DOCSLIB.ORG

Between Additive and Subtractive Color Mixings: Intermediate Mixing Models Lionel Simonot, Mathieu Hébert

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Between Additive and Subtractive Color Mixings: Intermediate Mixing Models Lionel Simonot, Mathieu Hébert Between additive and subtractive color mixings: intermediate mixing models Lionel Simonot, Mathieu Hébert To cite this version: Lionel Simonot, Mathieu Hébert. Between additive and subtractive color mixings: intermediate mixing models. Journal of the Optical Society of America. A Optics, Image Science, and Vision, Optical Society of America, 2013, 31 (1), pp.58-66. 10.1364/JOSAA.31.000058. hal-00962256 HAL Id: hal-00962256 https://hal.archives-ouvertes.fr/hal-00962256 Submitted on 20 Sep 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 58 J. Opt. Soc. Am. A / Vol. 31, No. 1 / January 2014 L. Simonot and M. Hébert Between additive and subtractive color mixings: intermediate mixing models Lionel Simonot1,* and Mathieu Hébert2 1Institut Pprime, Université de Poitiers, CNRS UPR 3346, Département Physique et mécanique des matériaux, SP2MI, BP 30179, 86962 Chasseneuil, Futuroscope Cedex, France 2Université de Lyon, Université Jean Monnet de Saint-Etienne, CNRS UMR5516, Laboratoire Hubert Curien, F-42000 Saint-Etienne, France *Corresponding author: lionel.simonot@univ‑poitiers.fr Received July 18, 2013; revised October 16, 2013; accepted November 11, 2013; posted November 13, 2013 (Doc. ID 194145); published December 5, 2013 The color rendering of superposed coloring components is often an issue either to predict or to simulate the ap- pearance of colored surfaces. In graphical software, for example, transparence options are available to display different layouts on top of each other. With two colored layers, tuning the transparency of the top layer enables transitioning continuously from the color of this top layer to the color of the bottom layer. However, these options based very often only on additive color mixing offer limited transitions between two base colors. It would be advantageous to introduce more advanced options, providing, for example, realistic renderings of superposed paint layers. This is the aim of the present study, where simple models are proposed to create intermediate con- figurations between additive and subtractive color mixings. These models rely on the spectral power distribution of a finite set of primaries with given proportions. They may be extended to RGB color reflective or transmissive systems if the red, green, and blue wavebands do not overlap each other. An additional parameter is introduced to tune the proportions of additive and subtractive mixings, each type of mixing being based on its set of primaries. Various simulations of color mixings are presented, illustrating the possibilities offered by this model in addition to those permitted by the purely additive and subtractive mixings. © 2013 Optical Society of America OCIS codes: (300.6550) Spectroscopy, visible; (330.1690) Color; (330.1730) Colorimetry. http://dx.doi.org/10.1364/JOSAA.31.000058 1. INTRODUCTION subtractive. The ideal additive and subtractive mixing are in- What is the result of the mixing between different colors? The cluded in these new mixing laws as limit cases. The mixing answer of course depends on the relative proportions of the laws deal with spectral data with a minimum of three spectral different primaries, but also on the type of color mixing. In bands. The models can also be satisfyingly extended to RGB additive mixing, color is obtained by mixing lights with differ- color systems in the case in which the wavebands defining the ent spectral power distributions either by projection of col- red, green, and blue channels do not overlap each other. ored light beams or by juxtaposition of small colored areas as in displays. The colors are synthesized by mixing at least 2. DEFINITION OF COLORS three primaries, generally not more: red, green, and blue. In The color P of a surface comes from the interpretation by the subtractive mixing, colors are obtained by superposing col- human visual system of the light signal reflected or transmit- ored layers behaving as spectral filters for white light, like ted by the surface, especially its spectral distribution denoted the inks in half-tone printing. Three primaries are commonly Pλ. The number N of wavebands depends on the measurement used: cyan, magenta, and yellow. The distinction between system. At least three wavebands in the visible range are additive and subtractive color mixing was first exposed by needed to define colors, but N may be larger, or much larger Helmholtz [1] in 1860 in order to clarify the previous confusion in the cases of multi and hyper-spectral systems. By normal- between light and colorant