Online Color Research Articles

Coloring Triangle-Free Rectangle Overlap Graphs with $$O(\log \log n)$$ O ( log log n ) Colors

Recently, it was proved that triangle-free intersection graphs of $n$ line segments in the plane can have chromatic number as large as $\Theta(\log\log n)$. Essentially the same construction produces $\Theta(\log\log n)$-chromatic triangle-free intersection graphs of a variety of other geometric shapes---those belonging to any class of compact arc-connected sets in $\mathbb{R}^2$ closed under horizontal scaling, vertical scaling, and translation, except for axis-parallel rectangles. We show that this construction is asymptotically optimal for intersection graphs of boundaries of axis-parallel rectangles, which can be alternatively described as overlap graphs of axis-parallel rectangles. That is, we prove that triangle-free rectangle overlap graphs have chromatic number $O(\log\log n)$, improving on the previous bound of $O(\log n)$. To this end, we exploit a relationship between off-line coloring of rectangle overlap graphs and on-line coloring of interval overlap graphs. Our coloring method decomposes the graph into a bounded number of subgraphs with a tree-like structure that "encodes" strategies of the adversary in the on-line coloring problem. Then, these subgraphs are colored with $O(\log\log n)$ colors using a combination of techniques from on-line algorithms (first-fit) and data structure design (heavy-light decomposition).

AUTOMATIC SCALING OF WEB APPLICATIONS FOR CLOUD COMPUTING SERVICES: A REVIEW

Now days there are many web applications can get benefit from automatic scaling property of cloud where the no of resources usage can be scale up and down automatically by cloud service provider. So here present system that provides automatic scaling for web application in cloud environment. So every application instance encapsulated inside virtual machine and model it as the Class Constraint Bin Packing (CCBP) problem. Where each class represents an application and each server is a bin and uses virtualization technology for fault isolation. Now many business customers need good satisfy response services from cloud. So design and develop semi online color set algorithm that achieve good demand satisfaction ratio and as well as when load becomes low it reducing number of server and save energy. Experiment results compare open source implementation of Amazon EC2 demonstrates that system can improve the throughput by 180% over. And system can restore the normal quality of service five times as fast when huge crowd happens. Take supports of green computing to adjusting the placement of application instance adaptively and putting ideal machine into the standby mode.

Generalized dynamic storage allocation

Graph Theory Dynamic Storage Allocation is a problem concerned with storing items that each have weight and time restrictions. Approximate algorithms have been constructed through online coloring of interval graphs. We present a generalization that uses online coloring of tolerance graphs. We utilize online-with-representation algorithms on tolerance graphs, which are online algorithms in which the corresponding tolerance representation of a vertex is also presented. We find linear bounds for the online-with-representation chromatic number of various classes of tolerance graphs and apply these results to a generalization of Dynamic Storage Allocation, giving us a polynomial time approximation algorithm with linear performance ratio.

Scanning Measurement of Coated Glass Color-Difference and Design of Anti-Interference

Based on the colorimetric theory and combined with the production process of glass industry, a color-difference measurement system was designed. The system was applied to online color-difference detection for coated glass. Scanning measurement of color-difference based on spectroscopy was detailed, and the technologies of light source modulation and signal demodulation synchronization were introduced into the system. This avoided using sensor masks or soft curtain to eliminate backlight interference. Under the light source with fluctuations and other background noise, the new system can get robust measurement values. The experimental results show that the anti-interference method smooths the curve of color-difference, and improves the signal-to-noise ratio. The system meets the demands of practical color-difference testing, and provides a new method for online color measurement with high accuracy.

Real time hand detection in a complex background

Hand gesture recognition has gained the interest of many researchers in recent years, as it has become one of the most popular Human Computer Interfaces. The first step in most vision-based gesture recognition systems is the hand region detection and segmentation. This segmentation can be a particularly challenging task when it comes to complex backgrounds and varying illumination. In such environments, most hand detection techniques fail to obtain the exact region of the hand shape, especially in cases of dynamic gestures. Meeting these requirements becomes even more difficult, due to real-time operation demand. To overcome these problems, in this paper, we propose a new method for real-time hand detection in a complex background. We employ a combination of existing techniques, based on motion detection and introduce a novel skin color classifier to improve segmentation accuracy. Motion detection is based on image differencing and background subtraction. Skin color detection is accomplished via a color classification technique that employs online color training, so that the system can dynamically adapt to the variety of lighting conditions and the user׳s skin color as well as possible. Morphological features of the detected hand in previous frames are employed to estimate the probability of a pixel belonging to the hand section in the current frame. Finally, the derived motion, color and morphological information are combined to detect the hand region. Experimental results show significant improvement in hand region detection, compared to existing methods with an average accuracy of 98.75%.

