ISO 3664 has long been the international standard that specifies viewing
conditions for critical color evaluation of images rendered on both reflective and
transmissive media; as well as for images displayed by color monitors. The ISO 3664
standard underwent its second revision in May 2009 with the intent of optimizing the
accuracy of critical color assessment. The revised standard, ISO 3664:2009, went
into effect internationally on January 1, 2012.1 ISO 3664:2009 addresses several
facets of the viewing condition including spectral characteristics of the illuminant,
intensity of illumination, uniformity of illumination, the physical conditions of the
viewing environment (including characteristics of the viewing surround and control
of ambient interference), and specifications for viewing geometry and the backing of
a viewed image.