Television – Format conversion – Line doublers type
Reexamination Certificate
1998-06-02
2001-07-10
Kostak, Victor R. (Department: 2611)
Television
Format conversion
Line doublers type
C348S448000
Reexamination Certificate
active
06259480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sequential scanning converter for converting a picture signal of interlaced scanning to a sequential scanning scheme by scanning line interpolation, and displaying it, and particularly, to a sequential scanning converter which improves the picture quality degradation caused by scanning conversion.
2. Related Art of the Invention
The current television-system employs an interlaced scanning scheme. In the interlaced scanning scheme, two fields, odd and even fields, form one frame. Thus, for instance, in the HDTV system, the number of scanning lines per frame is 1,125, but, if the viewing distance becomes short, the coarse scanning line structure forming each field becomes visible, causing degradation in the picture quality.
As a method for improving the scanning line structure, there is a scheme in which a video signal is interpolated between the upper and lower scanning lines in a field so as to be converted to the sequential scanning, but the frame made by this has a problem that the sharpness of the vertical direction decreases to affect the picture quality.
As a conventional sequential scanning converter, to solve the above problem, for instance, a sequential scanning converter for improving the picture quality degradation due to the sequential scanning by simple two scans through controlling the brightness of the interpolation signal for sequential scanning according to the brightness of the picture signal (for instance, “Sequential Scanning Converter Circuit,” “Japanese Patent Application Laid-Open No. 63-179685), or a sequential scanning converter for preventing apparent degradation of the sharpness by decreasing the amplitude of the interpolation signal after sequential conversion (for instance,” “Television Display of Clearvision System,” “Japanese Patent Application Laid-Open No. 4-95479)” was filed.
However, in the above conventional arrangement, a quasi-interlace effect is obtained by decreasing the amplitude-of interpolation lines in the conversion to the sequential scanning as compared with the amplitude of real lines, thereby to enable an apparent increase in the sharpness of the vertical direction, but, it has a problem that, since there is a difference between the amplitudes of real and interpolation lines for a signal having no gradation such as an animation created by computer graphics (hereinafter referred to as CG), the occurrence of streaks greatly degrades the picture quality. In particular, the picture quality degradation becomes remarkable as the screen becomes larger and larger in recent years.
SUMMARY OF THE INVENTION
The present invention is to solve the above traditional problem, and it Is the object of it to provide a sequential scanning converter for playing back a natural picture while holding the sharpness, and faithfully playing back a picture having no gradation such as an animation created by CG or the like.
To accomplish the above object, the first-invention comprises:
an interpolation scanning line generating means for generating interpolation scanning lines from an input video signal;
a motion detecting means for detecting the motion amount of the input video signal;
an amplitude control means for controlling the amplitude of the output signal of the interpolation scanning line generating means according to the output of the motion detecting means; and
a sequential scanning converting means for performing the conversion to a sequential scanning signal by using the input video signal and the output of the amplitude control means.
The second invention comprises:
an interpolation scanning line generating means for generating interpolation scanning lines from an input video signal;
a flat portion detecting means for detecting the flat portion of the input video signal;
an amplitude control means for controlling the amplitude of the output signal of the interpolation scanning line generating means according to the output signal of the flat portion detecting means; and
a sequential scanning converting means for performing the conversion to a sequential scanning signal by using the input video signal and the output signal from the amplitude control means.
The third invention comprises:
an interpolation scanning line generating means for generating interpolation scanning lines from an input video signal; a motion detecting means for detection the motion amount of the input video signal;
a flat portion detecting means for detecting the flat portion of the input view signal;
a judging means for making a judgment with the output signal of the motion detecting means and the output signal of the flat portion detecting means;
an amplitude control means for controlling the amplitude of the output signal of the interpolation scanning line generating means according to the output signal of the judging means; and
a sequential scanning converting means for performing the conversion to a sequential scanning signal by using the input video signal and the output signal from the amplitude control means.
The fourth invention comprises:
an interpolation scanning line generating means for generating interpolation scanning lines from an input video signal;
a motion detecting means for detecting the motion amount of the input video signal;
a freeze-frame picture judging means for judging the freeze-frame picture in a field from the output signal of the motion detecting means;
a flat portion detecting means for detecting the flat portion of the input video signal;
a flat portion judging means for judging the flat portion in a field from the output signal of the flat portion detecting means;
a frequency judging means for detecting the freeze-frame picture of at least one field and the frequency of the flat portion from the output signal of the freeze-frame picture judging means and the output signal of the flat portion judging means;
an amplitude control means for controlling the amplitude of the output signal of the interpolation scanning line generating means according to the output signal of the frequency judging means; and
a sequential scanning converting means for performing the conversion to a sequential scanning signal by using the input view signal and the output signal from the amplitude control means.
The fifth invention constructed so that the group of scanning line delays in the high-frequency extraction means in the flat portion detecting means is shared by the group of scanning line delay means in the motion detecting means.
REFERENCES:
patent: 4403250 (1983-09-01), Kellar
patent: 4679084 (1987-07-01), Topper et al.
patent: 4761686 (1988-08-01), Willis
patent: 4967271 (1990-10-01), Campbell et al.
patent: 5534935 (1996-07-01), Kawai et al.
patent: 5625421 (1997-04-01), Faroudja et al.
Seki Yoshio
Tagami Tomohisa
Yamauchi Hideaki
Kostak Victor R.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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