在线式分光测色仪发展现状

The principle of color measurement is introduced,and the characteristics requirements and technical difficulties of on-line color measurement are summarized. The development process and the current state of the art of on-line color measurement technology are also presented. The specifications,applications and system structures of several advanced on-line spectrophotometes abroad are presented in detail. The characteristics and advantages of every instrument are highlighted. The development trend of on-line spectrophotometer is discussed from two aspects of technical perspective and application requirements in this paper,which will provide a reference for study on the development of on-line spectrophotometer.

Instrumental colour measurement as a tool for light veal carcasses online evaluation

Abstract. Eight-hundred and forty-five veal carcasses (535 males and 310 females) from Pirenaica breed and its crosses with Charolais and Limousin were used to compare carcass colour visual assessments 60 min post-mortem with the values obtained using a spectrocolorimeter (CIE Lab colour system) on the pectoralis superficialis muscle. Carcass weights ranged between 240 and 360 kg. Visual colour was subjectively evaluated by two trained assessors. The best correlation between visual appraisal and L* was observed in carcasses of 300–320 kg. A relatively strong correlation between visual appraisal and a* values was observed in carcasses of 280–300 kg of weight. However, the correlation between b* and visual appraisal was low. Using discriminant functions that included L* and a*, the spectrocolorimeter classified correctly 60 % of carcasses in the class colour assigned by the assessors. In fact, 99% of male and 96% of female carcasses were correctly assigned in the most common colour of veal carcasses in the Spanish market ('pink', 5). These results indicate that on-line instrumental colour measurements on pectoralis superficialis muscle could be recommended to objectively evaluate carcass colour of commercial veal for the Spanish market.

Triangle-Free Geometric Intersection Graphs with Large Chromatic Number

Several classical constructions illustrate the fact that the chromatic number of a graph can be arbitrarily large compared to its clique number. However, until very recently, no such construction was known for intersection graphs of geometric objects in the plane. We provide a general construction that for any arc-connected compact set $X$ in $\mathbb{R}^2$ that is not an axis-aligned rectangle and for any positive integer $k$ produces a family $\mathcal{F}$ of sets, each obtained by an independent horizontal and vertical scaling and translation of $X$, such that no three sets in $\mathcal{F}$ pairwise intersect and $\chi(\mathcal{F})>k$. This provides a negative answer to a question of Gyarfas and Lehel for L-shapes. With extra conditions, we also show how to construct a triangle-free family of homothetic (uniformly scaled) copies of a set with arbitrarily large chromatic number. This applies to many common shapes, like circles, square boundaries, and equilateral L-shapes. Additionally, we reveal a surprising connection between coloring geometric objects in the plane and on-line coloring of intervals on the line.

Towards an on-line version of Ohba’s conjecture

The on-line choice number of a graph is a variation of the choice number defined through a two person game. It is at least as large as the choice number for all graphs and is strictly larger for some graphs. In particular, there are graphs G with |V(G)|=2χ(G)+1 whose on-line choice numbers are larger than their chromatic numbers, in contrast to a recently confirmed conjecture of Ohba that every graph G with |V(G)|⩽2χ(G)+1 has its choice number equal to its chromatic number. Nevertheless, an on-line version of Ohba’s conjecture was proposed in [P. Huang, T. Wong and X. Zhu, Application of polynomial method to on-line colouring of graphs, European J. Combin., 2011]: every graph G with |V(G)|⩽2χ(G) has its on-line choice number equal to its chromatic number. This paper confirms the on-line version of Ohba’s conjecture for graphs G with independence number at most 3. We also study list colouring of complete multipartite graphs K3⋆k with all parts of size 3. We prove that the on-line choice number of K3⋆k is at most 32k and present an alternate proof of Kierstead’s result that its choice number is ⌈(4k−1)/3⌉. For general graphs G, we prove that if |V(G)|⩽χ(G)+χ(G) then its on-line choice number equals the chromatic number.

