BFD (l:c) Colour-difference Formula Part 1 – Development of the Formula

A new colour-difference formula, BFD(l:c), has been developed using the combined experimental results relating to small colour differences between pairs of surface colours. Various aspects of colour differences have been considered in turn to decide the form of the formula required, and the constants in the formula have been optimised using the combined perceptibility and acceptability results. The new formula is similar in structure to the CMC(l:c) formula in most respects. However, it was found that a new term was required to take account of the fact that when chromaticity discrimination ellipses calculated from experimental results are plotted in a*b* space, they do not all point towards the neutral point