mixture. In many color ordering izing the measured spectrum by a reference spectrum consid- systems [2] and in the habits of painters even today, the ered as the maximum signal (direct incident light for primaries are often red, yellow, and blue. There is a large transmittance measurements, and light scattered by a white dispersion in the precise definition of these primaries depend- standard for reflectance measurements), the spectrum satis- ing on the available pigments. In practice, e.g., for painting, the fies the property mixing laws are complex to simulate. Nevertheless, the result- ing color in general stays between those predicted by the ideal 0 ≤ Pλ ≤ 1 ∀ λ: (1) additive and by the ideal subtractive mixing. In half-tone printing, Yule and Nielsen [3] defined such an intermediate The color P can be considered as a vector in an N- empirical mixing law. In this paper, we propose other easily dimensional space (with N ≥ 3), and Pλ are its coordinates. understandable color mixing laws governed by intuitive From the spectral values, the color can be defined more con- parameters: the component proportions and a mixing param- ventionally by using the standardization of the CIE [4,5]. The eter indicating whether the color synthesis is additive or CIEXYZ tristimulus values are obtained by multiplying the 1084-7529/14/010058-09$15.00/0 © 2014 Optical Society of America L. Simonot and M. Hébert Vol. 31, No. 1 / January 2014 / J. Opt. Soc. Am. A 59 spectral value Pλ, the standardized illuminant radiance spec- decomposed into different subareas and/or different sub- trum Sλ, and each of the matching color functions x¯ λ, y¯ λ, layers as shown in Fig. 1. The following assumptions are made and z¯λ, and then summing the resulting spectrum over the regarding the optical properties of subareas and sublayers: visible wavelength domain: — They do not scatter light and therefore satisfy Beer– 8 P – ¯ Lambert Bouguer law (i.e., the transmittance of superposed < X kPλ PλSλxλ ’ ¯ components is the product of the component s individual : Y kPλ PλSλyλ ; 2 transmittances). ¯ Z k λ PλSλzλ — The multiple reflections of light between superposed components are not taken into account. 100 where the factor k is a normalization factor giving Y — Lateral propagation of light between neighboring subar- 1 for the reference whose spectral values are Pλ for every eas can be neglected. waveband. For object colors, the CIELAB color space is classically used. The coordinates—lightness L, green/red These strong assumptions allow defining some ideal coordinate a, and blue/yellow coordinate b—can be derived mixing laws respecting the previously stated rules. from the CIEXYZ tristimulus values by nonlinear rela- Let us denote as ai the fractional areas of the subareas, and tions [4,5]. as ti the fractional thickness of the sublayers. In purely additive mixing, the color cell is composed of N juxtaposed filters of unit thickness that thus represent 3. COLOR MIXING RULES c the primaries Pi [Fig. 1(a) for Nc 3]. The fractional areas P ∈ 1 … Let us consider Nc primaries i with i f ; ;Ncg. Nc is com- of these subareas, ai, satisfying monly 2 (binary mixing) or 3 (ternary mixing). But Nc can be XNc larger to precisely model color reproduction systems; for ex- ai 1; (5) ample, for RGB displays, the black background can be num- i1 bered among the primaries (N 4), or in a CMY trichromy, c are the proportions c of the mixing. The additive mixing is a the bare paper, or the paper with one, two, or three ink layers, i linear combination of the primary spectral values: are all considered as primaries (Nc 8). Several color mixing N configurations can be defined from the spectra Pi;λ. The Xc following rules are an attempt to formalize some of these Pλ ciPi;λ (6) configurations. i1 P Let us denote as the color obtained by mixing the Nc with ci ai. primaries Pi with respective proportions ci satisfying the conditions 0 ≤ ci ≤ 1 (3) and XN ci 1: (4) i1 • Rule 1: The spectral values Pλ attached to P satisfy the property (1). • Rule 2: The proportions ci should have the same influ- ence on Pλ for every waveband λ in the visible spectrum. • Rule 3: The mixing operation is commutative: P is inde- pendent of the ordering of the components in the mixing. • Rule 4: By considering the mixing between two colors with respective proportions c and 1 − c, the relation Pλ c is continuous and monotonous with c in every waveband λ. Rule 4 induces the following logical property: the color re- sulting from the mixing of color P1 with itself is again color P1 for every proportion c. It is important to note that counterexamples can be found where these rules are not satisfied, e.g., color mixing with photoluminescence effects where light emission at one wavelength greatly depends on the absorption at a smaller wavelength.
