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ee —— eee ee ee eS oe ee eee ee ee SS ee a a ee | |,” eee ee eee a a a ee ee eee ee oe See Oe es Se eee, Se Pe, a en ee ee Federal Agencies Digitization Initiative Still Image Working Group — August 2010 Viewing Conditions A variety of factors will affect the appearance of images, whether displayed or printed on reflective, transmissive or emissive devices or media. Those factors that can be quantified must be controlled to assure proper representation of an image. We recommend following the guidance in the following standards- 2 [SO 3664 Viewing Conditions- For Graphic Technology and Photography Provides specifications governing viewing images on reflective and transmissive media, as well as images displayed on a computer monitor without direct comparison to any form of the originals. 2 [SO 12646 Graphic Technology — Displays for Colour Proofing — Characteristics and Viewing Conditions Provides specific requirements for monitors and their surrounds for direct comparison of images on a computer monitor with originals (known as soft proofing). NOTE: The following are common parameters controlled by users, however, refer to the standards for complete requirements and test methods. In particular, ISO 12646 specifies additional hardware requirements for monitors to ensure a reasonable quality level necessary for comparison to hardcopy. Monitor Settings, Light Boxes, and Viewing Booths We assume the assessment of many digital images will be made in comparison to the originals that have been digitized, therefore ISO 12646 should be followed where it supplements or differs from ISO 3664. We recommend digital images be viewed on a computer monitor set to 24 bits (millions of colors) or greater, and calibrated to a gamma of 2.2. TSO 12646 recommends the color temperature of the monitor also he set to SONNK (1150 illuminant) to match the white point of the illumination used for viewing the originals. Monitor luminance level must be at least 85 cd/m’, and should be 120 cd/m? or higher. The computer/monitor desktop should be set to a neutral gray background (avoid images, patterns, and/or strong colors), preferably no more than 10% of the maximum luminance of the screen. For viewing originals, we recommend using color correct light boxes or viewing booths that have a color temperature of 5000K (D50 illuminant), as specified in ISO 3664. ISO 3664 provides two luminance levels for viewing originals, ISO 12646 recommends using the lower levels (P2 and T2) when comparing to the image on screen. The actual illumination level on originals should be adjusted so the perceived brightness of white in the originals matches the brightness of white on the monitor. The Room The viewing environment should be painted/decorated a neutral, matte gray with a 60% reflectance or less to minimize flare and perceptual biases. Monitors should be positioned to avoid reflections and direct illumination on the screen. ISO 12646 requires the room illumination be less than 32 lux when measured anywhere between the monitor and the observer, and the light a color temperature of approximately 5000K. Practical Experience In practice, we have found a tolerable range of deviation from the measurements required in the ISO standards. When the ambient room lighting is kept below the limit set in ISO 12646, its color temperature can be lower than 5000K, as long as it is less than the monitor color temperature. To compensate for environments that may not meet the ISO standards, as well as difficulties comparing analog originals to images on a monitor, the color temperature may need to be set higher than SO0OK so that the range of grays from white to black appears neutral when viewed in the actual working environment. The higher color Technical Guidelines for Digitizing Cultural Heritage Materials: Creation of Raster Image Master Files 6