Copyright © 2019 Apple Inc.

The files in this folder consist of HDR10 D65 in BT.2020 white-point patches of varying intensities. 

The theoretical (ideal) luminance values are:

10-bit Codeword   cd/m^2	
64                0.0000	
108               0.0606	
152               0.3285	
196               1.0146	
240               2.4653	
284               5.2375	
328               10.2138	
372               18.7807	
416               33.1037	
460               56.5543	
504               94.3784	
544               148.0345
588               239.8111
632               384.7139
676               613.0797
720               973.1321
764               1542.2137
808               2445.6735
852               3889.1351
896               6214.6101
940               10000.000

The ideal CIE 1931 x,y values are the same for all luminance points.

x: 0.3127
y: 0.3290

For a 1000-nit capable display, the luminance values will track closely to the ideal values up to 1000-nits and then clamp any higher value to 1000.