Object interaction space represented in scene-selective regions

Previous work has shown that different cortical regions are sensitive to objects of differing real-world sizes (Konkle & Oliva, 2012; Mullally & Maguire, 2011; Bainbridge et al, 2012). Whereas a region in the occipito-temporal sulcus (OTS) shows small object selectivity, scene-selective regions (parahippocampal place area, PPA; retrosplenial cortex, RSC; and occipital place area, OPA) show systematically more activity for objects that are large in the world than smaller objects. What is the nature of this scene-like representation of objects? Here, we study an affordance-based object property: "interaction space". Interaction space is the area around objects that users traverse when interacting with the object. This interaction may include calculations of grasping points and surface area of contact, and is not necessarily conjoined with size. To fully deconvolve object interaction from physical size, we conducted a 2 x 2 factor design fMRI study with four conditions: 1) small one-handed objects (i.e., hairbrush), 2) large one-handed objects (i.e., umbrella), 3) small two-handed objects (i.e., hamburger), and 4) large two-handed objects (i.e., guitar). Stimuli were matched for ground truth size (based on physical sizes and weights), subjective size from an online survey, color, luminance, spectral energy, and retinal size. Results from a 2-factor ANOVA on beta values in functionally-defined ROIs show PPA, OPA, and RSC are sensitive to interaction space regardless of size, while PPA, OPA, and OTS are also sensitive to size regardless of interaction space. Importantly, effect sizes for interaction space in the PPA, OPA, and RSC were greater than those for object size, while the reverse was true for the OTS. These results show that interaction space is a perceptual object property that is represented in scene-selective regions, and suggest an overlapping interaction-based representation of objects and scenes in the brain. Meeting abstract presented at VSS 2013

Dynamic Driver Supply Voltage Scaling for Organic Light Emitting Diode Displays

Organic light emitting diode (OLED) display is a self-illuminating device that is supposed to be more power efficient than liquid crystal display (LCD). However, OLED display panels consume as much power as LCD panels due to total internal reflection. As the power consumption of the OLED panel depends on the pixel colors, most of the earlier power saving methods alter the pixel colors. In practice, such OLED power saving techniques can hardly accommodate photo viewers and movie players. This paper introduces the first OLED power saving technique that dynamically changes the supply voltage of the panel. Reduced supply voltage results in both power saving and decreased pixel luminance, but model-based color correction restores the decreased luminance with minimum color distortion. This technique is similar to dynamic backlight scaling of LCDs but is based on the unique characteristics of the OLED drivers. We provide an online color compensation algorithm using the luminance histogram. Luminance quantization in the histogram also achieves resource minimization. We develop a prototype and demonstrate the proposed OLED dynamic voltage scaling (DVS). Experimental result shows that the proposed OLED DVS saves up to 74.7% of the display power for the still images and up to 35.9% for movie clips.

Diagnosing synaesthesia with online colour pickers: Maximising sensitivity and specificity

The most commonly used method for formally assessing grapheme-colour synaesthesia (i.e., experiencing colours in response to letter and/or number stimuli) involves selecting colours from a large colour palette on several occasions and measuring consistency of the colours selected. However, the ability to diagnose synaesthesia using this method depends on several factors that have not been directly contrasted. These include the type of colour space used (e.g., RGB, HSV, CIELUV, CIELAB) and different measures of consistency (e.g., city block and Euclidean distance in colour space). This study aims to find the most reliable way of diagnosing grapheme-colour synaesthesia based on maximising sensitivity (i.e., ability of a test to identify true synaesthetes) and specificity (i.e., ability of a test to identify true non-synaesthetes). We show, applying ROC (Receiver Operating Characteristics) to binary classification of a large sample of self-declared synaesthetes and non-synaesthetes, that the consistency criterion (i.e., cut-off value) for diagnosing synaesthesia is considerably higher than the current standard in the field. We also show that methods based on perceptual CIELUV and CIELAB colour models (rather than RGB and HSV colour representations) and Euclidean distances offer an even greater sensitivity and specificity than most currently used measures. Together, these findings offer improved heuristics for the behavioural assessment of grapheme-colour synaesthesia.

