1964 CIE Supplementary Observer Applied to the Colorimetry of Rutile and Anatase Forms of Titanium Dioxide

Abstract

The study by White and Jacobsen of the applicability of the 1964 CIE supplementary observer to large-field colorimetry of the rutile and anatase crystal forms of titanium dioxide has been repeated. The six painted panels used by them were remeasured on a Hardy-type spectrophotometer with closely agreeing results. The arrangement of the panels in order of whiteness by north-sky light was made by 24 observers, yielding 45 arrangements, and these too were in good inverse agreement with the 26 yellowness arrangements made by 13 observers by White and Jacobsen. The spectrophotometric data were reduced to values of U*, V*, W* of the 1964 CIE uniform color space, and the sizes of the chromaticity differences between each panel and the magnesium oxide whiteness standard were computed. By substituting, for CIE illuminant C, the newly recommended CIE illuminants D6500 and D25000, representative of overcast sky and clear sky, respectively, and by taking account of normal variations of amount of lens pigment from one observer to another, we found that the 1964 CIE supplementary observer yields correct predictions of the frequency of the various whiteness arrangements of the six panels.