Color 101

COLOR 101

What constitutes acceptable color is often very subjective. What one art director perceives and approves, another may not find suitable, and a third may not have understood completely. All is not chaos, however, because although there certainly is an art to proper digital color, there is no shortage of hard science, and reproducible results.

This section hopes to serve as a primer on professionally producing and reproducing color.

Let’s start with some basic color definitions.

First, what is color? While this question sounds simple, the answer can be quite complex because color reproduction varies from output device to output device. For example, Magenta toner on one printer may not be the same as Magenta toner on another printer.  Printers have different gamuts, environment is a factor, and substrate is an important element often overlooked.

Compensating for these differences requires standards-compliant technologies and workflows that can translate the color intent specified by the document’s creator into the appropriate color output for each device. This is the basic definition of color management.

Color is the visual sensation produced in response to selective absorption of wavelengths from visible light. This is a fancy way of saying it happens more in the brain than in the eye. The eye collects the data, and the brain interprets the data.

Color is commonly referenced using additive or subtractive models.

Additive Color: An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process starts with black or the absence of color. Color combinations of red, green and blue (RGB) are then added to achieve the desired color. Computer monitors and televisions are the most common application of additive color.  Red, Green and Blue components of the total spectrum of light combine to create the phenomena of color.

R+B+G+light  = every color

Subtractive Color: A subtractive color model begins with white or the reflection of all colors. Colorants are then added, shift the reflective values and produce the desired color. This model is used in mixing paints, dyes, inks and natural colorants to create a range of colors.

Light bounds off white (how white is white?) minus RGB values





In an additive or a subtractive model, three primary colors are needed to correlate to the three different types of color receptors (cone cells) in the human eye (trichromatic color vision). The three primary colors in the additive model are red, green and blue (RGB), while the three primary colors in the subtractive model are cyan, magenta and yellow (CMY) with blacK added to increase contrast, provide for overprinted text, and allow for adjustment of both Saturation and Brightness.

Color Standards

The International Commission on Illumination (CIE) or Commission Internationale de l’Eclairage is devoted to international cooperation on the science of color as it relates to the standards associated with measuring and quantification of color. It also defines the device independent color space in which the transformations from one device to another are performed. Since its inception 90 years ago, the CIE has been accepted as the highest authority on the subject and is recognized by the International Standards Organization (ISO) as an international standards body

The International Color Consortium or ICC is the official arbiter of color standards as they relate to the technological implementation of color conversions, quantifications and descriptions for the output devices and software used in the graphic arts industry. The ICC was established in 1993 by a group of industry vendors for the purpose of creating, promoting and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture and components. The outcome of this cooperative effort was the ICC profile specification. ICC profiles are used to describe the color capabilities of input and output devices such as monitors, scanners or printers.

ICC profiles provide a cross-platform device profile format that ensures consistent, device-independent color throughout the entire production process. Device profiles can be used to translate color data created on one device into another device’s native color space. This addresses the issue mentioned above, where toner or ink colors can vary from device to device. The acceptance of this format by operating system and graphic application vendors allows end users to transparently move profiles and images with embedded profiles among different operating systems and applications.

Regional Standards

Due to the variability of inks, papers and other elements of the print production process globally and the production differences among heatset web, coldset web (newspaper) and sheetfed printing, a number of regional color standards have emerged. The basic color science underlying these regional standards is based on ICC and CIE work. Graphic creation packages can be configured to produce files compliant with these specifications, depending on where the project will ultimately be produced. These standards include:

Specifications for Web Offset Printing (SWOP): The North American standard is largely used in newspaper, advertising and magazine production. It ensures color consistency for ads. This standard defines the colors of the ink sets used and the desired densities of the inks on the page. The standard is important to advertisers, who need to ensure brand integrity in their ads and other printed materials. The standard generally assumes that the user is printing on commercial grade glossy paper.

SWOP-Uncoated: This standard is designed for use with the same ink sets but on uncoated paper.

Specifications for Non-Heatset Advertising Printing (SNAP): This standard is for newspaper printing using SWOP ink sets.

General Requirements for Applications in Commercial Offset Lithography (GRACoL): GRACoL describes the tools and standards for sheetfed and web offset developed by the International Digital Enterprise Alliance (IDEAlliance). It is designed to help print buyers, designers, and print specifiers work more effectively with print suppliers. GRACol-compliant ICC profiles are rapidly becoming the standard for digital proofing in North America. SWOP and IDEAlliance have formed an affiliation to address the coordinated development of specifications and guidelines, certification programs, software tools, educational seminars, and peer support networks

In addition, IDEAlliance has been instrumental in creating G7™, a documented and consistent methodology that allows printers to match multiple devices to each other for a consistent and predictable printed outcome. There will be a lot more on this later.

Japan Standard or DIC: This standard is characterized by different yellow tones than used by some of the other standards.This standard is outside the scope of this blog, or my expertise.

Eurostandard Ink Set: This standard is used by printers in Europe. Recently, research institutes such as FOGRA6 and industry associations such as bvdm7 have invested significant effort into colorimetric refinement of those standards, resulting in the Medien standard Druck and a series of FOGRA tolerances that clarify the European color standards. This standard is outside the scope of this blog, or my expertise.

----------

Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com