CIELAB Color Space Research Articles

CMYK-CIELAB Color Space Transformation Using Machine Learning Techniques

In this work four different machine learning approaches have been implemented to perform the color space transformation between CMYK and CIELAB color spaces. We have explored the performance of Support-Vector Regression (SVR), Artificial Neural Networks (ANN), Deep Neural Networks (DNN), and Radial Basis Function (RBF) models to achieve this color space transformation, both AToB and BToA direction. The data set used for this work was FOGRA53 which is composed of 1617 color samples represented both in CMYK and CIELAB color space values. The accuracy of the transformation models was measured in terms of ΔE* color difference. Moreover, the proposed models were compared, in practical terms, with the performance of the standard ICC profile for this color space transformation. The results showed that, for the forward transformation (CMYK to CIELAB), the highest accuracy was obtained using RBF. While, for the backward transformation (CIELAB to CMYK), the highest accuracy was obtained with DNN.

Effects of tooth bleaching protocols assisted by Er,Cr:YSGG and diode (980 nm) lasers on color change of resin-based restoratives.

To evaluate color change of three resin-based restorative materials after two laser-assisted in-office tooth bleaching protocols using Er,Cr:YSGG and diode (980 nm) lasers. A nanohybrid composite resin (EP), a Bis-GMA free composite resin (EPBio) and a resin-matrix CAD-CAM ceramic (HC) were tested. Ninety specimens were prepared and stored in artificial saliva. Group 1 received an in-office bleaching treatment using 40% H2 O2. The same bleaching procedure was assisted by Er,Cr:YSGG laser in Group 2 and by a diode laser (980 nm) in Group 3. Color measurements were performed using a double-beam UV-Vis spectrophotometer at four time intervals (before, 24 h, 15 and 30 days), converted to L*, a*, and b* units of the CIELAB color space and assessed on the basis of 50:50% acceptability (ΔΕab *=2.7 and ΔΕ00 =1.77) and 50:50% perceptibility (ΔΕab *=1.2 and ΔΕ00 =0.81) thresholds. Three-way ANOVA with repeated measurements was used for statistical analysis of the data. Color and whiteness changes did not exceed the established 50:50% acceptability thresholds. EP presented the highest color change after the bleaching followed by EPBio and HC (p ≤ 0.05). Three-way ANOVA revealed that type of material and time interval significantly affected color change (p ≤ 0.001). The tested bleaching treatments assisted by Er,Cr:YSGG and diode (980 nm) lasers did not induce unacceptable color and whiteness changes in the resin-based restorative materials. The tested Er,Cr:YSGG and diode (980 nm) laser-assisted tooth bleaching protocols which may be recommended to accelerate the clinical procedures cannot affect the color of the existing resin-based restorations in case they are accidentally exposed on the bleaching gel and laser irradiation.

Biological parameters, discolouration and radiopacity of calcium silicate‐based materials in a simulated model of partial pulpotomy

To analyse the discolouration, radiopacity, pH and calcium ion release of Biodentine (BD), Bio-C repair (BCR) and Bio-C temp (BCT), as well as their biological effects on human dental pulp cells (hDPCs). Sixty-four extracted bovine incisors were prepared to simulate crown fractures with pulp exposure and open root apex. The roots were filled using a mixture of agar and blood (control), and BD, BCR or BCT were placed over this mixture. Colour assessment analyses of the samples were performed before and immediately after material insertion and repeated at 30 and 90days, using a spectrophotometer. The colour change of each specimen was evaluated at the crown and calculated based on the CIELab colour space. Digital radiographs were acquired for radiopacity analysis. hDPCs were placed in contact with different dilutions of culture media previously exposed to such materials and tested for cell viability using the MTT assay. The pH and calcium ion release of all materials were measured after 24h; the data were assessed using one-way analysis of variance (ANOVA). Cell viability was analysed by two-way ANOVA. Differences in colour parameters and wound-healing data were assessed by two-way repeated measures ANOVA (α=0.05). Tukey's and Dunnett's tests were used to compare the experimental groups with the control group. BCR had grater radiopacity and smaller colour alteration (ΔEab/ΔE00) than the other materials tested (p<.005; p<.001). No significant differences in pH were found amongst the tested materials (p>.05). BCT was associated with the largest release of calcium ions (p<.0001). BD had cell viability similar to that of the control at the lowest dilutions, and BCR was similar to that of the control, regardless of the dilution tested (p>.05). BCT had a lower percentage of viability than that of the control at all tested dilutions (p<.0001). Cell migration rates in BD and BCR were similar to those in the control group after 24h and 48h (p>.05), whilst BCT had larger voids than the control in both periods (p<.0001). BCR, BCT and BD were associated with tooth discolouration. BCR had the lowest staining values, the highest radiopacity and viability greater than 80% hDPCs.

