To make substantial further improvement in color-rendering and brightness per watt of lamplight, we need to rid ourselves of the lumen and footcandle. Actions of the CIE, mentioned in the last installment, made this clear 40 years ago. So the luminous efficiency curve has to be replaced. The visual data comprising the 1931 2 degree CIE Standard Observer and that of the 1964 10 degree Observer will be the first two of the 14 sets of visual data from which we shall infer the form of the replacement-a new "perceived-brightness function."
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