Description: For a given chromaticity (defined by xy coordinates), there is a maximum relative luminosity that is physically attainable. The relative luminosity is the percentage of light that an object colour reflects, measured with respect to the photopic luminous efficiency curve for the CIE standard observer. A colour attaining this maximum is called an optimal colour. Optimal colours depend on the illuminant chosen. This file lists optimal colours for illuminant C. Since illuminant C is the standardized illuminant for the Munsell system, an optimal illuminant C colour is at the boundary of the Munsell tree. Equivalently, these are colours of maximum chroma for a given hue and value. This list of optimal colours is taken from Table II of [MacAdam1935]. Two colours have been added, because they are helpful in calculations. These are theoretical black, given by xyY = (0,0,0), and pure white, given by xyY = (0.31006, 0.31616, 100). (0.31006, 0.31616) is the chromaticity of illuminant C. Theoretical black (an object colour of zero reflectance) does not attain maximum luminosity, but it is optimal in the sense that it is on the boundary of the Rosch colour solid. If converted to XYZ coordinates, it is also on the boundary of the CIE XYZ colour solid. [MacAdam1935] David MacAdam. "Maximum Visual Efficiency of Colored Materials," JOSA, Vol. 25, pp. 361-367, November 1935. DESCRIPTION ENDS HERE x y Y 0.0000 0.0000 0 0.1363 0.0692 10 0.1308 0.0792 10 0.0808 0.2132 10 0.0371 0.4135 10 0.0251 0.5007 10 0.0181 0.5893 10 0.0181 0.6718 10 0.0276 0.7416 10 0.0434 0.7890 10 0.0687 0.8178 10 0.0996 0.8252 10 0.7040 0.2946 10 0.5126 0.1913 10 0.3424 0.1028 10 0.2813 0.0771 10 0.2518 0.0693 10 0.2378 0.0674 10 0.2230 0.0663 10 0.1868 0.0664 10 0.1628 0.0676 10 0.1289 0.1268 20 0.1230 0.1438 20 0.1027 0.2152 20 0.0762 0.3420 20 0.0572 0.4775 20 0.0500 0.6250 20 0.0637 0.7410 20 0.0787 0.7747 20 0.0992 0.7975 20 0.1239 0.8055 20 0.1518 0.7983 20 0.6717 0.3273 20 0.5542 0.2513 20 0.4077 0.1603 20 0.3463 0.1263 20 0.3195 0.1150 20 0.3075 0.1122 20 0.2968 0.1104 20 0.2586 0.1104 20 0.1918 0.1182 20 0.1302 0.1764 30 0.1255 0.1980 30 0.1092 0.2845 30 0.0909 0.4178 30 0.0855 0.5500 30 0.0836 0.6110 30 0.0911 0.6700 30 0.0975 0.7140 30 0.1100 0.7487 30 0.1294 0.7700 30 0.1462 0.7806 30 0.1698 0.7793 30 0.1957 0.7696 30 0.6390 0.3613 30 0.5530 0.2950 30 0.4300 0.2040 30 0.3733 0.1658 30 0.3485 0.1528 30 0.3300 0.1462 30 0.3140 0.1443 30 0.3045 0.1447 30 0.2643 0.1503 30 0.1383 0.2180 40 0.1350 0.2425 40 0.1246 0.3363 40 0.1179 0.4720 40 0.1343 0.6800 40 0.1596 0.7377 40 0.1766 0.7470 40 0.1952 0.7500 40 0.2437 0.7305 40 0.2964 0.6903 40 0.3200 0.6357 40 0.6065 0.3925 40 0.5395 0.3320 40 0.4347 0.2410 40 0.3833 0.2000 40 0.3607 0.1851 40 0.3527 0.1807 40 0.3453 0.1777 40 0.3325 0.1752 40 0.3260 0.1750 40 0.3003 0.1783 40 0.2727 0.1844 40 0.2276 0.1955 40 0.1510 0.2520 50 0.1497 0.2785 50 0.1462 0.3736 50 0.1490 0.5017 50 0.1589 0.5990 50 0.1677 0.6411 50 0.1782 0.6750 50 0.1913 0.6980 50 0.2222 0.7185 50 0.2867 0.6936 50 0.3412 0.6493 50 0.4066 0.5890 50 0.5759 0.4231 50 0.5207 0.3655 50 0.4304 0.2737 50 0.3844 0.2309 50 0.3489 0.2071 50 0.3347 0.2026 50 0.3175 0.2046 50 0.3000 0.2092 50 0.2746 0.2162 50 0.2024 0.2373 50 0.1694 0.2797 60 0.1698 0.3065 60 0.1732 0.3995 60 0.1847 0.5156 60 0.2011 0.5982 60 0.2117 0.6316 60 0.2238 0.6567 60 0.2525 0.6823 60 0.2694 0.6840 60 0.3344 0.6502 60 0.3908 0.6016 60 0.4605 0.5364 60 0.5470 0.4514 60 0.5004 0.3963 60 0.4217 0.3042 60 0.3803 0.2593 60 0.3500 0.2330 60 0.3376 0.2284 60 0.3238 0.2294 60 0.3132 0.2322 60 0.2593 0.2497 60 0.1932 0.3005 70 0.1953 0.3263 70 0.2064 0.4136 70 0.2261 0.5163 70 0.2495 0.5835 70 0.2733 0.6282 70 0.3063 0.6432 70 0.3213 0.6415 70 0.3408 0.6316 70 0.3876 0.5999 70 0.5187 0.4780 70 0.4795 0.4243 70 0.4107 0.3319 70 0.3566 0.2675 70 0.3460 0.2578 70 0.3356 0.2525 70 0.3185 0.2544 70 0.2875 0.2651 70 0.2290 0.2868 70 0.2236 0.3120 80 0.2282 0.3382 80 0.2465 0.4183 80 0.2743 0.5056 80 0.2991 0.5591 80 0.3136 0.5784 80 0.3284 0.5913 80 0.3570 0.5932 80 0.3785 0.5912 80 0.4493 0.5433 80 0.4901 0.5038 80 0.4562 0.4505 80 0.3966 0.3584 80 0.3631 0.3103 80 0.3391 0.2815 80 0.3304 0.2754 80 0.3229 0.2756 80 0.3035 0.2802 80 0.2747 0.2926 80 0.2276 0.3119 80 0.2631 0.3192 90 0.2697 0.3410 90 0.2956 0.4111 90 0.3302 0.4827 90 0.3590 0.5232 90 0.3742 0.5364 90 0.3896 0.5438 90 0.4020 0.5493 90 0.4221 0.5430 90 0.4397 0.5350 90 0.4555 0.5235 90 0.4295 0.4741 90 0.3330 0.3080 90 0.3230 0.2975 90 0.3180 0.2958 90 0.2980 0.3030 90 0.2813 0.3106 90 0.2857 0.3185 95 0.2943 0.3395 95 0.3226 0.4055 95 0.3608 0.4679 95 0.3907 0.5025 95 0.4055 0.5126 95 0.4209 0.5180 95 0.4300 0.5195 95 0.4070 0.4720 95 0.3630 0.3855 95 0.3270 0.3172 95 0.3160 0.3069 95 0.3053 0.3096 95 0.31006 0.31616 100