The Effective Gain of a Projection Screen in an Auditorium

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Publisher: SMPTE — White Plains, NY, USA
Doc Type: Journal Article
Content Type: Original Research
Abbreviated Title: SMPTE Mot. Imag. J
Volume: 119, No. 7, pp. 62–67
Abstract: A gain screen is a technology used to increase the light levels seen by the audience without increasing the output of the projector. The quoted gain of the screen is the location of the highest gain, which is available at a single location on the screen (the hot spot), and for a limited number of seat locations near the center aisles. However, the perceived brightness of the image on the screen is not solely determined by the peak brightness of the hot spot, nor is the seat in the center of the auditorium the only location with an audience member. The perceived brightness, a subjective quantity, is more closely related to the total amount of light reflecting from the screen to the viewer than to the single hot spot point. Objectively, what we really want to know is the Lumen value at the viewer's location, rather than the foot-Lambert value of a single point on the screen. Measuring the gain of the screen at many locations in the theater is not practical, but fortunately the information to calculate the gain at each seat exists in the screen specification sheets, and the room geometry. Once the screen gain is calculated for each seat in the auditorium, the overall effective screen gain can be determined from their average. A method is demonstrated for calculating this average screen gain and the overall effective room light level. The gain averaged over the screen and over all seats in the auditorium is always lower than the quoted gain of the screen. For 3D systems using silver screens, the average left eye/right eye crosstalk across the screen is negatively impacted by the screen doing an imperfect job of maintaining polarization, especially at the edges of the auditorium. Larger values of crosstalk are coincident with poor performance from both a gain and uniformity standpoint.
Publication Date: 2010-10-01
DOI: 10.5594/J17316
ISSN: Print: 1545-0279 | Electronic: 2160-2492
Link: https://doi.org/10.5594/J17316
Author(s): Martin RichardsDolby Laboratories, Imaging group of the Products and Technologies department.
bio
Martin J. Richards is a principal member of the technical staff at Dolby Laboratories where he works in the imaging group of the Products and Technologies department. During his 24-year career at Dolby, he has been involved in the design of a number of products, including Dolby Digital sound on film, Dolby D-Cinema, and Dolby 3D. In 2007, Richards received an AMPAS Sci/Tech Award of Commendation for conversion of film to Cyan dye tracks. Richards holds 12 US patents on a variety of subjects, from electronics to optics. Before Dolby, he worked at Ampex Corp. in the optical signal processing section of the R&D department, and in the data systems group, where he worked on high-density optical and magnetic recorders.
Dave SchnuelleDolby Laboratories, Imaging group of the Products and Technologies department.
bio
Dave Schnuelle represents Dolby Laboratories as senior director, image technology, and is responsible for guidance in Dolby's efforts in the television, cinema, and consumer imaging areas. He began his career in 1969 as an engineer on television outside broadcasts while attending Purdue University. Working with Lucasfilm's THX Division, beginning in 1991, Schnuelle was responsible for founding the THX Digital Mastering Program for quality assurance of home video masters and duplicated software. As director of technology for THX, he directed research efforts into new technology for cinemas.
Copyright: © 2010 Society of Motion Picture and Television Engineers, Inc.

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Martin Richards and Dave Schnuelle; The Effective Gain of a Projection Screen in an Auditorium, SMPTE Motion Imaging Journal ( Volume: 119, Issue: 7, October 2010); SMPTE, 2010. Available at https://doi.org/10.5594/J17316

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Martin Richards and Dave Schnuelle; The Effective Gain of a Projection Screen in an Auditorium, SMPTE Motion Imaging Journal ( Volume: 119, Issue: 7, October 2010); SMPTE, 2010. Available at https://doi.org/10.5594/J17316

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<span class="citation">Martin Richards and Dave Schnuelle; <cite>The Effective Gain of a Projection Screen in an Auditorium</cite>, SMPTE Motion Imaging Journal ( Volume: 119, Issue: 7, October 2010); SMPTE, 2010. Available at <a href="https://doi.org/10.5594/J17316" target="_blank" rel="noopener">https://doi.org/10.5594/J17316</a></span>

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Martin Richards and Dave Schnuelle; The Effective Gain of a Projection Screen in an Auditorium, SMPTE Motion Imaging Journal ( Volume: 119, Issue: 7, October 2010); SMPTE, 2010
doi: 10.5594/J17316
url: https://doi.org/10.5594/J17316

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Martin Richards and Dave Schnuelle; <cite id="bib-10-5594-j17316">The Effective Gain of a Projection Screen in an Auditorium</cite>, SMPTE Motion Imaging Journal ( Volume: 119, Issue: 7, October 2010); SMPTE, 2010
<span class="doi">10.5594/J17316</span>
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