scholarly journals Basic Mathematics of Color Space Invariants

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Mutual Influence ◽  
Color Space ◽  
Three Dimensional ◽  
Analytical Description ◽  
Color Management ◽  
Tone Reproduction ◽  
Initial Color ◽  
Printing Processes ◽  
Cie Lab ◽  
Color Channels

Color management in printing processes has been traditionally based on an analysis of the behavior of tone reproduction curves (TRC) calculated for the initial color channels. The tone curves, as well as, the color channels, are considered separately. This approach does not take into account the mutual influence of colorants when they overlap. We propose replacing two-dimensional tone reproduction curves with three-dimensional gradation trajectories in the CIE Lab metric space. When two colors overlap, one considers the space between two gradation trajectories that forms a gradation surface. These objects are described using the apparatus of differential geometry of spatial curves and surfaces, respectively, and are also invariants of color spaces. In this paper, we offer their analytical description.

Three-Dimensional Color Gamut Visualization of Digital Output Device Based on ICC Profile

2012 ◽  
Vol 262 ◽  
pp. 36-39 ◽  
Author(s):  
Yun Hui Luo ◽  
Mao Hai Lin
Keyword(s):  
Dimensional Space ◽  
Color Space ◽  
Three Dimensional ◽  
Color Gamut ◽  
Digital Output ◽  
Gamut Mapping ◽  
Output Device ◽  
High Quality Image ◽  
Image Appearance ◽  
Cie Lab

As color gamut of digital output device greatly affects image appearance, accurate and effective gamut description for output device is intensively required for developing high-quality image reproduction technique based on gamut mapping. In this paper, we present a novel method to determine color gamut of output device by using a specific 3D reconstruction technology and device ICC profile. First, we populate the device color space by uniform sampling in the RGB 3-Dimensional space, and convert these sampling points to CMYK color space. Then, we work out the CIE LAB value of these points according to the ICC profile of output device. At last, in CIE LAB color space the boundary of these points is determined by using a gamut boundary descriptor based on Ball-Pivoting Algorithm (BPA) proposed by Bernardini. Compared with the results generated by ICC3D, our proposed method can compute device gamut more efficiently and at the same time give a more accurate gamut description of the output device. It will be help to develop effective gamut mapping algorithms for color reproduction.

scholarly journals Mathematics and practice of color space invariants by the example of determining the gray balance for a digital printing system

2020 ◽  
Vol 44 (1) ◽  
pp. 117-126 ◽  
Author(s):  
D.A. Tarasov ◽  
O.B. Milder
Keyword(s):  
Color Space ◽  
Analytical Description ◽  
Digital Printing ◽  
Mutual Transformation ◽  
Color Spaces ◽  
Practical Application ◽  
Printing System ◽  
Cie Lab ◽  
Electrophotographic Printing ◽  
Spatial Curves

In modern printing, a large number of tasks are associated with the mutual transformation of color spaces. In particular, the most common pair of hardware-dependent color spaces is RGB and CMYK, the mutual transformation of colors in which is ambiguous, which creates significant problems in color reproduction. To solve this problem, we propose using color space invariants — gradation trajectories and gradation surfaces, which are analogs of gradation curves for initial colorants and their binary overlays, constructed in the absolute color space of the CIE Lab. Invariants are introduced on the basis of the mathematical apparatus of the differential geometry of spatial curves and surfaces. Practical application of color space invariants involves certain difficulties associated with their complex analytical description; moreover, for most practical problems, the high accuracy of the model is redundant. For the practical application of invariants, we propose a simpler approach using natural color sampling in digital printing systems. As an example, the procedure for determining the gray balance for an electrophotographic printing press is given.

scholarly journals The Application of Machine Learning for Cultivar Discrimination of Sweet Cherry Endocarp

Agriculture ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 6
Author(s):  
Ewa Ropelewska
Keyword(s):  
Sweet Cherry ◽  
Color Space ◽  
Geometric Parameters ◽  
Geometric Features ◽  
Color Spaces ◽  
Discriminative Models ◽  
Sweet Cherries ◽  
Rgb Color Space ◽  
Cultivar Discrimination ◽  
Color Channels