Load more

Recommended publications
  • Color Gamut of Halftone Reproduction*
    Color Gamut of Halftone Reproduction* Stefan Gustavson†‡ Department of Electrical Engineering, Linkøping University, S-581 83 Linkøping, Sweden Abstract tern then gets attenuated once more by the pattern of ink that resides on the surface, and the finally reflected light Color mixing by a halftoning process, as used for color is the result of these three effects combined: transmis- reproduction in graphic arts and most forms of digital sion through the ink film, diffused reflection from the hardcopy, is neither additive nor subtractive. Halftone substrate, and transmission through the ink film again. color reproduction with a given set of primary colors is The left-hand side of Fig. 2 shows an exploded view of heavily influenced not only by the colorimetric proper- the ink layer and the substrate, with the diffused reflected ties of the full-tone primaries, but also by effects such pattern shown on the substrate. The final viewed image as optical and physical dot gain and the halftone geom- is a view from the top of these two layers, as shown to etry. We demonstrate that such effects not only distort the right in Fig. 2. The dots do not really increase in the transfer characteristics of the process, but also have size, but they have a shadow around the edge that makes an impact on the size of the color gamut. In particular, a them appear larger, and the image is darker than what large dot gain, which is commonly regarded as an un- would have been the case without optical dot gain. wanted distortion, expands the color gamut quite con- siderably.
    [Show full text]
  • Color Mixing Ratios
    Colour Mixing: Ratios Color Theory with Tracy Moreau Learn more at DecoArt’s Art For Everyone Learning Center www.tracymoreau.net Primary Colours In painting, the three primary colours are yellow, red, and blue. These colors cannot be created by mixing other colours. They are called primary because all other colours are derived from them. Mixing Primary Colours Creates Secondary Colours If you combine two primary colours you get a secondary colour. For example, red and blue make violet, yellow and red make orange, and blue and yellow make green. If you mix all of the primary colours together you get black. The Mixing Ratio for Primary Colours To get orange, you mix the primary colours red and yellow. The mixing ratio of these two colours determines which shade of orange you will get after mixing. For example, if you use more red than yellow you will get a reddish-orange. If you add more yellow than red you will get a yellowish-orange. Experiment with the shades you have to see what you can create. Try out different combinations and mixing ratios and keep a written record of your results so that you can mix the colours again for future paintings. www.tracymoreau.net Tertiary Colours By mixing a primary and a secondary colour or two secondary colours you get a tertiary colour. Tertiary colours such as blue-lilac, yellow-green, green-blue, orange-yellow, red-orange, and violet-red are all created by combining a primary and a secondary colour. The Mixing Ratios of Light and Dark Colours If you want to darken a colour, you only need to add a small amount of black or another dark colour.
