ANSI IT10 7666-2002 pdf download Electronic Still Picture Imaging – Reference Output Medium Metric RGB Color Encoding: ROMM-RGB
The reference viewing environment shall be characterized by an “average” surround. This means that the area immediately surrounding the image border shall be assumed to be a uniform gray having the chromaticity values of CIE Standard lluminant Dao (Xa = 0.3457, Ya = 0.3585) and an observer adaptive luminance factor of 0.2 relative to the adapted white. The reference viewing environment shall be assumed to have a level of viewing flare that is 0.75% of the adapted white with the chromaticity values of CIE Standard lluminant Dan (Xa = 0.3457, yo = 0.3585). NOTE – If the actual output viewing environment differs significantly from that specified here, appropriate transformations may be necessary to determine the corresponding colorimetry that would produce the intended color appearance in the reference viewing environment. However, for actual viewing environments similar to the reference viewing environment, it should not be necessary to make such adjustments. The reference viewing environment was selected to make such adjustments unnecessary for many practical applications.
4.3 Reference Medium
4.3.1 Reference Medium White Point ROMM RGB shall be an encoding of the colors of an image on a reference medium having a reference medium white point with the chromaticity values of CIE Standard lluminant Dm (Xa = 0.3457, yo = 0.3585) and an observer adaptive luminance factor of Fw= 0.89 relative to the adapted white. Accordingly, the reference medium white point tristimulus values are Xw= FwXx= 85.81, Yw= Fw Ya = 89.00 and Zw= Fw Zn= 73.42, where X= 96.42. Ya = 100.00 and Zn= 82.49. These tristimulus values are based on the CIE 1931 Standard Colorimetric Observer defined in ISO/CIE 10527. NOTE – The observer adaptive luminance factor of 0.89 corresponds to a visual density of 0.0506.
4.3.2 Reference Medium Black Point The reference medium shall have a reference medium black point with the chromaticity values of CIE Standard lluminant Dan (Xn = 0.3457, Yn = 0.3585) and an observer adaptive luminance factor of Fx= 0.0030911 relative to the adapted white. Accordingly, the reference medium white point tristimulus values are Xx=FxXa=0.2980, Yq=Fx Yo= 0.3091 and Zz= Fe Zn= 0.2550. NOTE – The observer adaptive luminance factor of 0.0030911 corresponds to a visual density of 2 5099.
4.3.3 Reference Medium Primaries The chromaticity values for the ROMM RGB primaries shall be as given in Table 1, and equal amounts of the three primaries shall produce a neutral with the chromaticity values of CIE Standard lluminant Dao given in Table 1. All chromaticity values specified in this document shall be based on the CIE 1931 two- degree standard observer defined in ISO/CIE 10527. Rationale for the choice of these primaries is given in Annex A.