The aim of this study was to evaluate the usefulness of the texture and geometric parameters of endocarp (pit) for distinguishing different cultivars of sweet cherries using image analysis. The textures from images converted to color channels and the geometric parameters of the endocarp (pits) of sweet cherry ‘Kordia’, ‘Lapins’, and ‘Büttner’s Red’ were calculated. For the set combining the selected textures from all color channels, the accuracy reached 100% when comparing ‘Kordia’ vs. ‘Lapins’ and ‘Kordia’ vs. ‘Büttner’s Red’ for all classifiers. The pits of ‘Kordia’ and ‘Lapins’, as well as ‘Kordia’ and ‘Büttner’s Red’ were also 100% correctly discriminated for discriminative models built separately for RGB, Lab and XYZ color spaces, G, L and Y color channels and for models combining selected textural and geometric features. For discrimination ‘Lapins’ and ‘Büttner’s Red’ pits, slightly lower accuracies were determined—up to 93% for models built based on textures selected from all color channels, 91% for the RGB color space, 92% for the Lab and XYZ color spaces, 84% for the G and L color channels, 83% for the Y channel, 94% for geometric features, and 96% for combined textural and geometric features.

scholarly journals Finite element solution of the three-dimensional system of equations of heat dynamics of friction and wear during single braking

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880864 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Mutual Influence ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Dimensional System ◽  
System Of Equations ◽  
Sliding Velocity ◽  
Flash Temperature ◽  
Disk Brake ◽  
Discrete Contact

A three-dimensional numerical model of a disk brake to study temperature on a discrete contact of rough surfaces has been developed. It includes the system of equations formulated based on thermotribological postulates of heat dynamics of friction and wear with mutual influence of contact pressure, velocity, properties of materials, and temperature. Two approaches of calculation of the flash temperature and its influence on the maximum temperature during a single braking application were studied. Changes in the contact temperature, sliding velocity, and the thermomechanical wear during braking were shown and discussed. It was found that two of the examined variants of calculation of the flash temperature agree well for the three considered materials of the brake pads combined with the cast iron disk, at each initial sliding velocity in the range from 5 to 20 m s−1.

Peaked Encoding of Relative Luminance in Macaque Areas V1 and V2

2005 ◽  
Vol 93 (3) ◽  
pp. 1620-1632 ◽  
Author(s):  
Xinmiao Peng ◽  
David C. Van Essen
Keyword(s):  
Light Adaptation ◽  
Spatial Configuration ◽  
Color Space ◽  
Three Dimensional ◽  
Luminance Level ◽  
Adaptation Level ◽  
Luminance Change ◽  
Color Preferences ◽  
Related Information ◽  
Early Visual Cortex

It is widely presumed that throughout the primate visual pathway neurons encode the relative luminance of objects (at a given light adaptation level) using two classes of monotonic function, one positively and the other negatively sloped. Based on computational considerations, we hypothesized that early visual cortex also contains neurons preferring intermediate relative luminance values. We tested this hypothesis by recording from single neurons in areas V1 and V2 of alert, fixating macaque monkeys during presentation of a large, spatially uniform patch oscillating slowly in luminance and surrounded by a static texture background. A substantial subset of neurons responsive to such low spatial frequency luminance stimuli in both areas exhibited prominent and statistically reliable response peaks to intermediate rather than minimal or maximal luminance values. When presented with static patches of different luminance but of the same spatial configuration, most neurons tested retained a preference for intermediate relative luminance. Control experiments using luminance modulation at multiple low temporal frequencies or reduced amplitude indicate that in the slow luminance-oscillating paradigm, responses were more strongly modulated by the luminance level than the rate of luminance change. These results strongly support our hypothesis and reveal a striking cortical transformation of luminance-related information that may contribute to the perception of surface brightness and lightness. In addition, we tested many luminance-sensitive neurons with large chromatic patches oscillating slowly in luminance. Many cells, including the gray-preferring neurons, exhibited strong color preferences, suggesting a role of luminance-sensitive cells in encoding information in three-dimensional color space.

