Standard Color Card Research Articles

Machine vision-based online detection method for color characteristics of cobalt extraction solution

Cobalt, as a rare metal, plays an important role in strategic resources due to its physical, chemical, and mechanical properties in applications. In order to achieve automatic control of the cobalt extraction process, it is necessary to conduct online detection of the color characteristics of the cobalt extraction solution. Unfortunately, due to the lack of online automatic detection methods for the color of cobalt extraction solution, the automatic control of the extraction process has not yet been achieved. Currently, the color of cobalt extraction solution needs to be observed and judged by operators based on experience. This will result in significant detection errors and time lag. To change this situation, an online detection method for color features of cobalt extraction solution based on machine vision is proposed in this article. Firstly, we establish a real-time image acquisition environment for detecting object colors, and then use the Gaussian filters and K-means algorithm to denoise and segment the image. In order to correct color distortion in images caused by ambient light, we measure the color feature values of a set of standard color cards using the machine vision system and a standard spectrophotometer. Based on this test data, we establish chromaticity correction models for the extraction solution using back propagation (BP) network and radial basis function (RBF) network, respectively. The models can correct the color characteristic values of the extraction solution, overcome environmental interference, and thus obtain more accurate color characteristic values of the extraction solution. The established model can be used for online automatic color detection of cobalt extraction solution. The modeling results indicate that in the established color measurement environment, the RBF network model outperforms the BP network model in color feature detection accuracy.

Design of printing ink spectral collection system and research on ink proportion prediction method

In spectral-based ink content measurement, improving the accuracy of the spectral collection system and reducing the algorithm complexity of the ink content measurement model are important aspects of research. This study designs a spectral collection system with an M-type Czerny–Turner optical path structure, uses a third-order polynomial fitting method for calibration analysis, collects the spectral of the standard color card and denoises it through Savitzky–Golay convolution smoothing, and establishes a functional relationship between the spectral and the logarithm of ink content. Uninformative Variable Elimination (UVE) and Competitive Adaptive Reweighting Sampling are used to perform comparative analysis on feature wavelength extraction, and a prediction model for printing ink content is established. Experimental results show that the R2 of ink C, ink M, and ink Y are 0.9981, 0.9975, and 0.9892, respectively, and the root mean square error is 0.0134, 0.0153, and 0.0317, respectively, showing good performance in ink prediction accuracy.

Dual-mode detection of 2,6-pyridinedicarboxylic acid based on the enhanced peroxidase-like activity and fluorescence property of novel Eu-MOFs.

2,6-Pyridinedicarboxylic acid (DPA) is a significant biomarker of anthrax, which is a deadly infectious disease for human beings. However, the development of a convenient anthrax detection method is still a challenge. Herein, we report a novel europium metal-organic framework (Eu-MOF) with an enhanced peroxidase-like activity and fluorescence property for DPA detection. The Eu-MOF was one-step synthesized using Eu3+ ions and 2-methylimidazole. In the presence of DPA, the intrinsic fluorescence of Eu3+ ions is sensitized, the fluorescence intensity linearly increases with an increase in DPA concentration, and the fluorescence color changes from blue to purple. Simultaneously, the peroxide-like activity of the Eu-MOF is enhanced by DPA, which can promote the oxidation of TMB to oxTMB. The absorbance values increase linearly with DPA concentrations, and the colorimetric images change from colorless to blue. The dual-mode detection of DPA has good sensitivity with a colorimetric detection limit of 0.67 μM and a fluorescent detection limit of 16.67 nM. Moreover, a simple detection method for DPA was developed using a smartphone with the RGB analysis system. A portable kit with standard color cards was developed using paper test strips. The proposed methods have good practicability for DPA detection in real samples. In conclusion, the developed Eu-MOF biosensor offers a valuable and general platform for anthrax diagnosis.

