Optics: motion pictures – With framing and/or travel ghost elimination
Reexamination Certificate
2000-01-12
2002-09-17
Adams, Russell (Department: 2851)
Optics: motion pictures
With framing and/or travel ghost elimination
C352S092000, C352S162000, C352S221000, C352S229000
Reexamination Certificate
active
06450644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to motion picture film registration techniques and, more particularly, to a system and method for correctly registering frames of motion picture film during the projection process to provide enhanced resolution of the projected images.
2. Description of the Related Art
Film projectors and the motion pictures they project have amazed and delighted audiences around the world for over a century. However, the term “motion pictures” is really a description of an illusion, for the pictures do not actually move at all. To the contrary, still images, typically 24 per second, must be projected in as static a manner as possible. This is not a simple proposition given the fact that in one minute 1,440 images or “pictures” are presented to the viewer. The illusion of motion is created by the differences between succeeding still images and is dependent upon the precise positioning or “registration” of these images with respect to an aperture in the projector.
One of the problems associated with existing motion picture film projectors occurs when succeeding images are positioned in slightly different locations in the projector's aperture. When this happens, a given point on those images will appear to be blurred, even if individual images show that point to be perfectly sharp. Of course, individual images in motion pictures are not viewed separately, but, rather, over time in rapid succession.
In the context of motion picture technology, the word “register” (the root for “registration”) is not formally defined. Perhaps the closest applicable general definition is provided in the
Random House Dictionary Of The English Language,
Second Edition Unabridged (1983): “(11b) Print. Correct relation or exact superimposition, as of colors in color printing.” In the art of motion pictures, however, “registration” has a slightly different meaning. Motion picture photographic “registration” means the repeated placement of each image, one after another, in as precise a manner as possible throughout the entire chain that comprises the system of cinema imaging. As described below, there are several steps in this chain, starting with creation of the image and ending with its projection.
At the outset, film is moved through the camera intermittently and positioned by “registration pins” in precisely the same place, called the “aperture”. In this way, a succession of areas called “frames” are exposed to light, thus creating “latent images” that become a visible image after development. Because the “frame” defines the rectangular space on the film that is occupied by the “image,” the terms “frame” and “image” shall be used interchangeably and synonymously with each other herein.
During editing and other post-production processes, images created in the camera are modified when appropriate. Then they are duplicated for distribution through a process that involves intermediate steps. These intermediate steps include contact printing of an inter-positive (“IP”), and using that IP to make inter-negatives (“IN”).
In the next step, the IN is transferred onto release print film via high-speed contact printing, which is an unregistered process that operates at up to 17×-play speed, or faster. The “release prints” made by this process are distributed to theaters for projection. When the release prints are projected, the frames are intermittently positioned in a fixed position relative to the “aperture” of a projector's “gate.” Light from a lamphouse in the projector projects the images onto a screen for viewing by an audience.
Registration is not a factor in creating high resolution still photographic images. The photographer and viewer of a still photograph are concerned only with a single image recorded and printed from a single piece of film containing that image. However, registration is a crucial component required for high resolution imaging in motion pictures. As noted above, motion pictures are dependent on thousands of images seen one after another in rapid succession. Thus, in motion pictures, the collective impression of resolution or sharpness is highly dependent upon the repeatable, accurate positioning in the projector of every image that is photographed and projected.
“Resolution” is another term for sharpness or clarity. In motion pictures, resolution is a function of several factors, which include: (1) lens sharpness; (2) film negative granularity; (3) repeatable, accurate registration of the film in the camera's aperture; (4) repeatable, accurate registration during exposure of film IP's, IN's, and release prints; (5) film print granularity; and (6) repeatable, accurate registration of the release print in the projector. Of all these factors, nos. 4 and 6 are the most severely flawed in current motion picture technology. According, a long-felt need has existed for a system and method that can address these factors and thereby provide more precise registration and enhanced resolution across the entire system of motion picture imaging.
The final measurement of motion picture resolution must be made by analysis of a projected image at 24 frames per second (standard) or faster, not by inspection of individual frames as with still photography. Ideally, the registration precision of the projector should match that of the camera. Unfortunately, that is not now and never has been the case. As noted above, motion pictures cameras use highly precise, mechanically activated “registration pins” to achieve and maintain final and repeatable film positioning from frame to frame. On the other hand, theatrical projectors use registration techniques that are, at best, considerably inaccurate about both the longitudinal and lateral axes. This inaccuracy gets progressively worse as various mechanical parts in the projector's intermittent movement and gate are subjected to normal wear over time. But the primary cause of this inaccuracy is the 100-year-old design of the projector movement itself. Projector gates, intermittent sprockets, and the “Geneva” mechanism that turns these sprockets in a pause-then-rotate cadence have failed to evolve in any meaningful manner.
As described more fully below, projector registration in its present state is primarily achieved by means of the friction provided by spring tension in the projector gate, acting against the film, which is advanced by the rotational movement of the intermittent sprocket. This intermittent sprocket is typically positioned about 2 to 4 inches or more below the aperture and pulls the film through the gate. When the intermittent sprocket stops pulling the film, the spring tension in the gate acts on the film sandwiched within it and friction causes the film to stop. But this is a highly passive design that lends itself to imprecision. For example, gate friction varies due to adjustable spring tension. Moreover, the film print itself exhibits variable “slickness” due to waxing, wear and other environmental factors. Therefore, each succeeding frame simply cannot be registered in the exact same location as the preceding frame.
During projection, inaccurate longitudinal registration of the film produces an up and down film movement called “jitter,” while inaccurate lateral registration produces a side-to-side film movement called “weave.” Both jitter and weave are greatly magnified by the extreme enlargement of projection. At a minimum, jitter and weave in any noticeable amount will result in a softening and blurring of detail and impair the resolution of the projected images.
The use of larger images on film, as with the various 70 mm formats, creates a sharper image on screen simply because less enlargement is required to fill the screen. Consequently, the jitter and weave of the image is less noticeable with 70 mm release prints. However, the higher cost and the lack of 70 mm projectors in most theaters renders the various 70 mm formats moot as an option, except in a few “special venue” theaters. Indeed, if jitter and weave in the 70 m
Behrns Don P.
Goodhill Dean K.
Safreno Ty
Adams Russell
Fuller Rodney
Knobbe Martens Olson & Bear LLP
Maxivision Cinema Technology
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