AN ILLUMINANT LOCUS BASED ON NEUTRAL WHITES (PO04, 827-832)

Recently, different sets of research results have shown that the chromaticities for white perception were not located in the Planckian locus. The goal of the present study is to verify `neutral locus?. Sixty-one light stimuli having a luminance of 167 cd/m2 were used including 7 iso-CCT lines (6500K, 6000K,5000K, 4500K, 4000K, 3500K, 3000K) at 7-9 Duv levels (-0.025, -0.02, -0.015, -0.01, -0.005, 0, 0.005, 0.01, 0.015). Observers compared a pair of stimuli to judge which one appeared to be more `neutral?. Seventeen observers took part in the experiment. The results showed that the neutral whites are located between -0.010 to -0.015 Duv units below the Planckian locus. It was also found that the chromaticity close to 5900K appears to be the most neutral point on the newly established neutral white locus.