Color Pairs Research Articles

Facial UV photo imaging for skin pigmentation assessment using conditional generative adversarial networks

Skin pigmentation is associated with skin damages and skin cancers, and ultraviolet (UV) photography is used as a minimally invasive mean for the assessment of pigmentation. Since UV photography equipment is not usually available in general practice, technologies emphasizing pigmentation in color photo images are desired for daily care. We propose a new method using conditional generative adversarial networks, named UV-photo Net, to generate synthetic UV images from color photo images. Evaluations using color and UV photo image pairs taken by a UV photography system demonstrated that pigment spots were well reproduced in synthetic UV images by UV-photo Net, and some of the reproduced pigment spots were difficult to be recognized in color photo images. In the pigment spot detection analysis, the rate of pigment spot areas in cheek regions for synthetic UV images was highly correlated with the rate for UV photo images (Pearson’s correlation coefficient 0.92). We also demonstrated that UV-photo Net was effective for floating up pigment spots for photo images taken by a smartphone camera. UV-photo Net enables an easy assessment of pigmentation from color photo images and will promote self-care of skin damages and early signs of skin cancers for preventive medicine.

A Hierarchical Superpixel-Based Approach for DIBR View Synthesis.

View synthesis allows observers to explore static scenes using aligned color images and depth maps captured in a preset camera path. Among the options, depth-image-based rendering (DIBR) approaches have been effective and efficient since only one pair of color and depth map is required, saving storage and bandwidth. The present work proposes a novel DIBR pipeline for view synthesis that properly tackles the different artifacts that arise from 3D warping, such as cracks, disocclusions, ghosts, and out-of-field areas. A key aspect of our contributions relies on the adaptation and usage of a hierarchical image superpixel algorithm that helps to maintain structural characteristics of the scene during image reconstruction. We compare our approach with state-of-the-art methods and show that it attains the best average results in two common assessment metrics under public still-image and video-sequence datasets. Visual results are also provided, illustrating the potential of our technique in real-world applications.

The impact of transition type on chromatic adaptation under dual lighting conditions

Over the years, many CATs (chromatic adaptation transform), typically based on the von Kries coefficient rule, have been developed to predict the corresponding colors under different illuminants. However, these CATs were derived for uniform stimuli surrounded by a uniform adapting field. To investigate the adaptation state under spatially complex illumination, an achromatic matching experiment was conducted under dual lighting conditions with three color pairs and two transition types. It has been found that the transition type has an impact on both the equivalent chromaticity and degree of adaptation. These results can help build a comprehensive von Kries based CAT model, with considering the spatial complexity of illumination.

Analysis of Hue Circle Perception of Congenital Red-green Congenital Color Deficiencies Based on Color Vision Model

To investigate individual property of internal color representation of congenital red-green color-deficient observers (CDOs) and color-normal observers (CNOs) precisely, difference scaling experiment using pairs of primary colors was carried out for protans, deutans, and normal trichromats, and the results were analyzed using multi-dimensional Scaling (MDS). MDS configuration of CNOs showed circular shape similar to hue circle, whereas that of CNO showed large individual differences from circular to U- shape. Distortion index, DI, is proposed to express the shape variation of MDS configuration. All color chips were plotted in the color vision space, (L, r/g, y/b), and the MDS using a non-linear conversion from the distance in the color vision space to perceptual difference scaling was successful to obtain U-shape configuration that reflects internal color representation of CDOs.

Using Neurostimulation to Augment the Encoding of Information in Visual Working Memory

