In free access online-calculations of Spot Colour Tone Value (SCTV) by ISO 20654:2017 can be done at: Perceptual Uniformity Tone Value calc • SCTV & CIE ΔE
Just copy the table with the Lab data by patterned and click "Calc".
Input data format:
Tone Value, Lab_L, Lab_a, Lab_b (split by tabs or...