Television – Image signal processing circuitry specific to television – Transition or edge sharpeners
Reexamination Certificate
2000-02-04
2004-02-10
Lee, Michael H. (Department: 2614)
Television
Image signal processing circuitry specific to television
Transition or edge sharpeners
C348S630000, C348S606000, C348S252000, C382S263000, C382S266000, C358S532000
Reexamination Certificate
active
06690429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video compression and transmission system, and more particularly, to a device and method for processing a color signal.
2. Background of the Related Art
Generally, sharpness of an image depends on the contrast at the edge of the image. Particularly, an image is perceived to be sharper to human vision as the contrast at the edge of a first image and a second image becomes greater. In a video compression and transmission system, a luminance signal is passed through high pass frequency filtering or a second order derivative is added to an original signal to enhance the contrast at the edge of an image.
However, if a color signal is passed through high pass frequency filtering, the chroma is distorted at the image edge. Moreover, the high frequency component of the color signal is removed during the signal processing, resulting in a smooth image edge. Therefore, the color signal not only has a lower resolution than the luminance signal, but also has distortion at the image edge.
Particularly, the chroma distortion appears due to a slow change of the color signal at the edge, called color transient. Therefore, the color signal can be made sharper by improving the color transient using, for example, a process which converts the slowly changing edge to a rapidly changing edge. Similar to the processing of the luminance signal, a method in the related art proposes to add a second order derivative to an original signal to make the edge change rapidly. However, this may cause an over shoot or an under shoot at the edge. Therefore, the above method is not preferable due to chroma distortion from over shoot and under shoot.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the present invention is to provide a device and method for processing a color signal which results in a sharp image.
Additional advantages, objects and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, a device for processing a color signal includes a maximum value generator for delaying an input color signal by N successive taps, selecting and outputting a maximum value from the delayed signal, where N is a natural number; an original signal generator for delaying the input color signal by (N+1)/2 taps; a minimum value generator for delaying the input color signal by N successive taps, selecting and outputting a minimum value from the delayed signal; a selector for selecting and outputting one of the maximum value, the original color signal or the minimum value; and a selection controller for generating a selecting signal from the maximum value, the original color signal and the minimum value.
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Birch & Stewart Kolasch & Birch, LLP
Desir Jean W.
Lee Michael H.
LG Electronics Inc.
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