Tailoring the Fulde‐Ferrell‐Larkin‐Ovchinnikov state

–to80mmtimes7mm,andcor-respondingly its thickness to 10 nm,and you have an idea about the pre-cision and control necessary to cre-ate thinfilmsin experimentslike theone published recently in Annalender Physik by Jan-Michael Kehrleand co-workers [1]. The motivationforcreatingsuchextraordinarilythinfilms over comparatively large areaswas a prediction that if a thin layerof a conventional superconductor issandwiched between two ferromag-netic films, then the superconduct-ing transition temperature of thistrilayer structure, after initially be-ing suppressed, would show a re-entrance behaviour when the thick-ness of one or both of the ferromag-neticlayers isvaried.The mechanism for such a re-entrant behaviour of the supercon-ducting critical temperature can ul-timately be traced back to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)effect. Peter Fulde and Richard Fer-rell, working at the time at the Uni-versity of Maryland, published theirarticle in August 1964 in Physical Re-view B (Ref. 3 in [1]). Independently,working at the Moscow Physico-Technical Institute, Anatoly Larkinand Yuri Ovchinnikov published inSeptember1964anarticleaboutsim-ilar effects in Zhurnal Eksperimen-tal’noi i Teoricheskoi Fiziki (whichappeared translated in March 1965in SovietPhysics JETP) (Ref.4 in[1]).Figure (online color at: www.ann-phys.org) IllustrationoftheFulde-Ferrell-Larkin-Ovchinnikov effect, leading tospatial oscillations as well as to singlet-tripletmixingofthesuperconductingpairamplitudesinaferromagnet.The main physical mechanismof the FFLO effect is described inFig. 1 (modified after [2]). Considersuperconductivity in a weakly spin-polarised ferromagnetic material.Electronic spin bands are shiftedwith respect to each other by anamount 2

On the online track assignment problem

This paper aims to start an analytical study of the computational complexity of some online shunting problems. We analyze the following problem. Consider a train station consisting of a set of parallel tracks. Each track can be approached from one side only or from both sides and the number of trains per track may be limited or not. The departure times of the trains are fixed according to a given time table. The problem is to assign a track to each train as soon as it arrives and such that it can leave the station on time without being blocked by any other train.We show that this problem can be modeled with online coloring of graphs. Depending on the constraints, the graphs can be overlap graphs (also known as circle graphs) or permutation graphs, and the coloring can be bounded or classical. This paper covers several combinations of these cases.

On-line color monitoring of solid foods during supercritical CO 2 pasteurization

An on-line color monitoring system for solid foods to be used during supercritical carbon dioxide (SC-CO 2) pasteurization was designed and tested. The experimental apparatus described here allowed for the measurement of reflectance spectra and color parameters ( L ∗, a ∗, b ∗) during (on-line) as well as before and after treatments (off-line). The results demonstrated that SC-CO 2 pasteurization applied at 12.0 MPa, 40 °C slightly affected the color of freshly cut pieces of coconut and carrot during the process performed at different treatment times (10, 20, and 30 min). Reflectance spectra of coconut, acquired on-line, showed that CO 2 influenced the color immediately upon treatment: lightness ( L ∗) changed from 86.10 ± 2.80 at 1 min to 79.57 ± 0.74 at 30 min. The decompression was demonstrated to be the critical parameter affecting the color of carrot. The off-line measurements showed that 30 min of treatment induced 38% and 22% decrease of redness ( a ∗) and yellowness ( b ∗), respectively. The proposed apparatus allowed for a non-invasive, immediate and direct monitoring of food color before, during and after SC-CO 2 pasteurization.

