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Topic: AMC replacing MPX units?
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Ken Lackner
Phenomenal Film Handler
Posts: 1907
From: Atlanta, GA, USA
Registered: Sep 2001
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posted 03-07-2009 05:40 PM
Julio,
I recall hearing that each projector is projecting the identical image, and they are overlaid on one another, thus increasing brightness and contrast, but not resolution. Now perhaps the person who told me this was misinformed, but this is how I understand it to be. I do know that if one projector goes down, you can still run with only the remaining projector, which I don't think would be possible if they each projected a different image; you'd loose half your pixels, whereas this way at least you only loose half the brightness.
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 03-08-2009 07:03 AM
As I said, look at Imax patents. They all state what we've been saying here: i.e. methods to make 2K projecting arrays "almost look like 4K".
Just a random example:
quote:
Apparatus and techniques for enhancing characteristics of electronic projection systems are detailed. Included among the techniques are both superimposition of sub-images and tiling of superimposed images, the combination of which can be advantageous in improving resolution of projected images. Pre-modulators and polarizing beam splitters also may be used as parts of the innovative systems.
Etc
quote:
U.S. Pat. No. 5,386,253 to Fielding, incorporated herein in its entirety by this reference, discusses exemplary projection systems utilizing one or more spatial light modulators (SLMs). As noted in the Fielding patent: Spatial light modulatordevices include so-called "active matrix" devices, comprising an array of light modulating elements, or "light valves," each of which is controllable by a control signal (usually an electrical signal) to controllably reflect or transmit light inaccordance with the control signal A liquid crystal array is one example of an active matrix device; another example is the deformable mirror device (DMD) developed by Texas Instruments . . . See Fielding, col. 1, II. 13 21. Of course, yet othertypes of light "engines," or sources, exist, and various of them may be used in connection with the inventions described herein.
Regardless of the type of light sources and modulators used, audiences frequently desire to see images high in detail and richness and low in objectionable artifacts. High resolution and image quality in particular facilitates suspension ofdisbelief of an audience as to the reality of the projected images Such quality indeed often is an important factor in the overall success of the motion picture viewing experience among today's audiences.
Producing these high-resolution images is not without added cost, however. Imax Corporation, for example, the intended assignee of this application, utilizes not only specialized cameras and projectors, but also seventy millimeter, fifteenperforation film to increase the resolution and quality of projected images. Conventional electronic projectors (and especially these utilizing SLMs), by contrast generally cannot supply equivalent resolution in projected images. As well suchelectronic projectors frequently fail to furnish the dynamic range and overall brightness of images provided by large-format films. They nonetheless may desirably (or necessarily) be employed to display non-film-based images such as (but not limited to)computer-generated graphics or material captured with electronic cameras.
U.S. Pat. No. 5,490,009 to Venkateswar, et al., also incorporated herein in its entirety by this reference, details techniques purporting to enhance image resolution in systems employing multiple SLMs. According to the Venkateswar patent,sub-images generated by different SLMs are simultaneously displayed such that some sub-images are spatially offset horizontally or vertically from others. This results in partial superposition of the sub-images, with the offset supposedly allowing atwo-SLM system (with each SLM having "x" pixels per row) to provide "a perceived quality approaching that of a system that generates a single image from an SLM having 2(x) pixels per row." See Venkateswar, col. 2. II. 41 43.
U.S. Pat. No. 5,612,753 to Poradish, et al., additionally incorporated herein in its entirety by this reference, discloses alternative techniques for, purportedly, increasing brightness of projected images or extending the projected number ofgray levels. FIG. 1 of the Poradish patent illustrates a projection system in which light from two sources is reflected toward separate lens systems and then focused separately on distinct color wheels. Light from each color wheel thereafter isreflected to an SLM (preferably a DMD) via a total internal reflection (TIR) prism, with each SLM modulating the light and directing it back to the associated TIR prism. As directed, the light is then transmitted by the prisms to lenses for projectiononto a screen. See Poradish, col 3, II. 6 39. In essence, therefore, the Poradish patent contemplates use of dual DMDs present in parallel paths existing from separate light sources to a screen.
While the techniques of the Venkateswar and Poradish patents arguably might enhance the resolution of an image produced by a digital projector, alone either is unlikely to provide resolution consistent with that of large-format film. Enhancedresolution of images produced by digital projection systems thus remains a significant issue for those engaged in development of commercial projection equipment. Absent further advancement in this area, viewing of electronically projected images remainless satisfying to public audiences.
SUMMARY OF THE INVENTION
The present invention seek to provide such advancements by addressing differences of, typically (but not necessarily exclusively electronic. SLM-employing projectors. It further does so in a more comprehensive manner than heretofore considered,attempting to create equipment and techniques capable of providing images of sufficient overall quality that they may be used in venues instead of, or in addition to, traditional large-format film projectors without disturbing audience perception thatthe viewed images are of high quality. As noted above, this perception is a significant aspect of modern-day viewing experiences, at times helping determine overall success among the public of particular motion pictures.
Embodiments of the present invention utilize not only superimposition, but also tiling to effect improvements to resolution of digitally projected images. "Tiling" describes the concept of joining two or more groups of images (or "sub-images")edge to edge, with each sub-image containing only a fraction of the total projected image. Because each sub-image conveys only a fraction of the overall image, its resolution will be greater than if the sub-image conveyed the total image itself.
Again, I don't know exactly what Imax is doing, but most people in the industry are talking like they knew it was a pixel shift from 4K. You "lose" half the pixels, but you start out with twice as much as 2K, so you are back to the max a 2K system can do anyway.
But it's a 2K "supersampled" and thus less objetable aliasing above nyquist, improving the overall MTF. The bandpass filter for 4K can be twice as large as for 2K.
Again, don't know what they are doing or how they are doing it, but a pixel-shift of sorts from a 4K DCI master into 2x2K projectors would make sense to me, as would projecting the two images at slightly different illumination floors as to slightly improve perceived contrast.
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