    [Show full text]
  • Color Mixing Challenge
    COLOR MIXING CHALLENGE Target age group: any age Purpose of activity: to experiment with paint and discover color combinations that will make many different shades of the basic colors Materials needed: copies of the pattern page printed onto heavy card stock paper, small paint brushes, paper towels, paper plates to use as palettes (or half-sheets of card stock), a bowl of water to rinse brushes, acrylic paints in these colors: red, blue, yellow, and white (NOTE: Try to purchase the most “true” colors you can-- a royal blue, a true red, a medium yellow.) Time needed to complete activity: about 30 minutes (not including set-up and clean-up time) How to prepare: Copy (or print out) a pattern page for each student. Give each student a paper plate containing a marble-sized blob of red, blue, yellow and white. (Have a few spare plates available in case they run out of mixing space on their fi rst plate.) Also provide a paper towel and a bowl of rinse water. If a student runs out of a particular color of paint, give them a dab more. This will avoid wasting a lot of paint. (If you let the students fi ll their own paints, they will undoubtedly waste a lot of paint. In my experience, students almost always over-estimate how much paint they need.) What to do: It’s up to you (the adult in charge) how much instruction to give ahead of time. You may want to discuss color theory quite a bit, or you may want to emphasize the experimental nature of this activity and let the students discover color combinations for themselves.
    [Show full text]
  • Computational RYB Color Model and Its Applications
    IIEEJ Transactions on Image Electronics and Visual Computing Vol.5 No.2 （2017） -- Special Issue on Application-Based Image Processing Technologies -- Computational RYB Color Model and its Applications Junichi SUGITA† (Member), Tokiichiro TAKAHASHI†† (Member) †Tokyo Healthcare University, ††Tokyo Denki University/UEI Research <Summary> The red-yellow-blue (RYB) color model is a subtractive model based on pigment color mixing and is widely used in art education. In the RYB color model, red, yellow, and blue are defined as the primary colors. In this study, we apply this model to computers by formulating a conversion between the red-green-blue (RGB) and RYB color spaces. In addition, we present a class of compositing methods in the RYB color space. Moreover, we prescribe the appropriate uses of these compo- siting methods in different situations. By using RYB color compositing, paint-like compositing can be easily achieved. We also verified the effectiveness of our proposed method by using several experiments and demonstrated its application on the basis of RYB color compositing. Keywords: RYB, RGB, CMY(K), color model, color space, color compositing man perception system and computer displays, most com- 1. Introduction puter applications use the red-green-blue (RGB) color mod- Most people have had the experience of creating an arbi- el3); however, this model is not comprehensible for many trary color by mixing different color pigments on a palette or people who not trained in the RGB color model because of a canvas. The red-yellow-blue (RYB) color model proposed its use of additive color mixing. As shown in Fig.
    [Show full text]
  • OSHER Color 2021
    OSHER Color 2021 Presentation 1 Mysteries of Color Color Foundation Q: Why is color? A: Color is a perception that arises from the responses of our visual systems to light in the environment. We probably have evolved with color vision to help us in finding good food and healthy mates. One of the fundamental truths about color that's important to understand is that color is something we humans impose on the world. The world isn't colored; we just see it that way. A reasonable working definition of color is that it's our human response to different wavelengths of light. The color isn't really in the light: We create the color as a response to that light Remember: The different wavelengths of light aren't really colored; they're simply waves of electromagnetic energy with a known length and a known amount of energy. OSHER Color 2021 It's our perceptual system that gives them the attribute of color. Our eyes contain two types of sensors -- rods and cones -- that are sensitive to light. The rods are essentially monochromatic, they contribute to peripheral vision and allow us to see in relatively dark conditions, but they don't contribute to color vision. (You've probably noticed that on a dark night, even though you can see shapes and movement, you see very little color.) The sensation of color comes from the second set of photoreceptors in our eyes -- the cones. We have 3 different types of cones cones are sensitive to light of long wavelength, medium wavelength, and short wavelength.