True-Color Reconstruction Based on Hyperspectral LiDAR Echo Energy

With the development of remote sensing technology, the simultaneous acquisition of 3D point cloud and color information has become the constant goal for scientific research and commercial applications in this field. However, since radar echo data in practice refer to the value of the spectral channel and its corresponding energy, it is still impossible to obtain accurate tristimulus values of the point through color integral calculation after traditional normalization and multispectral correction. Furthermore, the reflectance of the target, the laser transmission power and other factors lead to the problems of no echo energy or weak echo energy in some bands of the visible spectrum, which further leads to large chromatic difference compared to the color calculated from the spectral reflectance of standard color card. In response to these problems, the hyperbolic tangent spectrum correction model with parameters is proposed for the spectrum correction of the acquired hyperspectral LiDAR in the 470–700 nm band. In addition, the improved gradient boosting decision tree sequence prediction algorithm is proposed for the reconstruction of missing spectrum in the 400–470 nm band where the echo energy is weak and missing. Experimental results show that there is relatively small chromatic difference between the obtained spectral information after correction and reconstruction and the spectrum of standard color card, achieving the purpose of true color reconstruction.

Color Characteristics of Four-Color Samples in the Foggy Environment under Different Lighting Conditions

Traffic signs should provide clear signals for drivers and passengers under various environmental and geographic conditions. In foggy weather, the signal will be disturbed due to light scattering, which will cause obstacles to recognition. This study simulated a foggy environment in the laboratory, used a standard color card as the target, and introduced a colorimeter to record the color coordinates, then calculated the color difference and analyzed the four-color samples’ color properties in different lighting conditions. We found that as the relative visibility increases, the chromatic aberration of the sample will gradually decrease under different lighting conditions and reach zero when the relative visibility is higher than 70%. We found that the green and blue samples have better color coordinate retention capabilities than the fog’s red and yellow. We compared all tested light sources’ performance, and the results showed that 3000K LED and incandescent lamps are better than other light sources. This study will provide a data basis for the study of traffic safety and accident prevention.

A novel profuse color card for convenient visual determination of iodide in human urine based on catalytic oxidation reaction

In this work, we reported a novel and convenient profuse color card for naked eye determination of iodide (I−) in urine using chromogenic substrate 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). I− catalyzed the oxidation of ABTS by peroxyacetic acid causing ABTS to yield cyan product ABTS+ with a new absorption peak at 730 nm. The addition of rose-red dye rhodamine B (RhB) changes the overall color of the solution from pink to purple and finally to blue, which makes the solution multicolor and easy to distinguish. A good linear relationship for I− was obtained ranging from 10.0 to 500.0 μg/L with the detection limit of 9.2 μg/L. Importantly, the sensor can semi-quantitatively estimate the concentration of I− in human urine with naked eye through the standard color card and assess the deficiency or excess of iodine in human body. The proposed profuse color card opens up a new colorimetric method for the rapid, simple and reliable determination of I− in clinic, and has promising applications in developing assay kit for the clinical diagnosis of I− in urine.

Phase-measuring profilometry of colored objects based on color coding and sinusoidal correction

To improve the phase-measuring profilometry measurement speed, phase-shifted fringes can be encoded into color channels. However, for colored objects, the intensity of the fringes in each channel is affected by surface texture. Therefore, a measurement method based on color coding and sinusoidal correction is proposed. First, two color images are encoded. The red (R) and blue (B) channels for the first image and the green (G) channel for the second image are used in a three-step phase-shifting process. Meanwhile, the G channel of the first coded image and the R and B channels of the second coded image are corresponding solid colors. Two color-coded images are projected onto the object’s surface, and the CCD captures the modulated deformed fringe pattern. After decoupling, the channels of the images are separated, the pure color channels are extracted, and the reflectivity of each point on the object surface in the RGB channels is calculated. Then, the intensity of the phase-shifted fringes in the two images is corrected by the calculated reflectivity. A 24-color standard color card and color lion mask were used to verify the method. Compared with the traditional color coding method, we were able to reduce the influence of color texture and obtain better results.

Accurate device-independent colorimetric measurements using smartphones.

Smartphones provide an ideal platform for colorimetric measurements due to their low cost, portability and image quality. As with any imaging-based colorimetry system, ambient light and device variations introduce error which must be dealt with. We propose a novel processing method consisting of a one-time calibration stage to account for inter-phone variations, and an innovative use of ambient light subtraction with image pairs to account for variation in ambient light. Data collection is kept very simple, making it particularly useful for use in the field, since nothing additional is required in the images. Ambient subtraction is first demonstrated for a range of colors and phones (Samsung S8 and LG Nexus 5X), and the Subtracted Signal to Noise Ratio (SSNR) is defined as a metric for assessing whether an image pair is appropriate at the time of image capture. The experimentally determined SSNR threshold below which to suggest retaking the images is 3.4. The classification accuracy for results using the proposed calibration pipeline is then compared to the simplest image metadata-based alternative and is found to be greatly superior. Finally, a custom colorcard is shown to improve the accuracy of device-independent results for known smaller ranges of colors over a standard colorcard, making this a possible application-specific modification to the overall processing pipeline.