Storage limits in visual working memory (VWM) impose an information-processing bottleneck, restricting input to broader cognition. Our capacity to store random, uncorrelated input is extremely limited (e.g., ~3 colors), but previous work has shown that more content can be stored if there are statistical regularities in the input (e.g., if pairs of colors tend to co-occur; Brady, Konkle, and Alvarez, 2009). Here, we used a novel non-invasive brain stimulation technique, trans-cranial random noise stimulation (tRNS), to enhance the learning of these regularities and consequently increase the amount of information retained in VWM. We presented three separate groups of participants with displays consisting of 8 colored circles, arranged in 4 concentric pairs. The colors disappeared, after which participants reported the identity of a cued circle by choosing from the 8 possible color-options. Participants in the “tRNS+Pattern” group received 20-minutes of neurostimulation to the right posterior parietal and right dorsolateral prefrontal cortices during the first 20-minutes of testing, and were also presented with displays containing regularities (i.e. 4 pairs of colors appeared together 80% of the time). Though the remaining groups of participants were connected to the neurostimulator, they did not receive stimulation. For these sham stimulation conditions, members of the “no tRNS-Pattern” group were also presented with displays with the same regularities, whereas color combinations for the “no tRNS-Uniform” group were sampled from a uniform distribution. Replicating the effects observed by Brady et al. (2009), “no tRNS-Pattern” participants were able to store more items in memory, relative to their “no tRNS-Uniform” counterparts. Critically, neuroenhancement effects were observed, such that members of the “tRNS+Pattern” group demonstrated the most superior performance. Performance across all groups plummeted to comparable levels when regularities were removed, reaffirming that the observed benefits reflect enhanced encoding. Neurostimulation may prove instrumental towards augmenting VWM and broader cognition.

Color and cross diagonal symmetric pair co-occurrence matrix

Objectives: The main goal of this study is to derive an efficient feature vector to capture both the color and texture information. This makes the proposed descriptor as a multipurpose descriptor. Methodology: This study derived color information by combining the individual histograms of H, S and V plane. A texture descriptor is derived by considering the relationship: i) between pairs of symmetric cross pixels and ii) between pairs of symmetric diagonal pixels of the 3 x 3 neighborhood. The relationship is derived using XOR and AND logical functions. Findings: This study derived a unique six bit code and constructed a co-occurrence matrix. The GLCM features are derived on this. To reduce the complexity, this study also derived another descriptor by indexing the six bit code using the rotational invariant property. Novelty: The proposed color and texture descriptors give better results, and a significant improvement is achieved in this study by concatenating these two descriptors for CBIR. Keywords: CBIR; firstorder; symmetric; derivatives; histogram; indexed; GLCM

The giant freshwater prawnMacrobrachium rosenbergiialters background colour preference after metamorphosis from larvae to postlarvae: In association with nature of phototaxis

The giant freshwater prawn Macrobrachium rosenbergii larvae have apposition eyes and are positively phototactic, whereas the postlarvae (PL) have superposition eyes and are negatively phototactic. M. rosenbergii has colour vision as early as larval stage. We discovered that M. rosenbergii alters background colour preference after metamorphosis from larvae to PL in association with nature of phototaxis. The test circular glass aquaria covered with a pair of two-colour papers contained with a group of 100 larvae or 20 Pl, and the number of individuals in each colour background was recorded five times for each colour pair. The background colours tested were light blue, green, yellow, red, white and black. The numbers of larvae or PL in each colour background of different pairs were analysed by the Thurstone's law of comparative judgment. In the larvae, significant bias towards yellow was evident. In the PL, of the four pairings of black with other colours, all biased to black. The mean z-scores were highest for yellow in the larvae, and for black in the PL. To determine the possible background brightness preference of the larvae and PL, six different colour backgrounds were presented in pairs. The larvae significantly preferred light blue over dark blue, white over yellow and white over black. The PL exhibited reversed preference. The relationship between z-scores and light reflectance levels of five colour papers was significantly positive in the larvae and negative in the PL. The observed background colour preference was probably due to relative brightness rather than chromaticity difference.

SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). IV. Spatial Clustering and Halo Masses of Submillimeter Galaxies