    [Show full text]
  • Analysis of Umberger's Theory for Subtractive Color Reproduction
    Rochester Institute of Technology RIT Scholar Works Theses 11-1-1990 Analysis of Umberger's theory for subtractive color reproduction Paul R. Bartel Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Bartel, Paul R., "Analysis of Umberger's theory for subtractive color reproduction" (1990). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. ANALYSIS OF UMBERGER'S THEORY FOR SUBTRACTIVE COLOR REPRODUCTION by PAUL R. BARTEL B.S. Warsaw Polytechnic (1981) A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the Center for Imaging Science in the College of Graphic Arts and Photography of the Rochester Institute of Technology November 1990 Signature of the Author_P_a_u_I_R_"_B_a_rt_e_I _ Center for Imaging Science Accepted by ---'--'M..:.:e::..:n..:.:d:..:.;i'-'V:...:a;;..:eo;::z:....-R:..;.a:::..v.:..;a:..:.;n...:.;iC-.- __ Coordinator, M.S. Degree Program COLLEGE OF GRAPHIC ARTS AND PHOTOGRAPHY ROCHESTER INSTITUTE OF TECHNOLOGY ROCHESTER, NEW YORK CERTIFICATE OF APPROVAL M.S. DEGREE THESIS The M.S. Degree Thesis of Paul R. Bartel has been examined and approved by the thesis committee as satisfactory for the thesis requirement for the Master of Science degree Peter G. Engeldrum, Thesis Advisor Leonard M. Carreira Dr. Roy S. Berns Date ii THESIS RELEASE PERMISSION ROCHESTER INSTITUTE OF TECHNOLOGY CENTER OF GRAPHIC ARTS AND PHOTOGRAPHY Title of Thesis ANALYSIS OF UMBERGER'S THEORY FOR SUBTRACTIVE COLOR REPRODUCTION I, PAUL R.
    [Show full text]
  • Subtractive Color Mixture Computation
    By Dennis Jarvis [CC BY-SA 2.0], via Wikimedia Commons (cropped) Subtractive Color Mixture Computation by Scott Allen Burns, Urbana, IL Published March 10, 2015; last updated May 3, 2015 Note: This is a PDF version of the web page http://scottburns.us/subtractive-color-mixture/ Overview I present an algorithm for computationally mixing screen colors (RGB colors) subtractively. The question it addresses is, "Given two colors specified by their RGB triplets, what RGB triplet should be used to represent the color that would arise if the two colors were mixed like paint colors, i.e., mixed subtractively?" The only way I can think of doing this in a rigorous way is to employ the math behind how a stimulus (a continuous spectral power distribution) enters our eyes and is transformed into a three-dimensional color sensation by our brain. Once this process has been adequately modeled, subtractive color mixture follows directly. The approach I present here is to convert the RGB colors to spectral reflectance curves, mix the curves using the weighted geometric mean, and then convert the result back to RGB. A Disclaimer The algorithm described here provides a representative model for subtractive color mixture. The way actual paints mix, for example, is highly dependent upon the particular pigments being used, as well as many other factors. Be aware that you can mix a blue and a yellow paint to get green in one case, and then mix another blue (that appears IDENTICAL to the first blue and has the same RGB value) and another yellow (appearing IDENTICAL to the first yellow, with the same RGB value) and get brown or some other color as a result! There is no way to differentiate between these two different outcomes based on the RGB values of the source colors.
    [Show full text]
  • Color Mixing…
    JUST PAINTPublished by Golden Artist Colors, Inc. / Issue 26 From Mark Golden Twenty-six issues of this technical newsletter and I am delighted to share we are still continuing the dialogue on color! After the success of Sarah Sands’ article on the ‘Subtleties of Color’ (JP 21), we recognized the value of continuing to provide more color resources for artists. The Tint & Glaze Poster was the first significant new tool for artists to come from this research. Following up on this work to create a printed color chart trying to represent real paint colors, Chris Farrell, our Creative Director and person in charge of putting together this chart, is our principle advocate that printing, no matter how carefully it’s done, cannot be a substitute Color for paint. In this issue, Chris shares the significant differences in ranges possible with commercial printing processes and Mixing… real paint. Our Director of the GOLDEN Certified You can’t get it unless you do it! Working Artist Program and author, Patti Brady, shares her painterly insights into a By Patti Brady promote them. However, each of new Modern Theory Color Mixing Set for I had been given what to me seemed these concepts, whether historical, artists, which takes just the opposite tact like the daunting task of writing contemporary or genre specific, create from Chris, in working with a limited set an article on color mixing and to a starting point that is extremely of colors to produce an enormous range of introduce the new Modern Theory helpful for the artist beginning to mixing colors.
