A colour-difference formula for assessing large colour differences

An experiment was carried out to study large colour differences. Two-hundre d-and-ninety-two wool pairs were prepared with an average difference of 12 CIELAB Delta E units. Visual assessments were conducted using gray scale an d pair comparison psychophysical methods by a panel of 20 observers. The re sults from the two psychophysical methods were used to test colour-differen ce formulae and compare their differences. The gray scale results were also used to compare with the other large colour-difference data sets, i.e., BF B, OSA, and WW. The present results together with part of the other data se ts were combined to form a single data set. A modified CIELAB colour-differ ence formula was developed having a structure similar to that of CIE94. It is named the GLAB colour-difference formula. (C) 1999 John Wiley & Sons, In c.