Effects of Dietary Protein and Carbohydrate Levels on Gonad Index, Composition, and Color in the Purple Sea Urchin Strongylocentrotus purpuratus

AbstractUnderstanding the nutritional requirements of the purple sea urchin Strongylocentrotus purpuratus is essential for producing suitable formulated diets and promoting its aquaculture in Mexico. Protein and carbohydrates are required components for gonad growth in sea urchins, yet their levels and effects on gonad composition and color have not been determined for this species. The effects of dietary protein and carbohydrates on gonad index, consumption, proximate content, and color were investigated in S. purpuratus in a 12‐week experiment, from April to June 2015. Sea urchins were collected from Arbolitos Bay in Ensenada, Baja California, Mexico, and fed diets that contained three protein levels (300, 230, and 170 g/kg) and two carbohydrate levels (420 and 500 g/kg). All diets significantly increased gonad index, but individuals that were fed a diet with 300 g/kg of protein and 500 g/kg of carbohydrate had the highest gonad index. Dietary protein had a significant effect on lipid storage, whereas protein and nitrogen‐free extract storage had no significant relationship with dietary protein or carbohydrate. Differences between gonad color and the standard color cards indicated that S. purpuratus gonads tended to be closer to an orange‐yellow color. This study indicates that S. purpuratus will have increased gonad index values at all protein and carbohydrate quantities that were tested in this study. However, gonad coloration is more suitable with a diet containing 230 g/kg of protein and 500 g/kg of carbohydrates.

Effects of water depth and substrate color on the growth and body color of the red sea cucumber, Apostichopus japonicus

Three color variants of the sea cucumber, Apostichopus japonicus are recognized, the red one is highly valued in the market. When the red variant is cultured in ponds in China, its body color changes from red to celadon in 3–6 months. The effects of water depth and substrate color on the growth and body color of this animal were investigated. Juveniles of red A. japonicus were cultured in cages suspended at a range of water depths (20, 50, 100, 150 and 200 cm). The specific growth rate of red sea cucumbers was significantly higher in animals cultured at deeper water layers compared with those grown at shallowers. Body weights were greatest for sea cucumbers cultured at a depth of 150 cm and their survival rates were highest at a depth of 200 cm. A scale to evaluate the color of red sea cucumbers (R value) was developed using a Pantone standard color card. All stocked animals in the 9-month trial retained a red color, however the red body color was much more intense in sea cucumbers cultured at shallower depths, while animals suspended in deeper layers became pale. In a separate trial, A. japonicus were cultured in suspended cages with seven different colored substrates. Substrate color had a significant effect on the growth and body-color of red A. japonicus. The yield were greatest for A. japonicus cultured on a yellow substrate, followed by green > white > orange > red > black and blue. All sea cucumbers in the 7-month trial retained a red color, although the red was most intense (highest R value) in animals cultured on a blue substrate and pale (lowest R value) for animals cultured on a green substrate.

A Printer Point Set Gamut Model Based on BP Neural Network

In the color management system, device gamut is an important prerequisite for effective color management. Currently, device gamut is described by convex hull model. In this method, electronic standard color card is output on certain media, the chromatic values of the color blocks of the color card are measured as vertices to build the three-dimensional space of convex hull. In spite of the simplicity of the description method in manipulation, the factors that can't be ignored are as the following, the relatively representative of the color blocks on the color card and the device gamut has something to do with the factors such as device feature, as well as the surrounding light and device parameters. Near the edge of the convex hull, the device limit color points perhaps locate inside and outside the edge of the convex hull, so the convex hull model can't describe the device gamut exactly. In the research, based on mapping relation of digital image pixel value and its corresponding printed color, printer characterization model is established based on BP neural network with exactitude to a perfect certainty. Then, digital image pixel values with kinds of intervals are taken to calculate the color point sets by the printer characterization model, and the device gamut could be described by the color points sets. By visual method, both the convex hull model and the point set model are compared. The experiment shows that the point set models describe the printer gamut more precise than the convex hull model.

