Below are eight concepts to understand for anyone who works with color. Each of these—and more—are covered extensively in our e-book.
Color and appearance aren’t the same
Color is only one factor that contributes to the appearance of an object. Our sophisticated eye/brain combination integrates properties like texture, gloss, opacity, illumination, and background colors when we evaluate colors. That means objects with the same pigment or dye recipe might appear different if other properties are inconsistent.
Color is a function of our eyes and brain
The visible spectrum is comprised of light of various wavelengths. Cones are the photoreceptors in our eyes that are sensitive to wavelengths and allow us to see in color. Shorter waves appear to us as blue, with longer waves appearing red.
The color of objects depends upon how they absorb and reflect light rays. But ultimately, the color we see is subjective, determined by our own eyes and brain. Various environmental and biological factors can subtly affect our color perception. We’ve discussed these in a series of blog posts:
We classify colors according to common characteristics
Even a young child can identify the color red. But how do we describe particular colors within that large “red” category? What language can we use to better describe the colors we envision? How can we show the relationship of colors to each other?
Tests have determined that observers tend to organize colors according to 3 properties:
Dominant color (hue)
Intensity of the color (chroma)
Lightness of the color (lightness)
From these properties, numerous classification systems have been developed to define and organize the visible spectrum. One of the first, the Munsell color atlas, was published in 1915 and is still in use, along with several other specialized systems.
Color consistency implies quality
No matter the source of the color standard we’re trying to replicate, our attempts to match colors subjectively (using our eyesight alone) will be imprecise. This is a business problem since accurate color matching and consistent color are associated with high-quality products.
In addition to ensuring consistent color, digital color management streamlines the workflow to save businesses time and money.
Colorimetry quantifies color measurement
The experience of color requires 3 components:
A light source
To match and reproduce colors accurately, these physical factors need to be described numerically. That exercise is the science of colorimetry.
To scientifically describe color, the light source must be standardized in order to be reproducible. The characteristics of the object need to be measured as reflectance and transmittance curves. And the length of red, green, and blue light waves that reach the eye differentiates shades of color.
Datacolor spectrophotometers and accompanying color control software help users measure colors objectively.
Delta E is used to determine “acceptable colors”
While color consistency is a quality indicator, the degree to which color needs to match is a business decision. In many industries, consumers expect visually perfect color matching—especially with high-end products. For example, they might describe color differences as defects in an automobile interior or luxury item that might be acceptable in less expensive goods.
In the CIE Lab color space, the deviation between two colors is described as dE, or Delta E. It can be calculated with LCh or Lab color coordinate values of the standard and sample. But mathematical differences don’t perfectly align with human perception. We first see differences in shade, then chroma, and finally in lightness.
Book four of our new eBook series demonstrates the formulas for determining color differences and discusses color tolerances in detail.
Two types of instruments are used to measure color
The 2 categories of color measurement instruments are:
These simple, relatively inexpensive instruments provide tristimulus value for one light and one observer condition. They’re often used for quality control purposes, but can’t be used to calculate color formulas.
These instruments measure light reflected or transmitted across the visible spectrum and compare it to reference samples. They provide spectral data that can be used to calculate tristimulus values for various conditions and calculate color recipes for commercial color matching.
No matter what instrument you use, your samples must be properly prepared for measurements to be accurate. Measurements need to be consistent and reproducible. This requires that every possible variable in the process be controlled.
Develop and document your procedures. Be sure samples are representative and absolutely clean. Try to maintain consistent temperature, lighting, and humidity. Certain types of samples, such as textiles, can present special challenges.
Take advantage of Datacolor’s expertise. To learn more about these concepts and others, download our free Color Management ebook.