Photodegradation of Unmodified and Thermally Modified Wood Due to Indoor Lighting

Considering interior applications, sunlight, both direct through open window and through window glass, and artificial lighting are the main sources of radiation possessing sufficient energy to trigger photodegradation processes in wood. LED lamps, which emit mostly visible light, are becoming the dominant artificial light source in various interiors. In the present study, photodegradation of thermally modified (TM) and unmodified (UM) ash (Fraxinus excelsior), aspen (Populus tremula), and pine (Pinus sylvestris) due to exposure to UV radiation and LED lamps was evaluated and compared by analysing wood discolouration (CIELAB colour space), changes in reflectance and FTIR spectra, and formation of water-soluble components. The results show that, apart from UV radiation, LED lamps may cause considerable photodegradation of both TM and UM wood resulting in visually perceptible colour change, alteration in chemical structure and formation of water-soluble components. Improved photo-stability was observed for TM wood exposed to UV radiation, while even more changes in FTIR spectra were detected for TM than UM wood in the experiment with LED lamps. Comparing TM and UM wood, the changes due to photodegradation were quite similar for TM wood of all species while significant differences were observed in the case of UM wood.

Color changes in beef meat during pan cooking: kinetics, modeling and application to predict turn over time

The kinetics of heat-induced color changes in beef meat was determined and implemented in a numerical model for double-sided pan cooking of steak. The CIELab color space was used to obtain the lightness (coordinate L^*) and the reddish tone (coordinate a^*) of the cooked meat. L^* was the CIELab coordinate that contributed the most to the change in the absolute color. Two response surfaces were found to describe the evolution with time and temperature of both color coordinates, L^* and a^*. The model results were successfully verified with experimental data of the two coordinates along the thickness of the meat for three degrees of cooking. The Root-Mean-Squared Errors (RMSE) for coordinate L^* were 5.17 (very rare), 2.02 (medium rare) and 3.83 (done), and for coordinate a^* 1.44 (very rare), 1.26 (medium rare) and 0.89 (done). The applicability of the model for practical cooking purposes was illustrated by determining the optimum turn over time to achieve a similar color profile on both sides of the meat. The turn over time depended on the desired degrees of cooking, and were comprised between one-half and two-thirds of the final cooking time, increasing from very rare cooking degree to done cooking degree.

No-reference stereoscopic image quality assessment using quaternion wavelet transform and heterogeneous ensemble learning

As the demand for high-quality stereo images has grown in recent years, stereoscopic image quality assessment (SIQA) has become an important research area in modern image processing technology.In this paper, we propose a no-reference stereoscopic image quality assessment (NR-SIQA) model using heterogeneous ensemble learning ‘quality-aware’ features from luminance image, chrominance image, disparity and cyclopean images via quaternion wavelet transform (QWT). Firstly, luminance image and chrominance image are generated by CIELAB color space as monocular perception, and the novel disparity and cyclopean images are utilized to complement with monocular information. Then, a number of ‘quality-aware’ features in the quaternion wavelet domain are discovered, including entropy, texture features, energy features, energy differences features and MSCN coefficients of high frequency sub-band. Finally, a heterogeneous ensemble model via support vector regression (SVR) & extreme learning machine (ELM) & random forest (RF) is proposed to predict quality score, and bootstrap sampling and rotated feature space are used to increase the diversity of data distribution. Comparing with the state-of-the-art NR-SIQA models, experimental results on four public databases prove the accuracy and robustness of the proposed model.