Numerical Comparative Analysis of In-Cylinder Tumble Flow Structures in Small PFI Engines Equipped by Heads Having Different Shapes and Squish Areas

2012 ◽  
Author(s):  
Stefania Falfari ◽  
Gian Marco Bianchi ◽  
Luca Nuti
Keyword(s):  
Flow Structure ◽  
Mutual Influence ◽  
Ignition Time ◽  
Three Dimensional ◽  
Valve Lift ◽  
Spark Plug ◽  
Piston Valve ◽  
Cylinder Flow ◽  
Roof Angle ◽  
Motorcycle Engine

For increasing the thermal engine efficiency, faster combustion and low cycle-to-cycle variation are required. In PFI engines the organization of in-cylinder flow structure is thus mandatory for achieving increased efficiency. In particular the formation of a coherent tumble vortex with dimensions comparable to engine stroke largely promotes proper turbulence production extending the engine tolerance to dilute/lean mixture. For motorbike and scooter applications, tumble has been considered as an effective way to further improve combustion system efficiency and to achieve emission reduction since layout and weight constraints limit the adoption of more advanced concepts. In literature chamber geometry was found to have a significant influence on bulk motion and turbulence levels at ignition time, while intake system influences mainly the formation of tumble vortices during suction phase. The most common engine parameters believed to affect in-cylinder flow structure are: 1. Intake duct angle; 2. Inlet valve shape and lift; 3. Piston shape; 4. Pent-roof angle. The present paper deals with the computational analysis of three different head shapes equipping a scooter/motorcycle engine and their influence on the tumble flow formation and breakdown, up to the final turbulent kinetic energy distribution at spark plug. The engine in analysis is a 3-valves pent-roof motorcycle engine. The three dimensional CFD simulations were run at 6500 rpm with AVL FIRE code on the three engines characterised by the same piston, valve lift, pent-roof angle and compression ratio. They differ only in head shape and squish areas. The aim of the present paper is to demonstrate the influence of different head shapes on in-cylinder flow motion, with particular care to tumble motion and turbulence level at ignition time. Moreover, an analysis of the mutual influence between tumble motion and squish motion was carried out in order to assess the role of both these motions in promoting a proper level of turbulence at ignition time close to spark plug in small 3-valves engines.

scholarly journals Embracing 3D Printing

2015 ◽  
Vol 137 (08) ◽  
pp. 42-45
Author(s):  
Mike Vasquez
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Product Line ◽  
Three Dimensional Objects ◽  
Clear Vision ◽  
Materials Used ◽  
Save Energy ◽  
High Level ◽  
Printing Processes ◽  
Lower Material

This article reviews the challenges for companies while adopting three-dimensional (3D) printing technology. A big challenge for companies figuring out whether they need to invest in 3-D printing is the different types of printing systems available in the market. At a high level, there are seven different families of 3-D printing processes. Each of the seven technologies is differentiated by the materials used and how the materials are fused together to create three-dimensional objects. Another barrier is that most companies have not yet found it viable to put the processes in place to incorporate the change in design, engineering, and manufacturing production that is required. Not only capital funds are needed to purchase machines, but to effectively use the technology to create a sellable product, one also needs to have a targeted product line and clear vision of the ways that 3-D printing can help lower material costs, save energy, and simplify manufacturing and assembly.

Entrainment and growth of vortical disturbances in the channel-entrance region

2021 ◽  
Vol 927 ◽  
Author(s):  
Pierre Ricco ◽  
Claudia Alvarenga
Keyword(s):  
Initial Conditions ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Analytical Description ◽  
Reynolds Numbers ◽  
Boundary Region ◽  
Shear Layers ◽  
Base Flow ◽  
Open Boundary ◽  
Classical Stability