Abstract We analyze an extremely deep 450 μm image (1σ = 0.56 mJy beam−1) of a ≃300 arcmin2 area in the CANDELS/COSMOS field as part of the Sub-millimeter Common User Bolometric Array-2 Ultra Deep Imaging EAO Survey. We select a robust (signal-to-noise ratio ≥4) and flux-limited (≥4 mJy) sample of 164 submillimeter galaxies (SMGs) at 450 μm that have K-band counterparts in the COSMOS2015 catalog identified from radio or mid-infrared imaging. Utilizing this SMG sample and the 4705 K-band-selected non-SMGs that reside within the noise level ≤1 mJy beam−1 region of the 450 μm image as a training set, we develop a machine-learning classifier using K-band magnitude and color–color pairs based on the 13-band photometry available in this field. We apply the trained machine-learning classifier to the wider COSMOS field (1.6 deg2) using the same COSMOS2015 catalog and identify a sample of 6182 SMG candidates with similar colors. The number density, radio and/or mid-infrared detection rates, redshift and stellar-mass distributions, and the stacked 450 μm fluxes of these SMG candidates, from the S2COSMOS observations of the wide field, agree with the measurements made in the much smaller CANDELS field, supporting the effectiveness of the classifier. Using this SMG candidate sample, we measure the two-point autocorrelation functions from z = 3 down to z = 0.5. We find that the SMG candidates reside in halos with masses of ≃(2.0 ± 0.5) × 1013 h −1 M ☉ across this redshift range. We do not find evidence of downsizing that has been suggested by other recent observational studies.

Screening properties of quark-gluon plasma obtained from distribution and correlation functions of the constituent quasiparticle model

Based on the constituent quasiparticle model of quark-gluon plasma (QGP), the matrix elements of the density operator and the Wigner function in the color phase space are presented in form of color path integrals over Wiener and SU(3) group Haar measures. Monte Carlo calculations of quark and gluon momentum distributions and spatial pair distribution functions have been carried out for the strongly coupled QGP plasma in thermal equilibrium at zero baryon chemical potential. The Debye screening mass and the running coupling constant have been obtained from the spatial pair distribution function and are in agreement with the available lattice QCD data. At densities related to the average interparticle distance more than 0.4 fm the gluon bound states in the form of glueballs have been found. Comparison with the Maxwell Boltzmann distribution shows significant influence of interparticle interaction on high energy asymptotics of the momentum distribution functions, resulting in appearance of quantum tails. The new color pair correlation function has been introduced, and related new color screening mass has been discussed.

Using watermark visibility measurements to select an optimized pair of spot colors for use in a binary watermark

Red does not stand out brightly to dichromatic individuals with a different sense of color from the majority. However, they know that the color of passion is red. In this paper, we investigate the red appearance and color sensitivity of people with different types of color blindness: “Protan and Deutan.”

Individual differences in feelings about red

Observers with a colour vision deficiency usually find it more difficult to discriminate between red and green colours, due to genetic variation in cone spectral sensitivity. Daltonization methods aim to enhance colour stimuli in order to increase the visual difference between them for such observers. In this work we focus on filtering the stimulus in the reflectance domain prior to conversion to colorimetry. This is hypothesized to enable a more precise tuning of the enhancement to the spectral absorptions of the observer with a colour vision deficiency. A spectral sharpening filter was developed and applied to spectral reflectances for a range of colour pairs which observers with a colour vision deficiency would be expected to find difficult to discriminate. The reflectance pairs were converted to colorimetry and presented on a colour display, where the visual difference between the pairs was evaluated by observers in a psychophysical experiment. Results suggest that a suitable filter can lead to an increase in the difference between the red-green pairs.

A cross-modal adaptive gated fusion generative adversarial network for RGB-D salient object detection

Salient object detection in RGB-D images aims to identify the most attractive objects in a pair of color and depth images for the observer. As an important branch of salient object detection, it focuses on solving the following two major challenges: how to achieve cross-modal fusion that is efficient and beneficial for salient object detection; how to effectively extract the information of depth image with relatively poor quality. This paper proposes a cross-modal adaptive gated fusion generative adversarial network for RGB-D salient object detection by using color and depth images. Specifically, the generator network adopts double-stream encoder-decoder network and receives RGB and depth images at the same time. The proposed depthwise separable residual convolution module is used to deal with deep semantic information, and the processed feature is combined with side-output features of the encoder network progressively. In order to compensate for the shortcoming of poor quality of the depth image, the proposed method adds the cross-modal guidance from the side-output features of the RGB stream to the decoder network of depth stream. The discriminator network adaptively fuses the features of double streams using a gated fusion module, then sends the gated fusion saliency map to the discriminator to distinguish the similarity from ground-truth map. Adversarial learning forms the better generator network and discriminator network, and the gated fusion saliency map generated by the best generator network is served as final result. Experiments on five publicly RGB-D datasets demonstrate the effect of cross-modal fusion, depthwise separable residual convolution and adaptive gated fusion. Compared with the state-of-the-art methods, our method achieves the better performance.