Effect of Partial Replacement of Soybean with Chickpea to the Nutritional and Textural Properties of Tofu

&#x0D; Abstract— Tofu is an oriental food that originated from China and later became a traditional cuisine in many South East Asia Countries, e.g. Indonesia, Singapore, and Thailand. The tofu was made by coagulating soy milk with salt to form curds, which further compress to form a solid block. Tofu usually uses soybeans as the main ingredients; however, in this experiment, the soybeans were partially replaced with chickpeas to increase the amount of dietary fibre and reduce fat levels in the final products. The tofu was made of soybean and chickpea at a ratio of 100:0 (control), 90:10, 80:20 and, 70:30. The products were evaluated based on their nutritional contents (crude protein, crude fat, and crude fibre), and textural properties using Texture Profile Analysis. Some analytical parameters, such as pH, moisture content, and colour were also studied. Partial replacement of soybean with chickpea decreased overall crude protein and fat content, whereas increased crude fibre. The presence of chickpea in the blends, up to 30% (w/w), had affected the tofu curd's protein stability, lowered their pH, and moisture content. A denser tofu curd was obtained by adding more chickpea to the product. The 70:30 blend has the highest hardness value compared to the other formulations. This low soy content mixture, however, can not produce a cohesive and springy tofu gel. The CIELAB colour space of the soybean/chickpea tofu cubes records a trend of increase in redness and yellowness values for tofu with chickpea.

Yellow Pigment Powders Based on Lead and Antimony: Particle Size and Colour Hue.

This paper reports the results of particle size analysis and colour measurements concerning yellow powders, synthesised in our laboratories according to ancient recipes aiming at producing pigments for paintings, ceramics, and glasses. These pigments are based on lead and antimony as chemical elements, that, combined in different proportions and fired at different temperatures, times, and with various additives, gave materials of yellow colours, changing in hues and particle size. Artificial yellow pigments, based on lead and antimony, have been widely studied, but no specific investigation on particle size distribution and its correlation to colour hue has been performed before. In order to evaluate the particle size distribution, segmentation of sample data has been performed using the MATLAB software environment. The extracted parameters were examined by principal component analysis (PCA) in order to detect differences and analogies between samples on the base of those parameters. Principal component analysis was also applied to colour data acquired by a reflectance spectrophotometer in the visible range according to the CIELAB colour space. Within the two examined groups, i.e., yellows containing NaCl and those containing K-tartrate, differences have been found between samples and also between different areas of the same powder indicating the inhomogeneity of the synthesised pigments. On the other hand, colour data showed homogeneity within each yellow sample and clear differences between the different powders. The comparison of results demonstrates the potentiality of the particle segmentation and analysis in the study of morphology and distribution of pigment powders produced artificially, allowing the characterisation of the lead and antimony-based pigments through micro-image analysis and colour measurements combined with a multivariate approach.

Spectral sensitivity of the discoloration of Historical rag paper

This paper discusses the spectral sensitivity of the discoloration of historical rag paper simultaneously affected by Relative Humidity (RH) and Oxygen concentration [O2] in the ambient environment. Sacrificial samples were degraded using narrowband radiation sources centred at 450 nm, 525 nm, and 625 nm in combinations of RH and [O2] at two levels: 0% [O2] and 70% RH, 21% [O2] and 70% RH, 0% [O2] and 20% RH, and 21% [O2] and 20% RH. Diffuse reflectance was measured before and during the degradation experimental runs. Consistent qualitative results were obtained for the change in reflectance and the change in tristimulus total color change in CIELAB color space. In both cases, the increase of discoloration was modelled logarithmically over time. Among the three factors investigated in this research, wavelength of the radiation (Λ) was found to have the strongest effect. The radiation at 450 nm induced the most and fastest discoloration whereas the radiation at 625 nm induced the least and slowest discoloration. This spectral dependence was likely to be related to the photo energies at different wavelengths, but other factors were found to have played a role. Further analyses revealed that the main effects and the effects of the interactions between [O2] and Λ and between RH and Λ on the discoloration of historical rag paper were statistically significant. It suggests that managing the spectral power distribution of the radiation source can be crucial in the collection management.

