Noise reducer using memory

Details Noise reducer using memory Noise reducer using memory

1997-06-25

2001-03-20

Powell, Mark R. (Department: 2779)

Television

Image signal processing circuitry specific to television

Noise or undesired signal reduction

C348S606000, C348S618000, C348S622000, C386S349000, C386S349000

Reexamination Certificate

active

06204890

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a noise reducer and, more particularly, to noise reduction using a memory.
2. Description of Related Art
Various kinds of noise reducers (hereinafter referred to as NR circuits) for reducing a noise component of an input signal have heretofore been considered.
A particular kind of NR circuit using a memory, i.e., a so-called time-cyclic NR circuit, is widely used in a recent type of image processing apparatus as an NR circuit for an image signal because its effect is large in spite of its simple algorithm.
However, this kind of NR circuit needs a memory in principle, and the more the number of pixels of an image signal to be handled, the larger the required capacity of the memory.
For example, in recent years, there have been proposed a system which processes a high-definition video signal the number of pixels of which is approximately twice the number of pixels of an NTSC video signal, i.e., a so-called HD video signal, and a system using a progressive scanning type of image pickup element which outputs an image signal for one frame per {fraction (1/60)} of a second instead of a conventional interlaced scanning type of image pickup element which outputs an image signal for one frame per {fraction (1/30)} of a second.
In the above-described systems, to realize the aforesaid NR circuit, it is necessary to use a memory having a capacity which is approximately twice or more times the memory capacity of the system using the interlaced scanning type of image pickup element.
BRIEF SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to solve the above-described problems.
Another object of the present invention is to make it possible to effectively reduce noise in a signal by means of a simple and inexpensive arrangement.
Another object of the present invention is to make it possible to effectively reduce noise even in a system using a progressive scanning type of image pickup element without increasing the required circuit scale.
To achieve the above-described objects, according to one aspect of the present invention, there is provided an image signal processing apparatus which comprises separating means for separating an input image signal into a first image signal and a second image signal, noise reducing means having a memory and arranged to apply noise reduction processing to the first image signal by using the memory, and combining means for combining the first image signal processed by the noise reducing means and the second image signal.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description of an embodiment of the present invention, taken in conjunction with the accompanying drawings.


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patent: 5822011 (1998-10-01), Rumreich

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