Re: New SMPTE Standard Document For Viewing Environment Is Out
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I thought it would be of interest for serious videophiles in this calibration community to have a summary of SMPTE ST 2080-3:2017 ‘Reference Viewing Environment for Evaluation of HDTV Images.’ The actual standards document is copyright-protected so the full text is only available for purchase from SMPTE. A partial quote that offers the essence of the document’s value in understanding what it contains is from page 2:
“The creation of television images that are intended to follow a standard of consistency in reproduction requires definition of a reference display, of a controlled viewing environment, and of a set of measurement procedures to enable consistent calibration of both display and environment. This document specifies a controlled viewing environment referred to as the Reference Viewing Environment.”
Video professionals have long undertood that the viewing environment must be uniform in practice when mastering programs. This is due to the environment’s impact upon human visual perception. Consistent results in evaluating video images are dependent upon viewers working in standardized room conditions. Consumers who value image fidelity and authentic program reproduction in their home entertainment systems are served well by emulating professional best practices when designing and installing them.
The last time SMPTE published an official document for viewing environment best practices was back in 1995. At that time, NTSC CRT displays were the standard for both professional and consumer monitor use. A lot has changed since then.
A revision was desired to address the new ATSC HDTV standards, as well as significant advancements in monitor and television displays. Perhaps additional revisions can be expected for UHD/HDR/WCG programs and displays in the future. What we have in this recent revision includes some relatively minor changes. It also offers more detail regarding measurement parameters in setting up a reference viewing environment properly for HDTV and usage of more modern displays.
Here are a few particulars that deviate somewhat from the previous publication:
D65 ambient light level in the monitor environment surround “shall have” a luminance of 5.0 +/- 0.5 candellas per square meter (nits). This wording sets a formal standard, rather than the previous recommended practice of 10% of peak white displayed by the monitor. Coincidentally, the 5 nits surround illumination value specification aligns with recent statements by the ITU regarding usage for HDR mastering. The SMPTE document includes an interesting explanatory ‘Annex A’ describing the history, industry practice, and reasoning for this change in specification. A 5 nits value requires a spot photometer or spectroradiometer to measure. Previously, a 10% of peak white value could be approximated visually in the room with an appropriate test pattern displayed on the monitor screen.
The visual surround area extent (width and height) recommendation is no less than 90 degrees horizontal field of view and no less than 60 degrees vertical field of view.
The document suggests a reference monitor be placed in a free-standing environment 7 cm to 2.5 screen heights in front of the neutral gray wall providing the visual surround.
I recommend acquiring the entire document for anyone serious about image fidelity, display system design, installation, and calibration.
Best regards and beautiful pictures,
G. Alan Brown, President
SMPTE, THX, ISF, Lion AV Consultants
“Advancing the art and science of electronic imaging”