International color-reproduction standards allow printers to compete globally, increase productivity, and make more money. This article digs into the foundations of standards and highlights the value of conforming to them.
By Mike Ruff
With the knowledge of the color spectrum, Albert Munsell developed a natural-color-recognition system called the Munsell Color System. He brought order to color when he developed the first numerical scheme for color designation. This was the foundation for color science. He was the first person to present a practical color-order system by which an individual could specify color-by-the-numbers (Figure 3).
Using Munsell’s system made it possible to discuss color scientifically. He defined color in terms of hue, value, and chroma. Hue was defined as the actual color—red, blue, green, etc. Value was defined as the color’s lightness or darkness. Chroma was defined as the color’s strength. He published an atlas that defined the Munsell Color Standard, and his work was embraced by the scientific community. In 1914, Munsell was invited to present his findings to the scientific communities of England, France, and Germany. His theory is still taught today.
In 1931, the Commission Internationale de l’ E’clairage (CIE) characterized the visual response of the human eye. The mapping of XYZ, based on the experiments conducted by W. David Wright and John Guild in the CIE RGB color space, was born (Figure 4). Then, in 1945, Richard Hunter, while working for the National Bureau of Standards, created a new tri-stimulus color model called
L*a*b*. He scaled color space in an effort to achieve near-uniform spacing of perceived colors (Figure 5). One of the biggest benefits of this uniform spacing was that color tolerancing was now numerically possible. The term Delta E, designated by the Greek symbol ΔE, came into existence. Delta E was used to characterize total color difference—exactly what manufacturers of color-critical products and their designers, printers, and clients needed (Table 1). This ushered in the era of international standards of color output.
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