ISO 20654:2017 Preview
Graphic technology -- Measurement and calculation of spot colour tone value
ISO 20654:2017 defines a metric for assessing intermediate tones of a spot ink. This method for the calculation of Spot Colour Tone Value (SCTV) produces approximately uniform visual spacing of tones between substrate and solid. It can be calculated from spectral reflectance or colorimetric measurements of the solid ink, substrate and one or more patches of intermediate tones to be measured.