Max-coloring and online coloring with bandwidths on interval graphs

Given a graph G = ( V, E ) and positive integral vertex weights w : V → N , the max-coloring problem seeks to find a proper vertex coloring of G whose color classes C 1 , C 2 , …, C k , minimize ∑ i =1 k max v ∈ C i w ( v ). This problem, restricted to interval graphs, arises whenever there is a need to design dedicated memory managers that provide better performance than the general-purpose memory management of the operating system. Though this problem seems similar to the dynamic storage allocation problem, there are fundamental differences. We make a connection between max-coloring and online graph coloring and use this to devise a simple 2-approximation algorithm for max-coloring on interval graphs. We also show that a simple first-fit strategy, that is a natural choice for this problem, yields an 8-approximation algorithm. We show this result by proving that the first-fit algorithm for online coloring an interval graph G uses no more than 8 ċ χ( G ) colors, significantly improving the bound of 26 ċ χ( G ) by Kierstead and Qin [1995]. We also show that the max-coloring problem is NP-hard. The problem of online coloring of intervals with bandwidths is a simultaneous generalization of online interval coloring and online bin packing. The input is a set I of intervals, each interval i ∈ I having an associated bandwidth b ( i ) ∈ (0, 1]. We seek an online algorithm that produces a coloring of the intervals such that for any color c and any real r , the sum of the bandwidths of intervals containing r and colored c is at most 1. Motivated by resource allocation problems, Adamy and Erlebach [2003] consider this problem and present an algorithm that uses at most 195 times the number of colors used by an optimal offline algorithm. Using the new analysis of first-fit coloring of interval graphs, we show that the Adamy-Erlebach algorithm is 35-competitive. Finally, we generalize the Adamy-Erlebach algorithm to a class of algorithms and show that a different instance from this class is 30-competitive.

Rainbow Induced Subgraphs in Proper Vertex Colorings

Given a graph H we define ρ(H) to be the minimum order of a graph G such that every proper vertex coloring of G contains a rainbow induced subgraph isomorphic to H. We give upper and lower bounds for ρ(H), compute the exact value for some classes of graphs, and consider an interesting combinatorial problem connected with computation of ρ(H) for paths. A part of this research has been guided by a computer search and, accordingly, some computational results are presented. A special motivation comes from research in on-line coloring.

Novel fluctuation-based approach to optimization of frequency performance and degradation of nitride heterostructure field effect transistors

The fluctuation-based technique has been used to shed light onto the physical processes responsible for the performance of nitride heterostructure field effect transistors. A non-monotonic dependence of hot-phonon lifetime on the density of two-dimensional electron gas (2DEG) is found and interpreted in terms of plasmon-longitudinal-optical-phonon resonance. Experimental data show that the hot-phonon lifetime acquires the shortest value in the vicinity of the resonance. At a fixed 2DEG density of the 2DEG, the resonance can be tuned in with supplied electric power. The signatures of the resonance have also been resolved in frequency performance of the transistors and their degradation. In particular, the transistor operation is the fastest and the reliability is the highest when the hot-phonon lifetime is the shortest. (online colour at: www.pss-a.com) Drain current degradation (stars [8]) correlates with hot-phonon lifetime (curve).

Creating a new option for online-only research articles: PNAS Plus

Beginning in January 2011, PNAS will consider Direct Submission manuscripts for exclusive publication online. To encourage a transition in this direction, we will increase the usual page limit from 6 to 10 pages and will eliminate charges for online color images in PNAS Plus papers. All papers will still undergo rigorous peer-review prior to publication.

Comparative Analysis of On-Line Game Characters’ Costumes and Fashion Trend Color

The purpose of this study is to come up with ways that cooperate between on-line game design and fashion design by analyzing trend color and on-line game character's costume color in on-line game. As for the research methodology, First, on-line games were selected with reference to www.ranky.com. Second, 2009 SS trend color palettes suggested by Copenhagen International Fashion Fair was used as a criterion of fashion trend. Third, on-line game character's costume colors were analyzed in relation to the degree of reflection of trend and the game character's type. The results are as follows. Each on-line game character costume's colors were made in accordance with typical character types. But we can find a one-to-one correspondence between fashion trend colors and game character costume's colors. That's because both trends and character types are the results of the continuing interactions between human-beings and societies. In comparison with fashion trend colors, game character costume colors are partly raw and inharmonious. Therefore, it is necessary to apply fashion trend color in game character costume design for enhancing competitiveness in the world market.