Comparative Analysis Of Efficient Image Segmentation Technique For Text Recognition And Human Skin Recognition

Computer Vision and Pattern Recognition is one of the most interesting research subject on computer science, especially in case of reading or recognition of objects in realtime from the camera device. Object detection has wide range of segments, in this study we will try to find where the better methodologies for detecting a text and human skin. This study aims to develop a computer vision technology that will be used to help people with disabilities, especially illiterate (tuna aksara) and deaf (penyandang tuli) to recognize and learn the letters of the alphabet (A-Z). Based on our research, it is found that the best method and technique used for text recognition is Convolutional Neural Network with achievement accuracy reaches 93%, the next best achievement obtained OCR method, which reached 98% on the reading plate number. And also OCR method are 88% with stable image reading and good lighting conditions as well as the standard font type of a book. Meanwhile, best method and technique to detect human skin is by using Skin Color Segmentation: CIELab color space with accuracy of 96.87%. While the algorithm for classification using Convolutional Neural Network (CNN), the accuracy rate of 98%&#x0D; Key word: Computer Vision, Segmentation, Object Recognition, Text Recognition, Skin Color Detection, Motion Detection, Disability Application

EFFICACY OF CIELAB AND CMYK COLOR SPACES IN LEUKEMIA IMAGE ANALYSIS: A COMPARISON BY STATISTICAL TECHNIQUES

There are several color models available and which color model to be used is a question to many researchers in the field of Medical Image Processing and Analysis. In this paper, the suitability of using the CIELAB and CMYK color spaces in processing and analyzing blood smear images of leukemia is assessed for comparison. Leukemia is commonly known as blood cancer and it usually leads to an abnormal proliferation of leukocytes (White Blood Cells) in the bone marrow and blood. The diagnosis of leukemia is primarily done by Pathologists by microscopically examining the blood and bone marrow smears of the suspected patient. Image processing-based methods can be used for automated detection and classification of leukemia to assist the Pathologists for a speedy diagnosis. The proposed study used [Formula: see text]-means clustering to segment the leukocytes and leukemic blast cells. The microscopic smear images in RGB color format were transformed and processed in CIELAB as well as CMYK color spaces for comparison. Statistical analysis was performed using Student’s [Formula: see text] test. The visual observation of the segmented images revealed that, processing the images in the CIELAB color space is comparatively better than the CMYK color space and it is reflected in the results of statistical comparison by Student’s [Formula: see text] test. The study assessed the suitability of using the CIELAB and CMYK color spaces in segmentation and analysis of microscopic smear images of Leukemic and Normal cases and found that processing the images in CIELAB color space is comparatively better than CMYK and such comparative analysis is not available in the literature.

Bison muscle discrimination and color stability prediction using near-infrared hyperspectral imaging

