THX Tech Pages

WHEREAS Lucasfilm, Ltd., through its Theatre Alignment Program ("TAP"), in cooperation with various members of the Distribution and Exhibition community, including the National Association of Theatre Owners ("NATO"), has promulgated certain goals for the operation of motion picture theatres, and

WHEREAS it is recognized by all parties that the criteria and standards which are part of these goals state the optimum conditions for the operation of motion picture theatres, and do not necessarily represent current standard operating conditions and practices, and

WHEREAS NATO has consistently and continuously advocated and promoted improving presentation quality and theatre performance by its members,

NOW THEREFOR BE IT RESOLVED that NATO hereby adopts the Proposed Criteria and Standards for Presentation Quality and Theatre Performance for Indoor Theatres (Revised March, 1989) as the goals its members should endeavor to achieve in the operation of their theatres.

(c) 1993 Lucasfilm Ltd. _TM TAP and Theatre Alignment Program are service marks of Lucasfilm Ltd. _TM

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Criteria
Presentation Quality and Theatre Performance
For Indoor Theatres

Purpose

At present, there are no comprehensive quidelines for the exhibition of motion pictures. Organization such as SMPTE, ASHRAE, and AES have created standards for specific technical aspects of presentation, but technical presentation is just a portion of the moviegoing experience. To assist the industry in standardizing the quality of motion picture presenatation and theatre performance, TAP is proposing the following standards for adoption by the industry

These standards are not being proposed for the purpose of evaluating theatres nor as a comdition for membership in NATO.

About The Standards

The standards are divided into three areas-Print Condition, Technical Aspect of Presentation (Viewing Conditions/ Image Quality and Sound Quality), and Theatre Maintenance Operations. They have been created with an emphasis on providing audiences with the best possible presentation quality and moviegoing experience.

The Standards state the optimum conditions in given categories and, therefore, represent goals. In some instances, the optimum has been compromised to accommodate the safety of patrons. In instances where standards may conflict state and/or local codes (such as zoning, building, fire, safety, and health codes), the codes should always take precedence and be adhered to.

The Standards

I. Print Condition
We should begin by re-iterating what seems fairly obvious to the engineers involved in film sound-track technology, what is frequently missed by some people involved in exhibition, and-is certainly misunderstood by much of the movie-going public -- the sound-track format, mono, Dolby Stereo, Dolby Stereo SR, and now the digital sound-track of Dolby SR•D, does not itself define how loud or quiet a sound-track will be, or how extended

Glossary of Terms Related To
Print Damage and Black Dirt Accumulation

a. None = No scratches, splices, or sound-track damage to date.
b. Very Minor = A scratch or a few scratches appearing for no more then a few seconds that are hardly noticeable and not distracting.

(c) 1993 Lucasfilm Ltd. _TM TAP and Theatre Alignment Program are service marks of Lucasfilm Ltd. _TM

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c. Minor = Scratches appearing for a few seconds that are only noticeable if looking for them specifically and not distracting. Splice(s) with no loss of visual or sound continuity. Sound-track damage present for a few seconds that is not distracting.
d. Notable = Scratches appearing for more than a few seconds that can be noticed by any viewer and are mildly distracting. Splice (s] with some loss of continuity. Sound-track damage present for more than a few seconds that is mildly distracting.
e. Significant = Continuous scratches that would more than likely be noticed by all viewers and are distracting. A large accumulation of mildly distracting scratches can also be significant. Splice(s) with substantial loss of continuity. Sound-track damage present for long durations that is distracting (usually to the point of necessitating a replacement for the damaged reels.)

Black Dirt Accumulation

a. None = No accumulation of dirt.
b. Very minor = A few black specks on the image appearing randomly. Hardly noticeable to the viewer.
c. Minor = Some accumulation of black specks on the image. Noticeable but not distracting to the viewer.
d. Notable = Moderate accumulation of black specks on the image. Noticeable and mildly distracting to the viewer.
e. Significant = Heavy accumulation of black specks on the image. Very noticeable and distracting to the viewer.

II. Technical Aspects of Presentation

Viewing Conditions and Image Quality:

1. Screen illumination

Screen luminance at the center of the screen should be 16 fL ⁺ /-2 fL. Screen luminance at the edges of the screen (5% in from each edge) should not be less than 75% and not more than 85% of that at the center. The distribution of screen illumination should be symmetrical about the geometiic center of the screen, and no portion of the illuminated area should be less than 10 fL.

Reference: American National Standard ANSI/SMPTE 196M-1986

2. Screen condition

Motion picture theatre screens should be free of rips, tears, discoloration, or other blemishes. Any seams in a screen, either vertical or horizontal, should not be obtrusive when an image is projected.

3. Reflected and Stray light on screen

Screen luminance of a blank screen (no projected image or light) when the theatre is operating normally Iauditorium lights set for presentation should be free of reflected and stray light. Reflected light on the screen may obscure image contrast. Room surfaces should not reflect significant light onto the screen. Surfaces of objects behind the screen should not reflect light onto the seating area.

Exit signs, regardless of placement, should not cast stray light on the screen [which may mean shielding signs where necessary). Doors should be arranged so that direct light from adjacent spaces or out-of-doors cannot shine directly on the screen.

Reference: Estes,"Effects of Stray Light," SMPTE journal

(c) 1993 Lucasfilm Ltd. _TM TAP and Theatre Alignment Program are service marks of Lucasfilm Ltd. _TM

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4. Light sources within field of view

The luminance of light sources within the field of view, such as exit signs or decorative lights, should not be distracting. It is recommended that exit signs be placed somewhere other than the wall where the screen is located. Where the placement and illumination of exit signs are mandated by state and local building and fire codes, one should adhere to the codes.

One should avoid placing shiny objects in places where they can reflect screen tight to the seating area. Glossy finishes should not be used in the front parts of the auditorium as they can cause glare.

5. Image focus

Resolution (focus) is the apparent sharpness determined by the ability of a system to reproduce a specified number of equally spaced black lines and white spaces in groups which are at right angles to each other. The following should apply:

Center resolution: greater than or equal to 68 lines/mm.
Side resolution: greater than or equal to 56 lineslmm.
Corner resolution: greater than 40 lines/mm.

This requirement applies to all formats, including those requiring use of anamorphic or other focal length adapters.

Reference: SMPTE EG 5-1982

6. Shutter ghost (image streaking)

Shutter ghost (travel ghost) is the streak or blur that occurs to an image resulting from any vertical motion of film in the gate as the projector shutter opens. With high contrast images, no shutter ghost should be visible on any part of the screen at any time.

7. Vertical (jump) and Horizontal unsteadiness (weave)

Jump is the vertical motion of the projected image. Weave is the horizontal motion of the projected image. The following should apply:

Jump : less than 0.20%
Weave : less than 0.25%

Reference: SMPTE RP 105-1981

8. Masking (condition, placement)

Theatres should have masking cloth or drapery, and it should be in good condition without rips or tears. If operable, it should adjust to at least the Flat (1.85:1) and the Scope (2.35:1) aspect ratios. Left and right side masking, when in place, should create parallel edges for the image. The top and bottom masking, when in place, should also create parallel edges for the image. Projected images should fill the screen and no blank screen surfaces should be visible.

If masking covers loudspeakers, the portion of the masking in front of the loudspeakers should be acoustically transparent. The edges of masking should be parallel and consistent with the correct projectable image dimensions.

(c) 1993 Lucasfilm Ltd. _TM TAP and Theatre Alignment Program are service marks of Lucasfilm Ltd. _TM

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