Television – Image signal processing circuitry specific to television – Transition or edge sharpeners
Reexamination Certificate
1997-03-31
2001-12-11
Eisenzopf, Reinhard J. (Department: 2614)
Television
Image signal processing circuitry specific to television
Transition or edge sharpeners
C348S628000, C348S687000, C348S622000, C348S627000
Reexamination Certificate
active
06330038
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to video technology and, more particularly, to the enhancement of a video image.
2. Description of the Related Art
For most people in the United States, television is a normal part of their everyday lives. Television entertains, relaxes, and informs. In fact, using satellite communication, televisions have been generally credited with bringing the world closer together in the last twenty to thirty years.
It is, therefore, somewhat ironic that television technology arose out of the development of RADAR during World War II, from which evolved the high frequency circuits necessary for the introduction of television in 1945. Television became instantly popular, and technological advances over the past fifty years have enhanced its popularity. The improvements seem to be never ending. Just a few of the more significant improvements include: color picture, electronic tuners, coaxial cable signal transmission, the replacement of vacuum tube circuits with solid state circuits, and, of course, infrared remote controls.
Although the technologic advancement of the past fifty years has greatly improved television in almost every way imaginable, from picture quality to reliability, the television that we watch today still uses the standard developed by the National Television Systems Committee (NTSC) in the late 1940s. The incorporation of color in the NTSC standard approximately forty years ago marked its last major advancement. The NTSC's standardization activities were subsequently emulated throughout the world, leading to the development of other standards such as PAL and SECAM. Although new standards have been proposed from time to time in an effort to promote further forward leaps in technology for the improvement of television, the United States government and most foreign governments have been somewhat reluctant to stray from these long standing standards. The primary reason for this reluctance appears to be the governments' desire to protect the investments consumers have made in their television equipment. In other words, any new standard must be compatible with television equipment that consumers may have purchased many years before.
By way of example, let us consider the circumstances surrounding the evolution of television from its monochromatic (black and white) roots to the color video images that we are all familiar with today. For more than a decade after its introduction, television images were monochromatic. In other words, the video signal conveyed information relating primarily to brightness variations, much as does a black and white photograph. This monochromatic video signal is typically referred to as a luminance signal. However, to describe a color, the video signal needed to contain additional information. The government determined that any color system must produce a signal that is recognizable to a monochrome receiver as well as a color receiver, so that the viewer has a choice between a black and white television set or a color television set. Therefore, to incorporate the color information in the transmission signal, the NTSC determined that the luminance signal would remain unchanged and that the color signal would be added to the luminance signal. This color signal is typically referred to as the chrominance (or chroma) signal.
In color television sets, the analog luminance and chrominance signals are converted to a red-green-blue (RGB) format and used to drive the RGB electron guns that, in turn, excite the phosphors on the picture tube to produce the desired color video images. As most viewers know, various characteristics of a color video image may be adjusted to suit a viewer's taste. Such characteristics include brightness, contrast, color strength, tint, and sharpness. While each of these characteristics is important for the viewer's enjoyment of the television, the sharpness characteristic has become particularly important in this new era of digital television, multimedia, and PC TV. This newfound importance results from the increased use of graphics in the video images displayed by television monitors. These graphics may be superimposed on a typical broadcast video image, or the graphics may be displayed by the television monitor when used as a computer monitor.
The present invention is directed to overcoming, or at least reducing the affects of, one or more problems set forth above.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided a method of improving sharpness of a video image. The method includes the steps of: (a) receiving a luminance signal; (b) filtering the luminance signal to generate a filtered luminance signal that has frequency components at least nine decibels higher than the luminance signal from about 2.0 MHz to about 4.25 MHz; and (c) creating a video image correlative to the filtered luminance signal.
In accordance with another aspect of the present invention, there is provided a method of improving sharpness of a video image. The method includes the steps of: (a) receiving a luminance signal; (b) boosting frequency components of the luminance signal by at least nine decibels from about 3.0 MHz to about 4.0 MHz to generate a boosted luminance signal; and (c) using the boosted luminance signal to generate a video image.
In accordance with still another aspect of the present invention, there is provided a method of enhancing a video image. The method includes the steps of: (a) receiving a luminance signal that has a black signal portion, a white signal portion, and a transitional signal portion between the black signal portion and the white signal portion, the transitional signal portion having a dark gray signal portion and a light gray signal portion; (b) converting at least 50 percent of the light gray signal portion to the white signal portion to produce a converted luminance signal; and (c) creating a video image using the converted luminance signal.
In accordance with yet another aspect of the present invention, there is provided a video image. The video image includes a luminance signal having frequency components, the frequency components having a gain of at least nine decibels between about 3.0 MHz and about 4.0 MHz.
In accordance with a further aspect of the present invention, there is provided a digital television system. The system includes a video processor that is arranged to receive a luminance signal. The video processor includes a prefilter, a band pass filter, and a weighting stage. The prefilter receives the luminance signal and filters the luminance signal to generate a prefiltered luminance signal. The band pass filter receives the prefiltered luminance signal and filters the prefiltered luminance signal to generate a filtered luminance signal. The weighting stage receives the filtered luminance signal and weights the filtered luminance signal to produced a weighted luminance signal. A graphics controller receives the weighted luminance signal and creates a video image signal correlative to the weighted luminance signal. A monitor receives the video image signal and displays a video image correlative thereto.
In accordance with an even further aspect of the present invention, there is provided a device for improving sharpness of a video image. The device includes means for receiving a luminance signal. The device also includes means for boosting frequency components of the luminance signal by at least nine decibels from about 2.0 MHz to about 4.25 MHz to generate a boosted luminance signal. The device further includes means for generating a video image using the boosted luminance signal.
In accordance with a still further aspect of the present invention, there is provided a device for enhancing a video image. The device includes means for receiving a luminance signal that has a black signal portion, a white signal portion, and a transitional signal portion between the black signal portion and the white signal portion. The transitional signal portion has
Akin Gump Strauss Hauer & Feld & LLP
Compaq Computer Corporation
Eisenzopf Reinhard J.
Lo Linus H.
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