Television – Modular image display system
Reexamination Certificate
1998-09-23
2001-04-17
Kostak, Victor R. (Department: 2611)
Television
Modular image display system
74, 74
Reexamination Certificate
active
06219099
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to calibrating displays, and more particularly, to calibrating tiled displays that use multiple display devices to produce larger and/or higher resolution images.
Tiled display systems, and in particular tiled projection systems, have been proposed and used for many years. In the 1950s, the “CINERAMA” system was developed for the film industry. The CINERAMA system projected three films using three separate projection displays, which were combined to form a single panoramic image. Disneyland continues to use a similar multiple projector system. At Disneyland, a circle of projectors shine onto a screen that circles the wall of a round room.
In the video field, multiple projector systems have been proposed and used for a number of specialty applications. For example, U.S. Pat. No. 4,103,435 to Herndon and U.S. Pat. No. 3,833,764 to Taylor suggest using multiple projector systems for flight simulators. In many of these systems, multiple video screens are placed next to each other to form a large image display for multiple projectors. A difficulty with many of the video based multiple projector display systems is making the multiple images appear as one single continuous image on the display screen.
When two images are projected side-by-side on a single screen, there is normally a seam between the images. The final display image will either appear as two images placed side-by-side with a gap in between or, if the images are made to overlap on a single screen, there will be a bright line where the two images overlap. Because of the inconsistencies in conventional cameras, video processing and delivery channels in displays and, specifically, projection displays, it is exceedingly difficult to perfectly match the resultant video images so that no tiling artifacts appear among the images. If the images are brought very close together on the same screen, there is typically both gaps and overlaps at each seam.
The article entitled
Design Considerations and Applications for Innovative Display Options Using Projector Arrays
, by Theo Mayer, SPIE Vol. 2650 (1996), pp. 131-139, discloses projecting a number of discrete images in an overlapping relation and ramping the brightness of the discrete images in the overlapping regions of each image. Mayer discloses using a blending function to fade down each overlapping edge of the discrete images in such a way so as to compensate for the gamma (video signal reduction vs. light output curve) of a phosphor, light valve or LCD projector, with the goal of producing a uniform brightness across the display.
U.S. Pat. No. 5,136,390 to Inova et al. recognizes that the blending function typically cannot be a simple even ramping function. A typical video projector produces an image that becomes darker toward the edges of the image as a natural function of the lens system used, and has a number of bright and dark portions caused by normal irregularities in the signal, intermediate signal processor, projector, screen, etc. These inconsistencies typically vary from one video component to another, and even among different components with similar construction. Also, different types of projectors often respond differently to the same amount of brightness modification. Thus, a simple ramp of the brightness in the over-lapping regions can produced light and dark bands and/or spots in the resulting image.
To overcome these limitations, Inova et al. suggest applying a simple even blending function to the overlapping regions of the image, as suggested by Mayer, but then manually tuning the simple even blending function at specific locations to remove the visible artifacts from the display. The location of each artifact is identified by manually moving a cursor over each location that is identified as having an artifact. Once the cursor is in place, the system tunes the corresponding location of the blending function so that the corresponding artifacts are removed.
Since each artifact must be manually identified by a user, the process of calibrating an entire display can be time-consuming and tedious. This is particularly true since many displays require periodic re-calibration because the performance of their projectors and/or other hardware elements tend to change over time. In view of the foregoing, it would be desirable to have a display that can be calibrated and re-calibrated with less manual intervention than is required by Inova et al and others.
SUMMARY OF THE INVENTION
The present invention overcomes many of the disadvantages of the prior art by providing a display that can be calibrated and re-calibrated with little or no manual intervention. To accomplish this, the present invention provides one or more cameras for capturing an image that is shown on a display viewing surface or viewing screen. In one illustrative embodiment, the one or more cameras are placed on the viewing side of the displays. In another illustrative embodiment, the one or more cameras are place on the non-viewing side of the displays, for example between the backlight and an adjoining LCD or on the inside and rear of the vacuum bottle in the case of a CRT.
In one illustrative embodiment, the one or more cameras are placed on the same side of the screen as the projection display. In another illustrative embodiment, an array of cameras is provided on either or both sides of the screen for capturing a number of adjacent and/or overlapping capture images of the screen. In any case, the resulting capture images are processed to identify any non-desirable characteristics therein including any visible artifacts such as seams, bands, rings, etc. Once the non-desirable characteristics are identified, an appropriate transformation function is determined. The transformation function is used to pre-warp the input video signal to the display such that the non-desirable characteristics are reduced or eliminated from the display. The transformation function preferably compensates for spatial non-uniformity, color non-uniformity, luminance non-uniformity, and/or other visible artifacts.
In one illustrative embodiment, a screen is provided that has a first side and a second side. For a rear projection display, the first side may correspond to the projection side, and the second side may correspond to the viewing side. For a front projection display, the first side may correspond to both the projection and viewing side of the screen. In one illustrative embodiment, a projector is provided for projecting an image onto the projection side of the screen, and a camera or camera array is provided for capturing a capture image or capture image segment from the projection side of the screen. A determining block is provided for receiving the capture image(s), and determining if the capture image(s) has one or more non-desirable characteristic. An identifying block may also be provided for identifying a transformation function that can pre-warp the input video signal such that the non-desirable characteristics are reduced or eliminated from the composite display.
It is contemplated that two or more displays and, specifically projectors, may be provided, wherein each of the displays manifests a discrete image so that the discrete images collectively form a composite image on the screen. It is also contemplated that two or more cameras may be provided. When two or more cameras are provided, it is contemplated that the cameras may be provided on either or both sides of the screen, and may capture a number of adjacent and/or overlapping capture images of the screen. Preferably, each of the cameras is paired with one of the displays, thereby forming a number of display/camera clusters. Each of the display/camera clusters preferably include a number of electromechanical interfaces for providing interfaces with neighboring display/camera clusters, and allowing the joinder of two or more clusters to form an overall display.
It is contemplated that when more than one display is provided, the identifying block may identify a separate transformation function for each disp
Chandrasekhar Rajesh
Chen Chung-Jen
Johnson Michael J.
Honeywell International , Inc.
Kostak Victor R.
Shudy, Jr. John G.
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