Topic header: Uniformity measurement for projection and direct view display
Keywords: Movie projection systems; Movie direct view displays; standard; Uniformity measure;
Practical standard paper
This paper is about a practical uniformity measurement defined for a national standard.
French cinema theaters are following strict rules; there are two standards involved when according theater operation license. One standard is about architectural considerations, the other about movie reproduction parameters. The main goal of these specifications is to ensure that movies are reproduced uniformly in all theaters while matching the intention of the creative team during final check. Another goal is to allow a satisfying perception by the audience, trying to avoid unnecessary physical or audio-visual stress.
These two standards are currently under periodic revision. The specifications listed in the standard about movie reproduction is including uniformity formula.
The validity of this uniformity formula was questioned by some counterexamples. A new uniformity measurement is under study.
The proposed method is unifying projection and display systems in the same measurement. Projection vignetting effect is cancelled using current room and screen dimensions. The formula is also independent of the reproduction system dynamic range.
Nine locations on screen are used as points of measurement.
The proposed measurement of uniformity is based on the statistical measurement called the K-L distance. It is comparing current results with a standard statistical distribution. The type of distribution is chosen based on practical consideration.
Calculations are simple enough and are implemented in a spreadsheet
1. The vignetting effect, inherent to projection systems, is cancelled using a simple approximation, giving the same valid measurement for projection and direct view display.
2. The distribution of measurement values, eventually corrected, is compared to a standard distribution, giving a single estimator, i.e. the K-L distance. For practical reasons, nine locations are chosen on screen.
3. Uniformity estimator value is used to categorize the actual reproduction in few quality classes. The complementary maximum luminance deviation value is used normatively to accept or reject the current room performance.