Motion vector processing circuit

Details Motion vector processing circuit Motion vector processing circuit

1999-10-05

2002-02-19

Brier, Jeffery (Department: 2672)

Computer graphics processing and selective visual display system

Computer graphics processing

Graphic manipulation

C345S589000, C345S690000

Reexamination Certificate

active

06348930

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a motion vector processing circuit for the processing of motion vector in correcting dynamic image in time-axis direction. This motion vector processing circuit is applicable, for example, to display devices such as the PDP (Plasma Display Panel) or LCD (Liquid Crystal Display) or the like having one frame divided into a plurality of subfields (or subframes) on time-sharing basis and being capable of displaying medium-gradation image.
BACKGROUND ART
Recently, the PDP and LCD have become popular as thin-type and large-screen display devices capable of displaying television pictures and the like. Conventionally, when displaying an image having medium-gradation such as that of a television picture, it has been a common practice to divide a frame into a plurality of subfields and make the subfields emit light according to the luminance level of input video signal. Such a display method of medium-gradation image differs from that of the CRT (Cathode Ray Tube) employing the dot-sequential scanning method. Therefore, some time lag occurs between the video signal generated by a television camera and a signal for display on a PDP or the like with respect to the display timing in a frame (or field), causing a blurring of the image of moving objects or formation of pseudo images. Therefore, according to prior art, in order to resolve such problems, the dynamic image is corrected by smoothing the amounts of movements of picture elements which form rapidly moving images on the basis of the detected motion vector within a frame of a video signal to be used for producing the image to be displayed.
However, as long as the motion vector processing for dynamic image correction is made on the basis of the motion vector detected within a frame, the processing in the time-axis direction adapted to the characteristic of human eye which works when following a moving object in a dynamic image cannot be applied, thereby giving rise to a problem that the corrected dynamic image will not match the function of human eye. For instance, when a motion vector detected on the basis of input video signal varies so rapidly during a frame that a human eye cannot follow, and a dynamic image is corrected on the basis of such a rapidly varying motion vector, this will cause the generation of dynamic image not harmonious with human eye.
The present invention is devised in consideration of the problems of the prior art and the object thereof lies in providing a motion vector processing circuit capable of performing the processing of motion vector in time-axis direction for enabling the dynamic image correction adapted to the movement of human eye.
DISCLOSURE OF THE INVENTION
The present invention relates to a motion vector processing circuit for correcting the dynamic image display characteristics of a display device having a frame divided into a plurality of subfields, the motion vector processing circuit comprising a motion vector difference detection means for detecting the differences among the motion vectors of N (N= any integer not smaller than 2) number of frames of video signals of the image to be displayed, a variation determination means for determining whether the value of the difference detected by the motion vector difference detection means is smaller than a preset value L
1
or not, and an output control means for outputting the motion vector of a corresponding frame when the value of the detected difference is determined to be smaller than the preset value L
1
by the variation determination means and outputting the motion vector of a frame, preceding the corresponding frame, having a detected difference smaller than the present value L
1
, when the detected difference is determined to exceed the preset value L
1
.
When the variation of the motion vector between given frames is small, that is, when the value of difference detected by the motion vector detection means is smaller than the preset value L
1
, the value of detected difference is determined to be less than the preset value L
1
by the variation determination means, so that the motion vector of the corresponding frame is output from the output control means. When the variation of the motion vector between given frames is relatively large, that is, when the value of difference detected by the motion vector difference detection means exceeds the preset value L
1
, the value of the detected difference is determined to exceed the preset value L
1
by the variation determination means, so that the motion vector of a frame, preceding the corresponding frame, having a detected difference smaller than the preset value L
1
is output. Therefore, when the variation of the motion vector is relatively small, it becomes possible for the dynamic image to be corrected by the motion vector of the corresponding frame. On the other hand, when the variation of the motion vector is relatively large, it is possible for the dynamic image to be corrected by a motion vector whose variation is smaller than that of the motion vector of the corresponding frame, whereby a dynamic image display harmonious with the function of the human eye can be realized.
Further, in the motion vector processing circuit according to the present invention, the motion vector difference detection means detects the difference D
1
between the motion vector of a present frame and the motion vector of the immediately following frame and the difference D
2
between the motion vector of the present frame and that of the immediately preceding frame; the variation determination means determines whether both the differences D
1
and D
2
is less than the preset value L
1
; the output control means outputs the motion vector of the present frame when both the differences D
1
and D
2
are determined to not exceed the preset value L
1
, and outputs the motion vector of a frame, preceding the present frame, whose difference exceeds the preset value L
1
, when at least one of the differences D
1
and D
2
is determined to exceed the preset value L
1
. When the circuit is composed in this way, construction of each component can be simplified.
Further, the variation determination means is additionally provided with a function to determine whether or not both the differences D
1
and D
2
exceed the preset value L
1
, and the output control means is additionally provided with a function to output the motion vector having value of 0 (i.e., the value of motion vector =0) when both the differences D
1
and D
2
are determined to be exceeding the preset value. L
1
. Thus, where the circuit is composed in this way, when both the differences D
1
and D
2
exceed the preset value L
1
, the output control means will not output the zero-value motion vector for correcting dynamic image, whereby excessive correction of dynamic image can be prevented even in such a case where the motion vector varies largely during successive 2 or more frames.
Further, the variation determination means is additionally provided with a function for determining whether or not the absolute values of both the differences D
1
and D
2
are exceeding the preset value L
1
, and the output control means is additionally provided with a function for outputting zero-value motion vector when it is determined that the absolute values of both the differences D
1
and D
2
exceed the preset value L
1
and the absolute value of the sum of the differences D
1
and D
2
and a function for inhibiting output of zero-value motion vector when the absolute value of the sum of the differences D
1
and D
2
is less than the preset value L
1
even if the absolute values of both the differences D
1
and D
2
exceed the preset value L
1
. When the circuit is composed in this way, even when the absolute values of both the differences D
1
and D
2
are exceeding the preset value L
1
, the output control means outputs zero-value motion vector only when the absolute value of the sum of the differences D
1
and D
2
is exceeding the preset value L
1
and inhibit the output of the zero-value motio

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