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公开(公告)号：ZA746445B
公开(公告)日：1976-05-26
申请号：ZA746445
申请日：1974-10-09
Applicant: MOBIL OIL CORP
Abstract: In the selection of metallic paint pigments to color match a standard metallic paint coating, the tri-stimulus coordinates of the coating are measured at a plurality of different viewing angles with respect to the surface. A colorimeter has a rotating plaque holder. Incident light passes through blue, green or red filters. The light is reflected from the plaque and is detected by a photocell. By changing the angle of the plaque, tri-stimulus coordinates of the plaque are measured at different viewing angles. The total reflectance of the coating on the plaque is measured in a spectrophotometer. From the measured tri-stimulus coordinates and the measured total reflectance, the measured diffuse and angular reflectance of the coating on the plaque is obtained. A model which relates both the diffuse and the angular reflectance to the concentration of paint pigments is generated on an automatic data processor. Least square fitting between measured and predicted diffuse and angular reflectance is used. A formulation program generates the concentrations of pigments to be used in the initial batch. Thereafter, a shading program successively generates the changes in pigment concentrations which give the best least squares fit to the standard coating.
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