    [Show full text]
  • Rutland™ Ink Standard Colors for Screen Printing Ink Rutland Screen Printing Ink Colors
    COLOR CARD RUTLAND™ INK STANDARD COLORS FOR SCREEN PRINTING INK RUTLAND SCREEN PRINTING INK COLORS Ready for Use Colors M3 Color Mixing System C3 Color Boosting Rutland low cure inks are non- The Rutland M3 non-phthalate Mixing System phthalate ready-for-use color finished ink color mixing system The Rutland non-phthalate color inks comprised of two barriers, is a collection of Pantone®-listed booster mixing system consists of one white ink, one black ink and colors used to create custom single pigment color concentrates 28 brilliant colors. The inks are formulations. This versatile that were developed as a means available in two series: EH high ink mixing system is ideal for of enhancing finished ink mixing opacity and EL low bleed. color matching and new color primaries to offer a darker, development. more saturated color. Rutland Standard Colors EL3399 EL2768 EL4769 EL3403 EL7574 NPT Forest Green NPT LB Bright Blue NPT LB Bright Gold NPT LB Dallas Green NPT LB Dark Brown EL2406 EL4202 EL5203 EL6399 EL6398 NPT LB Dark Navy NPT LB Gold NPT LB HO Bright Orange NPT LB HO Burgundy NPT LB HO Cardinal EL7003 EL0730 EL3401 EL1570 EL1212 NPT LB HO Peach NPT LB HO Grey NPT LB HO Lt Green NPT LB HO Purple NPT LB HO Team Violet EL7495 EL5159 EL4500 EL2589 EL2402 NPT LB HO Spice Brown NPT LB HO Team Orange NPT LB HO Vegas Gold NPT LB Lt Blue NPT LB Lt Navy EL6279 EL2449 EL2584 EL6400 EL2499 NPT LB Red NPT LB Lt Royal NPT LB Royal NPT LB Scarlet NPT LB Turquoise EL4611 EL4215 EL5202 NPT LB Yellow NPT LB Yellow RS NPT Lt Orange Rutland M3 and C3 Mixing System Colors 1440 2441 2442 2443 3443 Violet Blue #1 Blue #2 Marine Green 4449 6446 6447 1038 1018 Yellow Scarlet Red FF Fl Violet FL Magenta Rutland M3 and C3 Mixing System Colors 4042 6057 1017 1037 2065 FL Lemon FL Red FL Magenta FL Violet FL Blue 3033 4037 4041 5018 6055 FL Green FL Yellow FL Lemon FL Orange FL Pink USING THIS CHART This color selection chart is a tool to assist in selecting your requirements, Avient color experts can use your the proper screen printing ink for specific applications.
