About the "Ideal Viewing Environment"
Viewing environment principles are discussed and demonstrated on Joe Kane Productions' 'Digital Video Essentials' DVD, in Title 2, Chapter 2, "Room Environment. Additional information can be found on Ovation Software's 'Avia Guide To Home Theater'. See: chapter 7, Home Theater Environment, Introduction and Background Lighting for Video, and select the "hot buttons" text boxes.
THE IMPORTANCE OF VIEWING ENVIRONMENT CONDITIONS IN A REFERENCE DISPLAY SYSTEM
The author’s purpose in this paper is to enlighten imaging industry professionals and home entertainment consumers in a seldom discussed and little understood dimension of optimum video display system design and installation. It’s the position of this paper that video is fundamentally a mass communication medium. The objective in such a medium is to convey an original message without loss, confusion, distortion or misunderstanding. Video relies upon images more so than words to carry its message. To convey more beautiful pictures is at the heart of the current HDTV revolution. This paper will focus more specifically upon home theater and the faithful reproduction of cinematic art via video displays.
Home cinema has developed into a major form of entertainment, enjoyment, escape, and relaxation for the contemporary consumer. The author recognizes an increasing interest in electronic image quality in our culture today. What follows is intended to better inform anyone curious about how to produce the most beautiful pictures in the home, which our current technology can provide. The practical keys that follow should serve as a guide in insuring that the costly electronic devices used in home entertainment systems will perform optimally, and communicate the art of cinema in the most faithful, beautiful and enjoyable way.
Electronic imaging is composed of both science and art. The science of imaging studies both the technologies involved and human perceptual factors. Any fully integrated and comprehensive approach to electronic display system design, installation, and calibration must take into account every component in the system. These components include: electronic device hardware, inter-connect cabling, program signals, room conditions, and last (but far from least) the viewer. A complete study and application of imaging science principles must encompass all of the above components. Ignoring any one of these can result in diminished total system performance. Diminished performance effectively reduces the value of the system.
The viewing environment is the least understood and, therefore, frequently ignored element in proper display system design, implementation and calibration. Viewing conditions always affect display performance, human perception of the image on the screen, and viewer comfort. A properly calibrated display will not be perceived correctly if there are conflicting viewing environment conditions.
The Society of Motion Picture and Television Engineers (SMPTE) is responsible for developing standards and practices for the motion imaging industries. Their recommended practices document, RP166-1995: ‘Critical Viewing Conditions For Evaluation Of Color Television Pictures,’ deals specifically with viewing room conditions and human perceptual factors in reference display environments. SMPTE’s human factors research found that viewing conditions profoundly affect the way video images appear and also impact viewing comfort. Their work applies to all forms of electronic displays and is beneficial for computer monitor use, digital graphics design, digital photography, electronic interactive games, technical, medical, industrial, security applications, home theater, etc.
Professional monitor environments (where critical image analysis is conducted for mastering video programs) use tightly controlled ambient lighting and neutral colored surfaces surrounding the display.
A CRT post-prodution monitor viewing environment (courtesy of Joe Kane Productions)
These room characteristics help preserve correct color perception and image fidelity. It is vital to consider that program post-production can involve multiple days, different technicians, and even various facilities working on the same project.
Such display industry standards are followed to insure unity, consistency, repeatability, quality, and faithfulness to the vision of the producer, all along the production and program delivery chain. In other words, image fidelity and artistic integrity are preserved as long as the rules of the system are followed. This is important for the consumer to understand, since the home entertainment system is the final link in the chain.
The International Telecommunications Union is another standards organization that recognizes the impact of viewing environment conditions upon a viewer’s perception of a display. Their Radiocommunication sector has published a recommended practice document in their Broadcast services (Television) series: ITU-R BT.710-4 "Subjective Assessment Methods For Image Quality In High-Definition Television." This document defines critical viewing conditions for the evaluation of HDTV images. It specifies environmental guidelines such as: horizontal viewing angel, color, orientation and brightness of ambient lighting, color of surrounding surfaces, etc.
Imaging excellence is the result of understanding the principles of imaging science, following display industry standards and practices, plus attention to detail when executing a display installation. Any reference display system design, installation and/or calibration service should include a disciplined attention to every element and component, if image fidelity and artistic integrity are worthy goals.
Residential viewing environments can be designed or retrofitted to emulate professional viewing conditions, thereby preserving image fidelity and viewing comfort. Here are some important elements and principles to consider:
FOR SELF-CONTAINED DISPLAY TYPES (direct view and rear projection TVs):
The following is from the Flat panel Display Laboratory at the National Institute of Standards and Technology (NIST): http://www.fpdl.nist.gov/tips.html
[AR = uses some anti-reflection coating or method]
A theoretical spectral power distribution (SPD) graph of CIE D65
An actual SPD graph of an Ideal-Lume Pro D65 bias light
An actual SPD graph of a typical household incandescent lamp
The preceding SPD graphs demonstrate how different the color spectrum can be between the lighting used in the reference viewing environments versus what is used in the average home. Residential lighing will skew or contaminate a viewer's perception of objects and images illuminated by them. Of particular note is the fact that home-type incandescent lighting is often electrically dimmed when TV programs are viewed. Dimmed incandescent lamps become even warmer in color temperature, which results in a spectral content that becomes even more red-dominant. Typical viewers will find color TV pictures look more natural when displayed in a room that uses ambient lighting with the same specturm as video white (CIE D65)
This is the test pattern from Joe Kane Productions’ ‘Digital Video Essentials.’
The TV’s picture controls should be set for dark room viewing, the test pattern is then displayed on the screen while observing the level of illumination on the wall behind the display.
The horizontal bar in the center of the gray gradient field is the same shade of gray all along
its length. As the background changes to a lighter shade, the bar appears to darken.
This image from the eChalk site was designed by Prof. R. Beau Lotto to illustrate how easily
influenced our color vision is. The center segment on both objects is exactly the same color.
A color analyzer would indicate that the segments are identical. Visually, they will
not look the same until a mask covers the surrounding colored areas.
FOR FRONT PROJECTION DISPLAY SYSTEMS:
An example of good front projection viewing environment design
An example of poor design, if image fidelity is paramount
Finally, these principles are recommended for achieving reference imaging and optimum viewing comfort. Residential viewing environments often present various compromises to ideal conditions. Simply keep in mind that the closer one can come to these imaging recommendations the better. The farther one deviates from these principles the more image fidelity and viewing comfort will be compromised.
Be advised that most home theater builders, architects, interior designers, and consumers do not understand imaging industry standards and recommended practices. Least understood are human perceptual factors and video viewing environment priciples as they affect system performance. Most systems depicted in magazines and that win awards are celebrated for how they appear with all the lights on, not for how they perform when the lights go out and the show begins. Uninformed preconceptions, opinions, fad, fashion, whim and impulse can result in serious consequences to system performance.
A viewer who values artistic integrity and image fidelity most will insist that the home theater or display system faithfully convey a video program as it was originally intended to be experienced. Viewing environment conditions play a vital and integral role in total system value, performance and audience experience.