#x2013; Part 2: Gamut Mapping

In modern moving image production pipelines, it is unavoidable to move the footage through different color spaces. Unfortunately, these color spaces exhibit color gamuts of various sizes. The most common problem is converting the cameras’ widegamut color spaces to the smaller gamuts of the display devices (cinema projector, broadcast monitor, computer display). So it is necessary to scale down the scene-referred footage to the gamut of the display using tone mapping functions [34].In a cinema production pipeline, ACES is widely used as the predominant color system. The all-color compassing ACES AP0 primaries are defined inside the system in a general way. However, when implementing visual effects and performing a color grade, the more usable ACES AP1 primaries are in use. When recording highly saturated bright colors, color values are often outside the target color space. This results in negative color values, which are hard to address inside a color pipeline. "Users of ACES are experiencing problems with clipping of colors and the resulting artifacts (loss of texture, intensification of color fringes). This clipping occurs at two stages in the pipeline: &lt;list list-type="simple"&gt; &lt;list-item&gt;- Conversion from camera raw RGB or from the manufacturer’s encoding space into ACES AP0&lt;/list-item&gt; &lt;list-item&gt;- Conversion from ACES AP0 into the working color space ACES AP1" [1]&lt;/list-item&gt; &lt;/list&gt;The ACES community established a Gamut Mapping Virtual Working Group (VWG) to address these problems. The group’s scope is to propose a suitable gamut mapping/compression algorithm. This algorithm should perform well with wide-gamut, high dynamic range, scene-referred content. Furthermore, it should also be robust and invertible. This paper tests the behavior of the published GamutCompressor when applied to in- and out-ofgamut imagery and provides suggestions for application implementation. The tests are executed in The Foundry’s Nuke [2].

Microwave Spectroscopy as a Potential Tool for Color Grading Diamonds

A diamond’s color grading is a dominant property that determines its market value. Its color quality is dependent on the light transmittance through the diamond and is largely influenced by nitrogen contamination, which induces a yellow/brown tint within the diamond, as well as by structural defects in the crystal (in rare cases boron contamination results in a blue tint). Generally, spectroscopic instrumentation (in the infrared or UV–visible spectral range) is used in industry to measure polished and rough diamonds, but the results are not accurate enough for precise determination of color grade. Thus, new methods should be developed to determine the color grade of diamonds at longer wavelengths, such as microwave (MV). No difference exists between rough and polished diamonds regarding stray light when the MW frequency is used. Thus, several waveguides that cover a frequency range of 3.95–26.5 GHz, as well as suitable resonator mirrors, have been developed using transmission/reflection and resonator methods. A good correlation between the S12 parameter and the nitrogen contamination content was found using the transmission/reflection method. It was concluded that electromagnetic property measurements of diamonds in the MW frequency range can be used to determine their nitrogen content and color grading. The MW technique results were in good agreement with those obtained from the infrared spectra of diamonds.

Integrating Machine-Learning-Based Operators in Visual Effects Toolsets

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Post-production workflows rely heavily on image processing and computer vision algorithms for the implementation of their visual effects (VFX) tools. In these fields, machine learning has been shown to be disruptive. By integrating the domain statistics from a given training data set, machine-learning-based operators may be more efficient at solving existing problems and may enable new problems to be solved, expanding the VFX toolset. In this study, we share our experience developing and integrating several machine-learning-based operators into software for the post-production industry. We will present a sky segmentation operator, a depth map estimation operator, and an operator to compute face geometric maps (UVs,<xref ref-type="fn" rid="fn1">^*</xref> depth, and normals) from sequences of images. More specifically, these operators consist of trained deep convolutional neural networks (DCNNs) taking as input an RGB color image and outputting the associated maps, that is, a matte, depth, normals, and/or UV maps. Such maps permit the application of many different effects to the input image during color grading, including beautification or even relighting of faces. These studies will serve as a case study to review and discuss the multiple challenges posed by the implementation, integration, and deployment of machine-learning-based operators into a VFX toolset</i> .

Elastosonographic features of the metacarpophalangeal joint capsule in horses

BackgroundCapsulitis leads to the release of inflammatory mediators in the joint, causing capsular fibrosis and osteoarthritis (OA). Strain elastosonography (SE) measures the elasticity of tissue by evaluating its strain in operator-dependent deformation. The aims of the study were to assess the feasibility, repeatability, and reproducibility of SE for imaging the distal attachment of the joint capsule (DJC) of metacarpophalangeal joints in sound horses (Group S) and in horses with metacarpophalangeal OA (Group P) and to evaluate differences in the elastosonographic patterns of these horses. After a whole lameness examination, fore fetlock DJCs were assigned to Group S and Group P and were thereafter examined by two operators using SE. Qualitative (i.e., colour grading score) and semi-quantitative (i.e., elasticity index (EI) and strain ratio (SR)) methods were used to evaluate the elastograms. The inter-rater reliability (IRR), intraclass correlation coefficient (intra-CC) and interclass correlation coefficient (inter-CC) were used to compare colour grading scores and the repeatability and reproducibility of EI and SR outcomes. The same parameters were compared between groups. P < 0.05 indicated a significant finding.ResultsForty-one horses were included: 11 were in Group S and 30 were in Group P (16 with bilateral OA, 8 with left OA and 6 with right OA). IRR outcomes ranged from good to excellent. For transverse and longitudinal ultrasound scans, the colour grading score of Group S was significantly higher than the metacarpophalangeal DJCs of Group P. Both Inter-CC and intra-CC were higher in Group S than in Group P, with values always > 0.8. Significative differences in EI and SR were detected between groups and between Group S and the affected limb of Group P; values were lower in Group S than in Group P.ConclusionsSE can be a useful technique for evaluating DJCs, with good repeatability and reproducibility. DJCs appear softer in sound horses.