The optimal number of sensors for a digital imaging system from the perspective of metamer mismatching

AbstractMetamer mismatching occurs in both the human visual system and digital imaging systems. Increasing the number of sensors in digital imaging systems is an efficient method to reduce the degree of metamer mismatching. This study investigates the number of sensors that are needed for the digital imaging systems to have a similar ability to the human sensor system in distinguishing colors from the perspective of metamer mismatching. Optimal spectral reflectance was generated, and a dataset with more than 47 million previously collected practical spectral reflectance functions was used to derive the metameric color pairs. Different sets of Gaussian‐shaped functions were designed to model the spectral sensitivity functions of the digital imaging systems. Both the metamer mismatching volumes and color differences were used to characterize the degree of metamer mismatching for pairs of samples, which were metameric to the imaging systems but appeared different to the human sensor system. The results show that the practical metamer mismatching volumes are substantially smaller than the theoretical ones. The results also show that both the metamer mismatching volumes and color differences are significantly reduced by increasing the number of sensors from three to five for the digital imaging system but are only slightly reduced by further increasing the number of sensors from five to seven. This indicates that five sensors is an efficient and optimal solution for an imaging system with Gaussian‐shaped sensors to have a similar ability in distinguishing colors compared to the human sensor system.

Colorimetric Observer Categories for Young and Aged Using Paired-Comparison Experiments

Observers with normal color vision have different color perceptions since their retinal cones have different spectral responses, especially when the color pairs are constituted by different primary colors. In order to categorize the color-matching functions (CMFs) for young and aged observers, seven devices with different primary colors were performed on the clustering of observers’ CMFs. Four CMFs were generated from Beijing Institute of Graphic Communication (BIGC) with paired-comparison color matching experiments based on five printed colors from young and aged observers performed under fluorescent light source (Experiment I). Besides, color comparison experiments based on three printed colors under light emitting diodes (LEDs) light source were also carried out (Experiment II). And then, the existing CMFs, including Commission Internationale de l’ Eclairage 1964 (CIE 1964), CIE 1989 standard deviate observer (CIE 1989 SDO), CIE 2006, Sarkar 1 to Sarkar 8, Asano 1 to Asano 10, BIGC 1 to BIGC 4 were tested with the results from Experiments I and II respectively. The results indicated that the visual data from young and aged observers had quite large discrepancies. When they viewed printed materials illuminated by fluorescent and LED light sources in a field of view larger than 10°, based on the standardized residual sum of squares (STRESS) values and the number of the observers contributed to the minimum STRESS values, two new CMFs were proposed to represent the young and aged observers who participated in our experiments.

Supramolecular optimization of the visual contrast for colorimetric indicator assays that release resorufin dye.

A tetralactam macrocycle acts as a novel supramolecular adjuvant to capture a released resorufin dye and create a higher contrasting yellow/blue color change for enhanced naked eye interpretation of a colorimetric indicator assay.

Visual signal evolution along complementary color axes in four bird lineages.

ABSTRACTAvian color patterns function in varied behavioral contexts, most being produced by only a handful of mechanisms including feather nanostructures and pigments. Within a clade, colors may not occupy the entire available space, and incorporating complementary colors may increase the contrast and efficacy of visual signals. Here, we describe plumage patterns in four ecologically and phylogenetically diverse bird families to test whether they possess complementary colors. We present evidence that plumage colors in each clade cluster along a line in tetrachromatic color space. Additionally, we present evidence that in three of these clades, this line contains colors on opposite sides of a line passing through the achromatic point (putatively complementary colors, presenting higher chromatic contrast). Finally, interspecific color variation over at least some regions of the body is not constrained by phylogenetic relatedness. By describing plumage patterns in four diverse lineages, we add to the growing body of literature suggesting that the diversity of bird visual signals is constrained. Further, we tentatively hypothesize that in at least some clades possessing bright colors, species-specific plumage patterns may evolve by swapping the distributions of a complementary color pair. Further research on other bird clades may help confirm whether these patterns are general across bird families.

