A Guide to Understanding Color Communication Table of Communicating Color . 2 Contents Ways to Measure Color . 3 Integrated Color – Throughout the Supply Chain . 4-5 Applications . 6 Attributes of Color Hue . 7 Chroma . 7 Lightness. 8 Scales for Measuring Color The Munsell Scale . 9 CIE Color Systems. 9-10 Chromaticity Values. 11 Expressing Colors Numerically CIELAB (L*a*b*) . 12 CIELCH (L*C*h°) . 12-13 Color Differences, Notation and Tolerancing Delta CIELAB and CIELCH. 14 CIE Color Space Notation. 15 Visual Color and Tolerancing . 15 CIELAB Tolerancing . 15 CIELCH Tolerancing . 16 CMC Tolerancing . 16-17 CIE94 Tolerancing . 18 Visual Assessment vs. Instrumental . 18 Choosing the Right Tolerance . 18 Other Color Expressions White and Yellow Indices. 19 Glossary . 20-24 © X-Rite, Incorporated 2007 1 Communicating How would you describe the color But even without such physical of this rose? Would you say it’s considerations, each observer Color yellow, sort of lemon yellow or interprets color based on personal maybe a bright canary yellow? references. Each person also verbally defines an object’s color Your perception and interpretation differently. of color are highly subjective. Eye fatigue, age and other physiolog- As a result, objectively communi- ical factors can influence your cating a particular color to color perception. someone without some type of standard is difficult. There also must be a way to compare one color to the next with accuracy. The solution is a measuring instru- ment that explicitly identifies a color. That is, an instrument that differentiates a color from all others and assigns it a numeric value. 2 Ways to Today, the most commonly used not reflect back to the eye. A 0/45 instruments for measuring color instrument, more effectively than Measure Color are spectrophotometers. any other, will remove gloss from the measurement and measure the Spectro technology measures appearance of the sample exactly reflected or transmitted light at as the human eye would see it. many points on the visual spec- trum, which results in a curve. Since the curve of each color is as Multi-Angle unique as a signature or finger- print, the curve is an excellent tool In the past 10 or so years, car for identifying, specifying and makers have experimented with matching color. special effect colors. They use special additives such as mica, Sample The following information can help pearlescent materials, ground up Viewing Specular you to understand which type of seashells, microscopically coated Port Port instrument is the best choice for colored pigments and interference 8˚ 8˚ S specific applications. p pigments to produce different Reference h e Beam r colors at different angles of view. e Port Spherical Large and expensive goniometers were traditionally used to measure Spherically based instruments these colors until X-Rite introduced have played a major roll in formula- a battery-powered, hand-held, tion systems for nearly 50 years. multi-angle instrument. X-Rite Sample Being Measured Most are capable of including the portable multi-angle instruments Spherical “specular component” (gloss) while are used by most auto makers and measuring. By opening a small their colorant supply chain, world- trap door in the sphere, the “spec- wide. ular component” is excluded from Colorimeter Light Source the measurement. In most cases, databases for color formulation are more accurate when this compo- Colorimeters are not spectropho- r R e e tometers. Colorimeters are tristim- iv ce nent is a part of the measurement. ce iv e e ulus (three-filtered) devices that R r Spheres are also the instrument of choice when the sample is make use of red, green, and blue textured, rough, or irregular or filters that emulate the response of approaches the brilliance of a first- the human eye to light and color. In surface mirror. Textile manufac- some quality control applications, these tools represent the lowest Sample Being Measured turers, makers of roofing tiles or acoustic ceiling materials would all cost answer. Colorimeters cannot 0/45 likely select spheres as the right compensate for metamerism (a tool for the job. shift in the appearance of a sample due to the light used to illu- minate the surface). As colorime- 0/45 (or 45/0) ters use a single type of light (such 45˚ Light 25˚ Source as incandescent or pulsed xenon) 15˚ 75˚ No instrument “sees” color more and because they do not record Specular like the human eye than the 0/45. the spectral reflectance of the This simply is because a viewer media, they cannot predict this 110˚ does everything in his or her power shift. Spectrophotometers can to exclude the “specular compo- compensate for this shift, making 45˚ 45˚ nent” (gloss) when judging color. spectrophotometers a superior When we look at pictures in a Sample Being Measured choice for accurate, repeatable glossy magazine, we arrange color measurement. Multi-angle ourselves so that the gloss does 3 Integrated Since