Disk Colorimetry; Including a Comparison of Methods for Computing Tristimulus Values for Certain Disks

This report provides a certain amount of information necessary for careful work with the disk method of colorimetry. Color temperatures are given for lamp and filter combinations of available instruments. Tristimulus specifications are given: for several Munsell papers under I. C. I. standard illuminants; for certain glossy papers under diffuse and 45° directional illumination; for colors made in the Munsell laboratory to match other colors when it was necessary to use different pigments; for several methods of computation, by summation for 5 and 10 mμ intervals, and by 10 and 30 selected ordinates; for curves differing slightly from each other; and for color differences significant in cotton grading. These last-mentioned figures are given as a basis for the comparison of the significance of all of the other differences.