Just in case you ever feel the need to calculate the dE of a proofing substrate used for Fogra 39L (iso coated V2). The simple formula below can be used.!
See – Science and art can work together.
The dE can be calculated from dL*, da* & db* as it is the square root of the sum of the squares odd L*, da* & db*. The formula below shows how.
, two colors in L*a*b*: