Facsimile and static presentation processing – Static presentation processing – Communication
Reexamination Certificate
2001-08-23
2004-08-17
Wallerson, Mark (Department: 2626)
Facsimile and static presentation processing
Static presentation processing
Communication
C358S509000
Reexamination Certificate
active
06778290
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of printing image frames from a digital image file of a motion picture.
BACKGROUND OF THE INVENTION
Digital images have been printed onto a photosensitive medium using a liquid crystal display (LCD) as a modulator. The image presented on the LCD modulator is optically focused on the medium and a source or sources of light is allowed to illuminate the LCD modulator, which then creates a latent image on the medium. The wavelength of the light source needs to be carefully selected or tuned to match the spectral sensitivity of the medium in order to create an image with color and density as was intended by the data in the digital image file. When printing images on traditional color motion picture film, three primary sources of monochromatic red, green and blue light would be used to illuminate the LCD modulator to create the image. Each primary color corresponds to one of the three separable color records in the digital image data and color planes on the medium. For a single LCD modulator, each of the three separable planes on the medium would be exposed sequentially by the respective separable color records in the image file and the illumination source. The wavelength of these sources would generally be in the approximate range of 650 nm (red), 540 nm (green) and 450 nm (blue). For a monochromatic image only one image plane is on the medium, therefore only one of the three sources of light would be used to create the image. The choice of the illumination source wavelength would depend on the spectral sensitivity of the medium.
Digital motion picture image printers in use today uses a variety of technologies to perform the task. These systems employ technologies that are based on cathode ray tubes (CRT), raster scan laser beam and electron beam writing engines. These technologies as used in their current level of maturity are known to have inherent limitations. CRT systems such as that described in U.S. Pat. No. 4,754,334 are slow and generally do not have the capability to create images that make use of the full exposure range of the motion picture film because of the low radiance output of the CRT. It takes approximately 20 seconds to print a 2 k-resolution full aperture image using this system. The raster scan systems employs a spinning mirror called a scanner to impart motion to a focused modulated laser beam to expose and build the image one pixel at a time. A 2 k-resolution image can contain over 6 million pixels. The raster scan system may contain a single mirror or multi-mirror scanner. The limitations in such systems as described in U.S. Pat. No. 5,296,958 are due primarily to the limitations in speed of the scanner. The raster scan system is also relatively complex in its construction. It is estimated that the top end printing speed in a single beam, single scanner system is about 0.2 seconds per a 2 k-resolution image using current commercial components and technology. Electron beam systems are complex and the need to use special film types is a hindrance.
It is not practical to simply scale up these systems in order to gain speed. As an example, in order to print faster using a raster scan laser beam recorder, one could increase the speed of the scanner. Single mirror scanners (monogons) currently operate at approximately 65,000 RPMs, which is approximately the top end of their capabilities. Multi-mirror scanners (polygons) with 16 mirror facets are currently used today operating at approximately 6,500 RPM. In order to print faster, the scanners will have to operate at higher speeds but there are practical limitations relative to speed, the number of scanner mirrors, and the diameter of the scanner disk and cost. For example, the scanner motor loading varies as a function of the fifth power of the diameter and the square of the speed. It is possible to go faster but such an effort would result in added complexity, such as placing the scanner in a vacuum chamber to protect it and reduce drag. The power density of the writing spot may have to increase and the exposure time may have to decrease which could lead to reciprocity failures in the photosensitive medium.
A single two hour motion picture film sequence contains 172,800 high resolution discrete images. It is becoming common to see more motion picture films originating from digital sources. To this end, there is a need to be able to print these images in totality in a very short period of time to meet the needs of the digital mastering market. Using the best of the current technologies it would take approximately 192 hours to print these 2 k resolution images on 35 mm film using one machine. There is a need in the industry to reduce this time to less than 10 hours.
Two-dimensional spatial light modulators, such as those using a digital micromirror device (DMD) from Texas Instruments, Dallas, Tex., or using a liquid crystal display (LCD) from Victor Company of Japan, Limited (JVC) can be used to modulate an incoming optical beam for imaging. A spatial light modulator can be considered essentially as a two-dimensional array of light-valve elements, each element corresponding to an image pixel. Each array element is separately addressable and digitally controlled to modulate incident light from a light source by modulating the polarization state of the light. Polarization considerations are, therefore, important in the overall design of support optics for a spatial light modulator.
There are two basic types of LCD spatial light modulators currently in use, transmissive and reflective, respectively. Spatial light modulators have been developed and used for relatively low resolution applications such as digital projection systems and image display in portable devices such as TV and helmet display. Applications and teachings can be found in U.S. Pat. Nos. 5,325,137, 5,808,800, and 5,743,610. The requirements for projection and displays systems differs significantly from the requirements for high resolution printing to a photosensitive medium as would be required, for example, by the motion picture industry. The images from the first generation high resolution photosensitive medium will ultimately be used for creating a print film to be used for projection on a screen in a theatre. The process for creating the final projectable photosensitive medium would involve several generations of duplications and modifications by computer systems prior to the creation of the projectable medium. When viewing these intermediate high resolution photosensitive medium outputs or electronically scanning the original medium with a high resolution scanner, image artifacts, aberrations and nonuniformity will be more obvious. Optical systems for projectors and display applications are designed for the response of the human eye which, when viewing a display, is relatively insensitive to image artifacts, aberrations and nonuniformity, since the displayed image is continually refreshed and is viewed from a distance. Even more significant are differences in resolution requirements. Adapted for the human eye, projection and display systems are optimized for viewing at typical resolutions such as 72 dpi or less, but photographic printing used in the motion picture industry is generally printed at resolutions in excess of 1900 dpi. As a result of these requirements the optical, illumination, and image processing systems for a motion picture printer used in the motion picture industry can vary significantly from the aforementioned systems.
The current available resolution using digital micromirror device (DMD), as shown in U.S. Pat. Nos. 5,061,049 and 5,461,411 is not sufficient for the printing needs of the motion picture film industry and there is no clear technology path to increase the resolution. DMDs are expensive and not easily scaleable to higher resolution.
Low cost solutions using LCD modulators are described in U.S. Pat. Nos. 5,652,661, 5,701,185, and 5,745,156. Most involve the use of transmissive LCD modulators. While such a method offers several advantages in ease of opti
Druzynski Richard L.
Oehlbeck Martin E.
Yarid Rockwell N.
Eastman Kodak Company
Owens Raymond L.
Wallerson Mark
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