Several efforts have been made in the past to use photocells for direct color measurements. Fast spectrophotometers were designed, and one instrument displayed the spectral response, for all practical purposes, instantaneously. These instruments facilitated the accumulation of the basic data considerably; however, they left considerable computational work to be done in establishing the visual effect of the measured color.
In order to avoid the tedious job of product integration involved in obtaining the ICI coordinates, it was proposed to construct an instrument with a certain photocell-filter combination approximating the ICI standard distribution factors. However, the extent of approximation is limited particularly for the curve with its double components.
The new instrument provides a good approximation of the ICI coordinates by means of a novel unidirectional cross-feed arrangement, which injects a portion of the response into the response circuit. Three integrated signals can be read on three meters simultaneously, and the ICI coordinates can be computed by one addition and two dividing operations.
© 1951 Optical Society of AmericaFull Article | PDF Article
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