Measuring Differences in Appearance Follow

Do you see a difference in the two carpet samples above? The one on the left appears to be a darker pink while the one on the right seems lighter. These two pieces of carpet appear to be visually different. Would you believe that those two samples are exactly the same carpet, just viewed at a different angle?

How do you quantify the color difference between the samples at different viewing angles?  Appearance includes both the color of the object and the geometric light interaction of the sample.

These carpet samples were measured on the HunterLab LabScan XE, UltraScan PRO, and SpectraTrend HT instruments. Samples were measured at zero and one hundred eighty degrees to determine if the instrument could measure the appearance of the samples.

The LabScan XE and the UltraScan PRO were only able to discern small color differences between the two orientations of the sample. To obtain an accurate and repeatable measurement method for the carpet samples on the bench instruments the carpet had to be compressed thus eliminating the appearance difference.

The SpectraTrend HT instrument was able to discern large visual differences between the two sample orientations and was able to obtain a repeatable measurement method without having to compress the carpet fibers. This allowed the instrument to accurately measure the difference in appearance between the two sample orientations. The HunterLab SpectraTrend HT instrument works well for measuring difference in appearance of these carpet samples.