color is a key element of a consumer's buying decisions, how Color – do you handle color consistency and quality in a global environment? Throughout the How do you keep in step with Supply Chain consumer color preferences while ensuring color options are available and easy to reproduce? The solu- tion: X-Rite color measurement technology. Accurate Color. On Time. Every Time. Whether you're working with When you streamline your work- coatings, plastics or textiles, flow system, it can greatly reduce X-Rite understands the challenges the complexity of your supply unique to your business. Because chain. With a digital supply chain customer needs—not off-the-shelf solution for color control, you can products—drive the solutions we shift color management responsi- bring, our industry experts take the bilities to your organization. This time to understand your business. means you control color data work- The unique combination of X-Rite's flow. The result: data flows faster, technology, our vertically integrated which provides the information manufacturing capabilities and the needed to optimize choice of industry's largest global presence suppliers, and respond quickly to allows us to invent and adapt specific market pressures. solutions for you, wherever you are. 4 Controlling Color throughout the Process X-Rite's product portfolio offers solutions which connect color accurately throughout the entire process. Our solutions save you money by reducing scrap, produc- tion downtime, off-color product shipments and rework. We simplify X-Rite is a global leader in color the process of managing color measurement, management and through-out your global supply communication solutions, and can chain, whether with multiple help you get the right color, every locations or at a single facility, time, from the earliest stages of helping you protect the quality production to final product shipment. of corporate brands. Offering a broad range of benchtop, Calibrated, portable or non-contact systems, On-Screen Color X-Rite instruments can be found on the desktop, in retail settings, in X-Rite offers the only color for- laboratories or on production lines, mulation and quality assurance all managing color reliably and software to use the International accurately. Your total solution Color Consortium’s (ICC) standard includes software that enhances device profiles for on-screen color. instrument functionality by adding This means that colors will be quality control, profiling functions, consistently displayed on different color matching, or color manage- computers, so long as ICC profiles ment packages. Complimented are used. Use X-Rite monitor with our Macbeth Lighting offering optimizers and auto-scan densito- and visual evaluation tools from meters for complete color calibration Munsell Color, X-Rite offers the and control on computers, printers complete portfolio for all of your and scanners. color needs. 5 Applications Spectrophotometry’s applications • Corporate logo standardization are seemingly boundless. Color- matching measurements are made • Color testing of inks every day by those comparing a • Color control of paints reproduced object to a reference point. Spectrophotometry-assisted • Control of printed colors on color measurement can be useful packaging material and labels in areas such as: • Color control of plastics and textiles throughout the development and manufacturing process • Finished products like printed cans, clothing, shoes, automobile components, plastic components of all types 6 Attributes Each color has its own distinct Hue appearance, based on three of Color elements: hue, chroma and value When asked to identify the color of (lightness). By describing a color an object, you’ll most likely speak using these three attributes, you first of its hue. Quite simply, hue is can accurately identify a particular how we perceive an object’s color color and distinguish it from any — red, orange, green, blue, etc. other. The color wheel in Figure 1 shows the continuum of color from one hue to the next. As the wheel illus- trates, if you were to mix blue and green paints, you would get blue- green. Add yellow to green for Yellow yellow-green, and so on. Chroma Chroma describes the vividness or Green Red dullness of a color — in other words, how close the color is to either gray or the pure hue. For example, think of the appearance of a tomato and a radish. The red of Blue the tomato is vivid, while the radish appears duller. Figure 2 shows how chroma changes as we move from center to Figure 1: Hue the perimeter. Colors in the center are gray (dull) and become more saturated (vivid) as they move Less Chroma More toward the perimeter. Chroma also is known as saturation. oma Chr (Saturation) Figure 2: Chromaticity 7 Attributes of Color continued Lightness The luminous intensity of a color — i.e., its degree of lightness — is called its value. Colors can be classified as light or dark when comparing their value.