Color grading of beef fat by using computer vision and support vector machine

Machine vision and support vector machine (SVM) were used to determine color scores of beef fat. One hundred and twenty-three of beef rib eye steaks were selected to sensory evaluation and image processing. After fat color score was assigned to each steak by a five-member panel according to the standard color cards, images were acquired for each steak. The subcutaneous fat was separated from the rib eye by using a sequence of image processing algorithms, boundary tracking, thresholding and morphological operation, etc. Twelve features of fat color (six features were extracted from the subcutaneous fat images and the other six were calculated) were used as input for SVM classifiers. The best SVM classifier was chosen according to percentage of correct classified samples based on the training set and then was validated by a nondependent test set. The proposed SVM classifier achieved the best performance percentage of 97.4%, showing that the machine vision combined with SVM discrimination method can provide an effective tool for predicting color scores of beef fat.

Simple methods for rapid determination of sulfite in food products

Two simple methods for sulfite determination in food products were proposed. The modified para-rosaniline (PRA)-formaldehyde method showed a much broader linear range (0.05–5.0 mg l −1 as SO 2) than the commonly used procedure for the sulfur dioxide detection in the atmosphere (0.05–1.0 mg l −1 as SO 2). By using a standard reference color card, this method only needed 5 min to complete a test. The 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) method was another good alternative for rapid determination of sulfite since it only needed one main reagent and the method was robust and easy to operate with the linear range of 0.10–4.3 mg l −1 as SO 2. When applying to real food samples, the DTNB method had good recoveries for all the tested samples and the results agreed well with those obtained by the official iodometric titration. The modified PRA-formaldehyde method worked well with all the tested dried food products, though matrix effect of sulfite binding was observed for the beer samples. Thus, the modified PRA-formaldehyde method has advantages of sensitivity and rapidity, but the DTNB method offers a wider range of applications. Both methods provided practical ways for in situ determination of sulfite by non-professional operators with the modified PRA-formaldehyde method suited for food samples with less sulfite binding problems.

Appearance of Object Colors in Dense Fog. Shift of Perceived Munsell Value and Chroma.

It is a well-known fact that the visual characteristics of humans are heavily affected by differential visual environments. This paper describes an experiment in which we examined how object colors look like in a dense fog. Seven male subjects with normal color vision contributed to the evaluation of their perception of object colors in the dense fog. The subjects were asked to match the colors of ten standard color cards, as perceived in the dense fog, with Munsell color sheets at hand. The results of our experiment made it clear that the apparent chroma and value tends to reduce with increased density of the fog in any of the color chips. We believe that these experimental results will come to provide useful basic data not merely in the fundamental research relating to the vision but in any such practical aspect as the countermeasures for traffic visual environments in a dense fog.

カラーマッチング法を用いた物体色の見え方評価 濃霧中における

Our visual characteristics are affected by our visual environment. In this experiment, we examined how object colors are perceived in dense fog. Seven male subjects with normal color vision were asked to evaluate their perception of object colors in dense fog. The subjects' task was to match the apparent color of ten standard-color cards in dense fog to the Munsell color. In fog, the subjects' ability to determine colors decreased dramatically both in the chroma and value. That is, their color perception shifted from the perception of chromatic colors to that of achromatic colors. Our results can contribute to research of color perception in visual environments that include fog.

Considerations on new primaries for high definition television

A constant-luminance-coding (CIELAB) codec is presented for high-definition TV (HDTV) use that offers the possibility of enlarging the reproducible color TV spectrum by selecting a new set of primary colors. Tests on a BBC standard color card showed that this type of processing gives full flexibility for the choice of receiver and camera primaries and transparency for the transmission of all real surface colors. Subjective tests were carried out to investigate the importance of a wider color spectrum and the acceptability of CIELAB coding in a compatible HD-MAC system. It was found that more saturated primaries help to minimize calorimetric distortions if CIELAB coded signals are decoded by a conventional decoder.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Chromogenesis by Staphylococcus aureus and typing according to pigmentation.

