Abstract: Color matching experiments were carried out with 2 observers on 3 colortemperature points, i. e. ∞K, 8333K and 4167K, on the Planckian locus inthe CIF: 1960 Diagram. A 2°bi-partite field on a visual colorimeter wasused for matching the above standard lights with test lights. The 2 observersgave similar results in that: 1) The size and shape of the tolerance areasfor a match are different for the 3 color temperature points; 2) The highcolor temperature points of ∞K and 8333K are not situated at the centerof the tolerance areas, which indicates that these areas on the Planckianlocus of the CIE 1960 UCS Diagram may not be uniform. But the colortemperature point of 4167K is at the center of the tolerance area whichshows that the area around this point is more uniform.

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