    [Show full text]
  • 8.9 Mixing Colours.Pdf
    8.9 Mixing Colours Grade 8 Activity Plan 1 Reviews and Updates 2 8.9 Mixing Colours Objectives: 1. To demonstrate the properties of white light; it’s component colors and how they can be revealed. 2. To outline the differences between additive and subtractive colour mixing. 3. To understand the colour wheel and concepts associated with it such as complimentary colours etc. Keywords/concepts: rays, beams, pigment, pixels, visible light spectrum, Isaac Newton’s color wheel, additive and subtractive colour mixing, primary and secondary colours, complimentary colours, speed and wavelength of light. Curriculum outcomes: 209-2, 209-6, 210-11, 308-8, 308-9, 308-10. Take-home product: colour wheel 3 Segment Details African Proverb and “Before one has white hairs, one must first have them Cultural Relevance black.” Wolof, Senegal (5 min.) Ask probing questions on students’ knowledge of colours. Pre-test A little light on the psychology of colours is also (10 min.) appropriate. Explain the mixture of colours in white or colourless light. Use colour viewing box. Describe process of additive Background colour mixing. Demonstrate using torches and cellophane (10 min.) paper. Detail primary additive colours. Describe subtractive colour mixing. Demonstrate with paints. Detail primary subtractive colours. Describe how filters work using the colour viewing box. Activity 1 Also endeavour to illustrate the effect of filters on the (10 min.) colours of other objects around Activity 2 Using the prism and simulation link provided, demonstrate (15 min.) that white light is made up of other component colours. Activity 3 Using a painted or printed colour wheel, illustrate additive (20 min.) colour mixing.
    [Show full text]
  • LED Color Mixing: Basics and Background
    CLD-AP38 REV 1D TECHNICAL ARTICLE LED Color Mixing: Basics and Background TABLE OF CONTENTS INTRODUCTION Introduction ...................................................................................1 This application note explains aspects of the theory and practice The Need for Color Consistency in LED Illumination ..................2 of creating color-consistent, LED-based illumination products LED Binning ...................................................................................3 and shows how to use Cree XLamp® LEDs to achieve this end. Colorimetry and Binning Basics ...................................................3 LEDs, as with all manufactured products, have material and Color-Space Basics .................................................................4 process variations that yield products with corresponding Idealized Illumination Colors – the Black Body Curve ..........7 variation in performance. LEDs are binned and packaged to MacAdam Ellipses: The Variability of Perception, Expressed balance the nature of the manufacturing process with the in Color Space .........................................................................9 needs of the lighting industry. Lighting-class LEDs are driven Partitioning the Color Space – Binning ................................11 by application requirements and industry standards, including Chromaticity Bins ..................................................................13 color consistency and color and lumen maintenance. Just as Flux Bins .................................................................................14
    [Show full text]
  • Improving Image Quality in Multi-Channel Printing – Multilevel Halftoning, Color Separation and Graininess Characterization
    Linkoping¨ Studies in Science and Technology Dissertation No. 1840 Improving image quality in multi-channel printing – multilevel halftoning, color separation and graininess characterization Paula Zitinskiˇ El´ıas Division of Media and Information Technology Linkoping¨ University, Norrkoping,¨ Sweden Norrkoping,¨ 2017 Improving image quality in multi-channel printing – multilevel halftoning, color separation and graininess characterization Copyright © Paula Zitinskiˇ El´ıas Division of Media and Information Technology Campus Norrkoping,¨ Linkoping¨ University Norrkoping,¨ Sweden ISBN: 978-91-7685-558-4 ISSN: 0345-7524 Printed in Sweden by LiU-Tryck, Linkoping,¨ 2017 Abstract Color printing is traditionally achieved by separating an input image into four channels (CMYK) and binarizing them using halftoning algorithms, in order to designate the locations of ink droplet placement. Multi-channel printing means a reproduction that employs additional inks other than these four in order to augment the color gamut (scope of reproducible colors) and reduce undesirable ink droplet visibility, so-called graininess. One aim of this dissertation has been to characterize a print setup in which both the primary inks CMYK and their light versions are used. The presented approach groups the inks, forming subsets, each rep- resenting a channel that is reproduced with multiple inks. To halftone the separated channels in the present methodology, a specific multilevel halftoning algorithm is employed, halftoning each channel to multiple lev- els. This algorithm performs the binarization from the ink subsets to each separate colorant. Consequently, the print characterization complexity remains unaltered when employing the light inks, avoiding the normal in- crease in computational complexity, the one-to-many mapping problem and the increase in the number of training samples.
    [Show full text]