Computer graphics processing and selective visual display system – Plural physical display element control system – Optical means interposed in viewing path
Patent
1995-04-21
1999-08-31
Powell, Mark R.
Computer graphics processing and selective visual display system
Plural physical display element control system
Optical means interposed in viewing path
359569, G09G 336
Patent
active
059459670
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an apparatus and method for filling-in the region between separated pixels of an image and, in particular, to a depixelator having a random speckle pattern.
Cross-reference is made to PCT Patent Application PCT/US94/01390 for Depixelated Visual Display of Richard Dennis Rallison, filed Feb. 7, 1994, and incorporated herein by reference.
BACKGROUND INFORMATION
Electro-optically generated displays, e.g., of the type used for virtual reality displays, video camera displays, computer displays, television displays and the like, can be generated by a number of image generators, including liquid crystal displays (LCDs), light emitting diode (LED arrays), cathode ray tubes (CRTs), plasma discharge devices, electroluminescent display, and micromirror displays. Many displays produce an image composed of a multiplicity of picture elements ("pixels"). In at least some of these devices, there is a space between adjacent pixels such that each pixels is surrounded by what is perceived by the user as a dark area. Pixelated displays in which there is a space between adjacent pixels has been found to be less satisfactory for most users than a display which has been depixelated. A process of depixelation involves filling-in the area between adjacent pixels, preferably with an intensity and/or color similar to the closest pixel.
Another problem which arises in pixelated displays is found in spatially color-distributed color displays. In this type of display, each pixel is made up of three sub-pixels, each displaying one of a set of three colors (e.g., red, green, blue), and each subpixel being separated from the others in a spatial fashion. It is desired that the user should perceive a single color at each pixel, and thus for this type of display it is desirable that depixelation among each set of subpixels should be sufficient to blend the colors together, such that, for example, if the image generator outputs substantially equally-intense red, green and blue subpixels, the viewer will perceive a single white pixel at that location.
Although the advantages of depixelation, in general, as described above, are appreciated, it has been difficult to achieve practical depixelation for a number of reasons. First, depixelation often involves blurring the pixels or the edges of the pixel. However, this must be done without losing resolution or contrast of the image to an unacceptable degree. Furthermore, some depixelation schemes are expensive or difficult to design, manufacture, repair, and/or maintain, and some depixelation schemes result in undesirable optical artifacts or side effects.
One depixelation scheme is described in U.S. Pat. No. 5,303,085 issued Apr. 12, 1994, to Rallison. Depixelation of, e.g. a liquid crystal display is provided through placement of a fiber optic base plate between the liquid crystal display and a beam splitter (a fold mirror, in this case), where the base plate has a numerical aperture related to pixel size and distance. Although this device appears to be effective for the purpose, it is desirable to also provide alternative depixelation, e.g., for purposes of supply, manufacturability, economy and the like.
Another process for depixelation with a fiber optic base plate involves placing the light source for the LCD near the rear of the pixel plane, such that the image of each pixel is enlarged, and also covers a greater portion of the total picture, correspondingly decreasing the amount of dark area surrounding each pixel. Also, the small size of each pixel causes considerable diffraction of the light which passes the edge of the pixel. Further, when a fiberoptic face plate is utilized, a diffuse source of light cannot be employed because it would create an image of each pixel on the input surface of the face plate, which would be excessively large. This forces the use of an incandescent lamp, which produces more heat which can negatively affect liquid crystal displays.
Another technique for depixelation involves positioning a weak diffuser plate a short distance
REFERENCES:
patent: 5320538 (1994-06-01), Baum
patent: 5442482 (1995-08-01), Johnson et al.
patent: 5602679 (1997-02-01), Dolgoff et al.
McRuer Robert N.
Rallison Richard Dennis
I-O Display Systems, LLC
Powell Mark R.
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