Millimeter wave spectroscopy for evaluating diamond color grades

One of the most important parameters affecting the value of natural colorless diamonds is its light transparency, defined as its color grade. The regular range of color grades in the trade is denoted by alphabet letters in the range D-M, where D represents the best commercial quality. The color grade of diamonds is largely influenced by their nitrogen content (when nitrogen atoms substitute carbon atoms in the crystal) and can be determined from this property. Diamonds absorb electromagnetic radiation in the UV–visible as well as in the Infrared spectral range and therefore, their color grade is measured via spectroscopic light absorption in these frequency range. The electromagnetic properties of different polished diamonds having several nitrogen concentrations in the frequency range of 100–110 GHz (W band) have been studied. The results indicate that there is a good correlation between the amount of nitrogen impurities and the Free Spectral Range (FSR) parameter of a reflection signal, S11, in the antenna. From the study It is concluded that measuring the diamonds dielectric properties via spectroscopic analysis in the millimeter wavelength range, can determine the color grading. In addition, the FSR measurements were correlated well with the FTIR measurements. The methodology of the new color determination mode and a novel color estimate, based on the FSR vs the nitrogen correlation, has been tested on 26 diamonds with a success rate higher than 70%.

Observer variability study and method to implement observer categories for novel light source projection system

AbstractAs display technology advances in color gamut, the potential of experiencing higher degree of observer metamerism is more likely with narrow bandwidth stimuli display devices. In previous studies, it is confirmed that observer metamerism was introduced in soft proofing with monitor and color grading with projector scenarios, and also led to serious implications. Hence, it is desired to investigate whether laser‐based projection system would introduce observer metamerism compared to halogen‐based projection system. In this study, a two‐part experiment was designed and conducted. Experiment 1 was based on color patches and experiment 2 was based on test images. Intra‐observer and inter‐observer variability were calculated and analyzed. Both experiments had illustrated observer metamerism was introduced in laser‐based projection system. Comparison to CIE Standard Observers was also conducted for each experiment, and the results had suggested that the CIE Standard Observers were not suitable for laser‐based projection system. A new observer category was required at least for the group of observers participating the experiments. A quick method to transform the content from the CIE 1964 Standard Observer for color patches or the CIE 1931 Standard Observer for images has been established in experiment 1, and this quick method could help to facilitate the growth of personalized color management system.

Fourier-transform infrared spectroscopy for analysis of diamond materials of different origin

The study of impurity composition of diamond materials is an important element of their classification for use in various fields of science and technology. Many physical (thermal and electrical conductivity, optical purity), mechanical (hardness and strength) and aesthetic (color grade and clarity) properties of diamond depend on the presence of impurities in their structure; therefore, it is important to quickly and reliably determine each impurity in diamond. In this work, the method of FTIR spectroscopy is proposed as an express method for determining the impurity composition of diamonds. We examined three types of diamond materials: single crystal natural diamonds (before and after heat treatment), single crystal synthetic HPHT-diamonds and synthetic polycrystalline diamond CVD-films. We have established that the used technique allows to determine impurities in single crystals of natural and synthetic origin reliably and effectively, while the study of polycrystalline thin films is best performed using spectrophotometry.

Quantitative Validation of the Coronary Angioscopic Yellow Plaque with Lipid Core Burden Index Assessed by Intracoronary Near-Infrared Spectroscopy.

Aim: We aimed to validate the subjective and qualitative angioscopic findings by the objective and quantitative near-infrared spectroscopic (NIRS) assessment to compensate each other’s drawbacks. Methods: This is a single-center prospective observational study. Patients undergoing a planned follow-up coronary angiography after percutaneous coronary intervention were prospectively enrolled from January 2018 to April 2019. The major three vessels were examined by NIRS-intravascular ultrasound, followed by coronary angioscopic evaluation. Yellow color grade on angioscopy was classified into four grades (0, white; 1, slight yellow; 2, yellow; and 3, intensive yellow) at a location of maximal lipid core burden index over 4 mm [LCBI (4)] on NIRS in each vessel. Results: A total of 95 lesions in 44 patients (72.6±6.7 years, 75% male) were analyzed. LCBI (4) was significantly different among different yellow color grades by coronary angioscopy (ANOVA, p ＜0.001). Positive correlation was found between angioscopic yellow color grade and LCBI (4) (beta coefficient 164.8, 95% confidence interval 122.9–206.7; p ＜0.001). The best cutoff value of LCBI (4) to predict the presence of yellow plaque (yellow color grade ≥ 2) was 448 (sensitivity 79.3%, specificity 69.7%, C-statistic 0.800, 95% confidence interval 0.713–0.887, p ＜0.001). Conclusion: The qualitative angioscopic assessment was objectively validated by the quantitative NIRS evaluation, which would be helpful for the reinterpretation of the existing evidences of both imaging modalities.