# Precise Color Communication

Even if two colors look the same to the human eye, as in the example of the two apples in Part I-11, slight differences may be found when the colors are measured with a colorimeter. In addition, the colorimeter expresses such differences exactly in numerical form. If for some reason the color of a product was wrong and the product was shipped without the problem being noticed, and the customer complained as a result.... The effect would not be limited to only the sales department or the production department, it would hurt the reputation of the entire company. Color control plays a very important role in preventing such problems from occurring.

 ∆E*ab=0.77 ∆L*=-0.32 ∆a*=-0.01 ∆b*=-0.70

 ∆E*ab=0.18 ∆L*=0.11 ∆a*=-0.06 ∆b*=0.13

 ∆E*ab=0.15 ∆L*=-0.08 ∆a*=-0.02 ∆b*=0.13
Let's look at how useful a colorimeter can be for color control.

Company A manufactures exterior plastic parts ordered by company B. Company B also orders similar parts from companies other than company A.
At company A, a full-time staff of inspectors is in charge of controlling color on the production line and visually evaluates products in comparison to color samples. Visual inspection depends on the eyes of skilled inspectors to determine whether or not a product is within the acceptance range as defined by the color samples. This work cannot be performed by anyone; it requires years of experience to develop an ability for visual inspection. As a result, the number of people who can do this work is limited. Also, the process can be performed only for a limited period of time per day or week, and the evaluation will vary according to the inspector's age and physical condition.
Sometimes, company B complained that the color of parts delivered by company A did not match those of other suppliers and so company B returned the parts to company A. Company A decided to utilize colorimeters for color control of its products on the production line. The colorimeters became very popular, because they were handheld and could be used even on the production line, they were easy enough for anyone to use, and measurements were quick so they could be used at any time.
Further, the data measured by the colorimeter were submitted with the products at the time of delivery as proof of the company's quality control.

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