A novel photonics-based multivariate pattern recognition technique is presented to segregate bison meat samples based on muscle type, ageing, and retail display period. The technique uses color attributes obtained from visible to near-infrared hyperspectral images (400–1000 nm) to predict the stability of bison muscle samples. Unsupervised and supervised classification methods were implemented with an aim to discriminate muscle samples based on muscle type, ageing period, and retail display period. The wavelength region from 500 to 690 nm which is associated with the a ∗ value in the CIE Lab color space was found to be significantly important for the classification of muscle samples over the storage period. Partial least squares discriminant analysis (PLS-DA) demonstrated classification accuracies from 0.88 to 0.94 for the classification of muscle type, ageing period and retail display followed by development of classification maps. For the estimation of color changes in the muscle samples over the storage and retail display period, a ∗ value was predicted with an R 2 of calibration of 0.89, and R 2 of cross-validation of 0.88. Conclusively, the wavelength range from 550 to 690 nm can significantly contribute to sorting and predicting freshness of bison muscle samples based on muscle type, color stability and storage period. • Muscles were classified (>0.90 accuracy) at 2 d post-mortem using a classification map. • Classification accuracies were moderate (<0.90 accuracy) for samples based on ageing period. • Prediction of color values ( a ∗ value) was successful using selected wavelength range. • Hyperspectral imaging provided reliable segregation of muscles by color stability.

The Effect of High-Pressure Treatment and Skimming on Caprine Milk Proteins

Background: Proteins are susceptible to HP-treatment and there is a need to determine the applicability of HP-treatment in dairy production. The aim of this study was to determine the effect of HP-treatment at 200–500 MPa (tconst. = 10 min; Tconst. = 20 °C) and skimming of HP-treated milk on the content of nitrogen compounds and protein composition of caprine milk. Methods: The content of nitrogen (total, non-casein, non-protein) was determined using the Kjeldahl method. Casein fractions and whey proteins were separated using SDS-PAGE electrophoresis. Color parameters were measured in the CIELAB color space. Results: HP-treatment decreased (p &lt; 0.05) the content of non-casein nitrogen and soluble whey proteins. Skimming decreased the content of nitrogen compounds, and the noted decrease was more pronounced in HP-treated milk. Pressure and skimming had no influence on the proportions of α-, β-, κ-casein, β-lactoglobulin and α-lactalbumin. Total color difference (ΔE) increased with a rise in pressure, particularly in skim milk. Conclusion: HP-treatment led to a loss of protein solubility at pH 4.6 in caprine milk. In HP-treated milk, skimming did not induce changes in protein composition, despite a decrease in the content of nitrogen compounds after the separation of the cream layer. Higher values of ΔE in skim milk than in whole milk point to changes in colloidal phase components.

Prediction of Ratoon Sugarcane Family Yield and Selection Using Remote Imagery

Remote sensing techniques and the use of Unmanned Aerial Systems (UAS) have simplified the estimation of yield and plant health in many crops. Family selection in sugarcane breeding programs relies on weighed plots at harvest, which is a labor-intensive process. In this study, we utilized UAS-based remote sensing imagery of plant-cane and first ratoon crops to estimate family yields for a second ratoon crop. Multiple families from the commercial breeding program were planted in a randomized complete block design by family. Standard red, green, and blue imagery was acquired with a commercially available UAS equipped with a Red–Green–Blue (RGB) camera. Color indices using the CIELab color space model were estimated from the imagery for each plot. The cane was mechanically harvested with a sugarcane combine harvester and plot weights were obtained (kg) with a field wagon equipped with load cells. Stepwise regression, correlations, and variance inflation factors were used to identify the best multiple linear regression model to estimate the second ratoon cane yield (kg). A multiple regression model, which included family, and five different color indices produced a significant R2 of 0.88. This indicates that it is possible to make family selection predictions of cane weight without collecting plot weights. The adoption of this technology has the potential to decrease labor requirements and increase breeding efficiency.

Automated detection of Covid-19 disease using deep fused features from chest radiography images

The health systems of many countries are desperate in the face of Covid-19, which has become a pandemic worldwide and caused the death of hundreds of thousands of people. In order to keep Covid-19, which has a very high propagation rate, under control, it is necessary to develop faster, low-cost and highly accurate methods, rather than a costly Polymerase Chain Reaction test that can yield results in a few hours. In this study, a deep learning-based approach that can detect Covid-19 quickly and with high accuracy on X-ray images, which are common in every hospital and can be obtained at low cost, was proposed. Deep features were extracted from X-Ray images in RGB, CIE Lab and RGB CIE color spaces using DenseNet121 and EfficientNet B0 pre-trained deep learning architectures and then obtained features were fed into a two-stage classifier approach. Each of the classifiers in the proposed approach performed binary classification. In the first stage, healthy and infected samples were separated, and in the second stage, infected samples were detected as Covid-19 or pneumonia. In the experiments, Bi-LSTM network and well-known ensemble approaches such as Gradient Boosting, Random Forest and Extreme Gradient Boosting were used as the classifier model and it was seen that the Bi-LSTM network had a superior performance than other classifiers with 92.489% accuracy.