Abstract The possibility of typing Staphylococcus aureus strains according to the color of colony pigments has been explored by a number of practical experiments. A technique has been developed for measuring the shade and intensity of pigments by using standard color cards and the results have been compared with those of phage typing and antibiograms. The data which were obtained from epidemics and isolated clinical infections illustrate situations in which strains were readily identified by pigment variations alone by the use of 2 or, in some instances, 3 methods. Results obtained by the pigment method are fairly comparable with those from phage typing and antibiograms when one considers outbreaks with only a few strains involved. On the other hand, when numerous strains are involved, analysis by this method may prove too insensitive. Experiments have shown that the intensity of color production decreases when the cultures are stored on stock culture agar in sealed test tubes. The decrease is stepwise, beginning after 5 to 12 months of storage. It is not synchronous in otherwise identical strains and, therefore, it seems to be influenced by factors which are not yet controllable. The method described therefore can be used only with strains recently isolated from their sources. However, this method may be convenient for screening, as it is simple, inexpensive, and relatively easy to standardize. Used together with antibiotic sensitivity tests, it should make a fairly good strain identification possible by most clinical bacteriology laboratories.

Spectrophotometric and Colorimetric Determination of the Colors of the TCCA Standard Color Cards

The color cards of the Textile Color Card Association of the United States are widely used in the textile and allied industries and by many procuring agencies of the federal government. The Textile Color Card Association issues both seasonal and standard color cards. The seasonal cards provide a color forecasting service to textile manufacturers and promote color coordination among the trades; the standard cards present colors for which there is a popular and continuing demand. Most important of the color cards is the Standard Color Card of America, the current ninth edition containing 216 colors. Pre-eminent among the many special sets of color cards issued by the Association for use of the federal government is the United States Army Color Card showing 22 official colors for the arms and services. The specification of the colors of the Ninth Edition Standard Color Card and the United States Army Color Card has been undertaken for the purpose of correlating these textile standards with American War Standard Z44—1942 for the specification and description of color. The 238 samples comprising these color cards have been examined by basic spectrophotometric and colorimetric procedures. From this study there have been found daylight reflectance, Y, chromaticity coordinates (x, y), Munsell renotations, and ISCC-NBS color designations for these samples as recommended by American War Standard Z44—1942. Since more than half of these textile standards are fluorescent, and since existing spectrophotometers are not suited to the evaluation of such samples, considerable reliance has been placed on quantitative colorimetric and photometric comparisons with the Munsell color standards, both by means of a chromaticity-difference colorimeter and by the Martens photometer. As a closing check Munsell book notations of these textile standards have been obtained by a direct visual comparison with the color scales of the Munsell Book of Color.

Spectrophotometric and colorimetric determination of the colors of the TCCA standard color cards

The color cards of the Textile Color Card Association of the United States are widely used in the textile and allied industries and by many procuring agencies of the federal government. The Textile Color Card Association issues both seasonal and standard color cards. The seasonal cards provide a color forecasting service to textile manufacturers and promote color coordination among the trades; the standard cards present colors for which there is a popular and continuing demand. Most important of the color cards is the Standard Color Card of America, the current ninth edition containing 216 colors. Pre-eminent among the many special sets of color cards issued by the Association for use of the federal government is the United States Army Color Card showing 22 official colors for the arms and services. The specification of the colors of the Ninth Edition Standard Color Card and the United States Army Color Card has been undertaken for the purpose of correlating these textile standards with American War Standard Z44—1942 for the specification and description of color. The 238 samples comprising these color cards have been examined by basic spectrophotometric and colorimetric procedures. From this study there have been found daylight reflectance, Y, chromaticity coordinates (x, y), Munsell renotations, and ISCC-NBS color designations for these samples as recommended by American War Standard Z44—1942. Since more than half of these textile standards are fluorescent, and since existing spectrophotometers are not suited to the evaluation of such samples, considerable reliance has been placed on quantitative colorimetric and photometric comparisons with the Munsell color standards, both by means of a chromaticity-difference colorimeter and by the Martens photometer. As a closing check Munsell book notations of these textile standards have been obtained by a direct visual comparison with the color scales of the Munsell Book of Color.