Other Considerations of ISO 3664:2009
Since the level of illumination can appreciably affect the appearance of an image,
the ISO 3664:2009 standard defines intensities of illumination. Two levels of
illumination intensity are specified: a high intensity level to be used for critical image
evaluation and comparison (allowing for full shadow illumination without washing out
highlight areas), and a lower level of illumination intensity which is used for more
practical evaluation of full tonal reproduction. It is assumed that the lower level of
illumination intensity provides lighting in which the average viewer is most
accustomed.
Maintaining uniformity of illumination throughout the plane of viewing is ensured
by the Standard as luminance measurements are required for at least nine evenly
spaced intervals across the viewing area.
Ambient light conditions can negatively influence precise color perception.
Therefore, ISO 3664:2009 considers multiple components of the viewing
environment in which reflective color and images displayed on color monitors are to
be evaluated. While the Standard does not define standardization of all components
of a viewing booth, it clearly specifies that the viewing environment conditions be
designed to minimize any outside interference with color observation. In addition to
controlling the color of the surroundings (including all surfaces of the viewing booth),
and eliminating extraneous ambient light, it is critical that certain best practice
geometries relating to the relative positions of the light source, the image, and the
observer be followed.6
Recommendations
It is recommended by color scientists, along with the graphics arts, photographic,
and color management communities, that the ISO 3664:2009 standard be fully
implemented industry wide. All color viewing stations should be equipped with ISO
3664:2009 compliant tubes. In order to prevent color miscommunication and
unnecessary metamerism issues, it is critical that all partners in the color
communication process, and throughout the entire color managed workflow, closely
follow the mandates of the Standard. Reference print specifications and
characterization data sets are in the process of being brought into compliance with
the ISO 3664:2009 viewing condition. Furthermore, the color measurement condition
M1, a specification of the newly revised color measurement standard ISO
13655:2009, provides a true D50 color illuminant/measurement condition which is in
alignment with the viewing conditions specified by ISO 3664:2009