Published On: 21/06/2002|Categories: 1998–2002, Vol.23 (2), Vol.23 (2002)|

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The NCS atlas was evaluated in two ways. The first provided a series of exhaustive colourimetric measurements (reproduced in the electronic appendix available in that were used for: (1) relating them to the descriptive parameters used by the atlas; and (2) analysing the general colourimetric properties of surface colours. The second type of evaluation examined the possibility of using the NCS atlas colourimetrically to specify colour tiles not belonging to it. The analysis of the relationship of the NCS with the colourimetric parameters showed that every NCS hue was associated with a specific chromatic angle and with one dominant wavelength. The relationships between NCS whiteness and CIE lightness, on the one hand, and between CIE and NCS chroma parameters, on the other, were high but not so closed. When the atlas was considered globally, it was observed that lightness strongly determined both the stimuli chromatic angle and CIE saturation. More specifically, for low lightness, the highest CIE saturations were observed for the chromatic angles associated with either of the spectrum extremes or with the purple line. For high lightness, on the contrary, the highest CIE saturation levels were observed for the chromatic angles related to the middle portion of the spectrum. The second type of NCS evaluation considered its possible utility for inferring the colourimetric parameters of samples not included in the atlas. A relatively low error level (∆ E < 8) was detected, so it was concluded that the NCS atlas can be used for those practical applications that require colourimetric computations with medium or low levels of precision.

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