The entrainment of free-stream unsteady three-dimensional vortical disturbances in the entry region of a channel is studied via matched asymptotic expansions and by numerical means. The interest is in flows at Reynolds numbers where experimental studies have documented the occurrence of intense transient growth, despite the flow being stable according to classical stability analysis. The analytical description of the vortical perturbations at the channel mouth reveals how the oncoming disturbances penetrate into the wall-attached shear layers and amplify downstream. The effects of the channel confinement, the streamwise pressure gradient and the viscous/inviscid interplay between the oncoming disturbances and the boundary-layer perturbations are discussed. The composite perturbation velocity profiles are employed as initial conditions for the unsteady boundary-region perturbation equations. At a short distance from the channel mouth, the disturbance flow is mostly confined within the shear layers and assumes the form of streamwise-elongated streaks, while farther downstream the viscous disturbances permeate the whole channel although the base flow is still mostly inviscid in the core. Symmetrical disturbances exhibit a more significant growth than anti-symmetrical disturbances, the latter maintaining a nearly constant amplitude for several channel heights downstream before growing transiently, a unique feature not reported in open boundary layers. The disturbances are more intense as the frequency decreases or the bulk Reynolds number increases. We compute the spanwise wavelengths that cause the most intense downstream growth and the threshold wall-normal wavelengths below which the perturbations are damped through viscous dissipation.

Cellular Automata for Imaging, Art, and Video

2003 ◽  
Author(s):  
Joy V. Hughes
Keyword(s):  
Cellular Automata ◽  
State Space ◽  
Color Space ◽  
Three Dimensional ◽  
Difficult Problem ◽  
Special Effects ◽  
Color Wheel ◽  
Distorted Version ◽  
Artistic Medium ◽  
A Cell

The techniques known as Cellular Automata (CA) can be used to create a variety of visual effects. As the state space for each cell, 24-bit photo realistic color was used. Several new state transition rules were created to produce unusual and beautiful results, which can be used in an interactive program or for special effects for images or videos. This chapter presents a technique for applying CA rules to an image at several different levels of resolution and recombining the results. A “soft” artistic look can result. The concept of “targeted” CAs is introduced. A targeted CA changes the value of a cell only if it approaches a desired value using some distance metric. This technique is used to transform one image into another, to transform an image to a distorted version of itself, and to generate fractals. The author believes that the techniques presented can form the basis for a new artistic medium that is partially directed by the artist and partially emergent. Images and animations from this work are posted on the World Wide Web at (http://www.scruznet.com/~hughes/CA.html). All cellular automata (CA) operate on a space of discrete states. The simplest CAs, such as the Game of Life, use a 1-bit state space. Most modern personal computers represent color as a 24-bit value, allowing for approximately 16 million possible colors. The work presented in this chapter uses a 24-bit color space that is represented in a 32-bit-long integer. This color space can be conceptualized as a three-dimensional bounded continuous vector space. Often, it is desirable to work with in the HSV (Hue, Saturation, Value) color space. Some of the rules encode the value (luminance) of a cell in the otherwise unused 8 high-order bits of a 32-bit word. The hue and saturation can be estimated “on the fly” with simple, fast algorithms. The hue is represented as an angle on the color wheel. For some rules, it is necessary to know the “distance” between two colors. Estimating the distance in perceptual space would be a difficult problem, as it would be dependent on the monitor used and the gamma exponent applied for a particular setup.

Both Hands’ Fingers’ Angle Calculation from Live Video

2012 ◽  
Vol 2 (2) ◽  
pp. 1-11 ◽  
Author(s):  
Ankit Chaudhary ◽  
Jagdish L. Raheja ◽  
Karen Das ◽  
Shekhar Raheja
Keyword(s):  
Gesture Recognition ◽  
Color Space ◽  
Three Dimensional ◽  
Region Of Interest ◽  
Natural Computing ◽  
Robotic Hand ◽  
Hsv Color Space ◽  
Binary Format ◽  
Novel Method ◽  
Angle Calculation

In the last few years gesture recognition and gesture-based human computer interaction has gained a significant amount of popularity amongst researchers all over the world. It has a number of applications ranging from security to entertainment. Gesture recognition is a form of biometric identification that relies on the data acquired from the gesture depicted by an individual. This data, which can be either two-dimensional or three-dimensional, is compared against a database of individuals or is compared with respective thresholds based on the way of solving the riddle. In this paper, a novel method for angle calculation of both hands’ bended fingers is discussed and its application to a robotic hand control is presented. For the first time, such a study has been conducted in the area of natural computing for calculating angles without using any wired equipment, colors, marker or any device. The system deploys a simple camera and captures images. The pre-processing and segmentation of the region of interest is performed in a HSV color space and a binary format respectively. The technique presented in this paper requires no training for the user to perform the task.

Sign in / Sign up

Export Citation Format

Share Document