The Color Influence on the Audience of Interactive Television

Науковий рецензований журнал відкритого доступу, що публікує статті з актуальних питань загальнотеоретичних, мистецьких, історичних, практичних аспектів у галузі аудіовізуального мистецтва та виробництва.

Quantum Representation of Indexed Images and its Applications

Indexed images have been widely used in classical digital image processing, however there have been no reports on the representation and applications of indexed images in quantum image processing so far. To solve the representation problem of indexed images on a quantum computer, a quantum indexed image representation (QIIR) method is proposed in the paper. A quantum indexed image consists of a quantum data matrix and a quantum palette matrix. Each data structure is based on the basic states of qubit sequence to represent information, including pixel positions and pixel values in the data matrix, and indexes and color values in the palette matrix. Several simple geometric and color transformations of quantum indexed images are presented later, including orthogonal rotation, cyclic shift, color inversion, color replacement and color look-up. Finally, a quantum indexed image steganography based on EzStego is proposed. In this scheme, the distance between two arbitrary color values in the quantum palette is first calculated, and then several effective color pairs are obtained. At last, according to embedded message bits, pixel values in the data matrix are updated in light of effective color pairs, and a new quantum data matrix with embedded message is obtained. The proposed scheme can be executed on a future quantum computer. The feasibility and validness of this scheme are verified on a classical computer from four aspects: visual quality, embedding capacity, robustness and security.

A Color‐Pair Based Approach for Accurate Color Harmony Estimation

AbstractHarmonious color combinations can stimulate positive user emotional responses. However, a widely open research question is: how can we establish a robust and accurate color harmony measure for the public and professional designers to identify the harmony level of a color theme or color set. Building upon the key discovery that color pairs play an important role in harmony estimation, in this paper we present a novel color‐pair based estimation model to accurately measure the color harmony. It first takes a two‐layer maximum likelihood estimation (MLE) based method to compute an initial prediction of color harmony by statistically modeling the pair‐wise color preferences from existing datasets. Then, the initial scores are refined through a back‐propagation neural network (BPNN) with a variety of color features extracted in different color spaces, so that an accurate harmony estimation can be obtained at the end. Our extensive experiments, including performance comparisons of harmony estimation applications, show the advantages of our method in comparison with the state of the art methods.

Complete colourings of hypergraphs

A complete c-colouring of a graph is a proper colouring in which every pair of distinct colours from [c]={1,2,…,c} appears as the colours of endvertices of some edge. We consider the following generalisation of this concept to uniform hypergraphs. A complete c-colouring for a k-uniform hypergraph H is a mapping from the vertex set of H to [c], such that (i) the colour set used on each edge has exactly k elements, and (ii) every k-element subset of [c] appears as the colour set of some edge. In this paper we exhibit some differences between complete colourings of graphs and hypergraphs. First, it is known that every graph has a complete c-colouring for some c.In contrast, we show an infinite family of hypergraphs H that do not admit a complete c-colouring for any c. We also extend this construction to λ-complete colourings (for 0<λ≤1), where condition (ii) is substituted with: at least λck different colour sets appear on edges.We establish upper and lower bounds on a maximum degree, which guarantees the existence of a complete colouring of any hypergraph. Moreover, we prove that it is NP-complete to determine if a given hypergraph has a λ-complete colouring. Next, we show that, unlike graphs, hypergraphs do not have the so-called interpolation property, i.e., we construct hypergraphs that have a complete r-colouring and a complete s-colouring, but no complete t-colouring for some t such that r<t<s.Finally, we investigate the notion of λ-complete colourings of graphs (i.e., 2-uniform hypergraphs). We show that λ-complete colourings have the same interpolation property as complete colourings. Moreover, we prove that it is NP-complete to decide whether a tree with c2 edges has a λ-complete c-colouring, which strengthens the result by Cairnie and Edwards (1997).