Effects of shade and thickness on the translucency parameter of anatomic-contour zirconia, transmitted light intensity, and degree of conversion of the resin cement

Statement of problemAnatomic-contour zirconia prostheses are usually cemented with resin cement. However, information regarding the effects of the zirconia shade and thicknesses on the translucency of the prosthesis, the intensity of the transmitted light beneath the prosthesis, and the subsequent degree of conversion in the resin cement is sparse. PurposeThe purpose of this in vitro study was to investigate the translucency parameter in 3 anatomic-contour zirconia specimens of 2 shades at 5 different thicknesses and to investigate the transmitted light intensity and degree of conversion of the resin cement beneath the ceramic specimens by using a traditional zirconia and a lithium disilicate glass-ceramic as controls. Material and methodsCeramic specimens from 1 anatomic-contour zirconia in a generic shade (CAP FZ) and 2 anatomic-contour zirconias in A2 shade (Zirlux and Luxisse) were used. Lithium disilicate in HT A2 shade (IPS e.max CAD) and traditional zirconia in a generic shade (CAP QZ) were used as controls. A total of 125 ceramic specimens (n=25) were fabricated to a final specimen dimension of 12×12 mm and in thicknesses of 1.0, 1.25, 1.5, 1.75, and 2.0 mm according to the manufacturers’ recommendations. The CIELab color space for all specimens placed against a white and black background was measured with a spectrophotometer (CM-2600D), and the translucency parameters were calculated for the materials at various thicknesses. A light-polymerizing unit (DEMI LED) was used to polymerize the resin cement (Variolink II) placed beneath the ceramic specimens. Transmitted light intensity from the polymerization unit beneath the ceramic specimens was measured by using a spectrophotometer (MARC Resin Calibrator), and the transmittance of each specimen was calculated. The coefficient of absorption of each material was calculated from the regression analysis between the natural log of transmittance and specimen thickness. The degree of conversion of resin cement was measured by using a Fourier transformation infrared (FTIR) spectrophotometer. The results were analyzed by using 2-way ANOVA (α=.05). The relationship between the transmittance and the translucency parameter was evaluated by plotting the transmittance against the translucency parameter value of each specimen. ResultsThe translucency parameter decreased with increasing thickness in all 5 material groups. All anatomic-contour zirconia had lower translucency parameters than e.max CAD (P<.001). The same results were found for the intensity of the transmitted light (P<.001). Both A2 shade anatomic-contour zirconia (Zirlux and Luxisse) showed significantly lower light transmittance than a generic shade anatomic-contour zirconia (CAP FZ) (P<.001). The coefficients of absorption were found to range from 0.63 to 1.72 mm-1, and reflectance from 0.10 to 0.25. The results from the degree of conversion of resin cement after polymerization through 1 to 2 mm of specimens showed a significantly higher degree of conversion in the e.max group than in all other groups (P<.001). The correlation between translucency parameter and the intensity of the transmitted light suggested that the relationship was shade dependent. ConclusionsThe translucency parameter and the transmitted light intensity of ceramic material were influenced by the type of ceramic and the shade and thickness of the ceramic. The combined effects of layer thickness and the intensity of the transmitted light in the A2 shade anatomic-contour zirconia (Zirlux and Luxisse) resulted in a lower degree of conversion in resin cement than in a generic shade anatomic-contour zirconia (CAP FZ) at layer thicknesses of 1.75 and 2 mm.

