Stiles-Burch two-degree color mixture data

The 2 degree color mixture data of Stiles and Burch have been analyzed to study the differences between individual subjects and the lack of precision at the blue end of the spectrum. The luminous efficiency data have been compared to those of Judd's 1951 observer and the 1931 standard observer. The mixture data have been compared to those of Wright and Guild and have been related to mixture data of dichromats. One of the ten observers was found to have a luminous efficiency curve similar to that of a protanope and was excluded from the average data.