Chroma Enhancement in CIELAB Color Space Using a Lookup Table

In this study, we present a method of chroma enhancement in the CIELAB color space and compare it with that in the RGB color space. Color image enhancement using the CIELAB color space has the disadvantage that the color gamut problem occurs because the conversion to the RGB color space is necessary to display the image. However, since the CIELAB color space is based on human visual perception, the quality of the resulting images is expected to be higher than that of the RGB color space. In the method using the CIELAB color space, we introduce a lookup table to reduce the calculation costs. Experiments comparing image enhancement results obtained from two color spaces are performed using several digital images.

Naturalness and aesthetics of colors – Preference for color compositions perceived as natural

What makes a colored image, e.g. an abstract painting or a landscape, look pleasing? We hypothesized that a preference for complex color compositions, such as paintings and images of natural scenes, might be related to how natural the colors are perceived. We tested this possibility with two experiments in which the degree of naturalness of images was manipulated by rotating their color gamut rigidly in the color space CIELAB. This changed just the hue composition, but preserved saturation and lightness. In the first experiment we obtained individual scaling curves for perceived naturalness and for preference as a function of the angle of gamut rotation for a small set of images. The naturalness and preference scaling curves were found to be largely similar and their maxima were close to the original image. In the second experiment, we tested whether this effect generalized to a larger set of images. We used a simultaneous 5AFC procedure where in each trial participants had to select the most natural or the most preferred image from five different rotations of the color gamut. The results confirmed the first experiment and showed that, in general, the images perceived as the more natural tend to be the ones that are preferred. Together these results show that perceived naturalness and preference are indeed perceptually closely related and may be driven by related mechanisms.

Body coloration as a dynamic signal during intrasexual communication in a cichlid fish

BackgroundIntrasexual competition over access to resources can lead to aggression between individuals. Because overt aggression, i.e. fights, can be costly for contestants, the communication of aggressive motivation prior to engagement in a physical fight is often mediated by conventional signals. Animals of various taxa, including fishes, display visual signals such as body coloration that can dynamically be adjusted depending on the individual’s motivation. Male individuals of the West African cichlid Pelvicachromis taeniatus express a yellow body coloration displayed during courtship but also in an intrasexual competition context.ResultsWithin-individual variation in male yellow body coloration, as quantified with standardized digital photography and representation in a CIELab color space, was examined in a mating context by exposing males to a female and in a competitive intrasexual context, i.e. in a dyadic contest. Additionally, spectrometric reflectance measurements were taken to obtain color representations in a physiological color space based on spectral sensitivities of our model species. Exposure to females did not significantly affect male color expression. However, analysis of body coloration revealed a change in within-individual color intensity and colored area after interaction with a male competitor. In dominant males, extension of coloration was positively correlated with restrained aggression, i.e. displays, which in turn explained dominance established between the two contestants.ConclusionBody coloration in male P. taeniatus is a dynamic signal that is used in concert with display behavior in communication during intrasexual competition.

Relationship between color and physico-chemical properties of cashew apple (Anacardium occidentale L.) at different days of storage

Cashew is a fruiting specimen exported from different countries, including Venezuela, due to its high nutritional value and unique taste. However, only the fruit (cashew nut) is considered the most used part for consumption while the pseudo-fruit (cashew apple) is discarded due to its strong taste and smell. This study is based on the changes that occur in the physical and chemical composition of the pseudo-fruit of cashew (Anacardium occidentale L.) in different days of storage (0, 3, 6, 9, 12) related to the color analysis of the pseudo-fruit. Image analysis was performed using the CIELab color space, which revealed different maturity stages for samples from day 0 to day 12. Nevertheless, antioxidant activity refers to ascorbic acid, and polyphenols content showed a degradation before day 6 of storage. These results prove that cashew apples can be stored for long-term at room temperature (25 °C), but the color and physico-chemical properties suffer some changes decreasing their nutritional value after day 6 of storage. A correlation between image analysis and chemical parameters can be used to evaluate the optimal maturity stage in samples.