Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2001-01-11
2002-06-18
Diep, Nhon T (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C348S097000
Reexamination Certificate
active
06408024
ABSTRACT:
TECHNICAL FIELD
The present invention relates to telecine video signal detectors in color television receivers and, more specifically, to a telecine video signal detector capable of sequentially detecting even an insuccessive telecine video signal produced due to editing or the like.
BACKGROUND ART
In recent years, various video reproducing methods are available in television, and the need for improving image quality is growing more. When video signals are reproduced through sequential scanning of interlace signals, the importance lies in detection of a telecine video signal produced through conversion from 24-frame film video to an interlace signal with the use of a 2-3 pulldown scheme and recovery of the signals corresponding to the video before telecine conversion, for the purpose of suppressing deterioration in image quality due to interlacing, and improving image quality.
Shown in
FIG. 13
is the structure of a conventional telecine video signal detector. A telecine video signal detector Dtc includes a pre-filter
100
, a 1-frame delay circuit
120
, a motion vector detection circuit
140
, a comparison and detection circuit
160
, a majority circuit
180
, a 5-field delay circuit
200
, and a decision circuit
220
. The pre-filter
100
eliminates noise in a video signal Sv′ provided from an external video signal source (not shown) to the telecine video signal detector Dtc to produce a video signal Sv. The 1-frame delay circuit
120
delays the video signal Sv produced by the pre-filter
100
by one frame (2 fields) to produce a delayed video signal Svd.
The motion vector detection circuit
140
compares the delayed video signal Svd produced by the 1-frame delay circuit
120
and the present video signal Sv each other for detecting a motion of video between fields, and then produces a plurality of motion vectors Sm.
The comparison and detection circuit
160
compares the plurality of motion vectors Sm produced by the motion vector detection circuit
140
with a reference value (&agr;, &bgr;). The comparison and detection circuit
160
then outputs, as small-motion vectors Sms, motion vectors that are smaller than the reference value (&agr;, &bgr;) among the motion vectors Sm.
The majority circuit
180
takes frequency distribution of the small-motion vectors Sms outputted from the comparison and detection circuit
160
, detects the small-motion vectors equal in size, and provides the detection result to the 5-field delay circuit
200
and the decision circuit
220
.
The decision circuit
220
counts the number of small-motion vectors Sms equal in value that are not larger than the reference value (&agr;, &bgr;), and generates a decision signal SF for deciding that the video signal is a telecine video signal, every time a field in which the number of small-motion vectors is not smaller than a predetermined value &ggr; appears for every five fields.
In the above-structured conventional telecine video signal detector Dtc, attention is given to the field in which the number of motion vectors equal in value for one frame (two fields) are not smaller than the predetermined value. When such field appears for every five fields, it is decided that the video signal is a telecine video signal. This decision concept will be further described later with reference to FIG.
14
.
With reference to
FIGS. 14
,
15
, and
16
, a decision operation in the decision circuit
220
of the telecine video signal detector Dtc is now described in detail. Shown in
FIG. 14
are various signals observed in the decision circuit
220
.
First, in
FIG. 14
, Cc
1
through Cc
22
shown in the top row each represent a control cycle in the telecine video signal detector Dtc. Note that, in the present example, the control cycles Cc
1
through Cc
22
each correspond to a field period of the video signal Sv. The video signal Sv is provided for every field period in order of field data A
1
, A
2
, B
1
, B
2
, B
1
, C
2
, C
1
, D
2
, D
1
, D
2
, E
1
, E
2
, F
1
, F
2
, F
1
, G
2
, G
1
, H
2
, H
1
, J
2
, K
1
, L
2
, . . .
Each field data is identified by an identifier generated by adding a numerical suffix to a letter of the alphabet. Each alphabet letter represents an original image from which the data is generated, while each numerical suffix represents a position of the data field in those generated from the same image. In other words, in the above-stated video signal Sv, the alphabet letters A, B, C, D, E, F, G, H, J, K, and L each represent field data of each independent image. As stated above, pieces of field data represented with different suffixes (
1
and
2
) added to the same alphabet are originally generated from the same film image and, naturally, the difference in motion of the image is extremely small between fields. Furthermore, pieces of field data with the same identifier are the same image. Thus, such pieces of field data represented by identifiers with the same alphabet but different suffixes are hereinafter referred to as same-source field data.
In view of the above, in the video signal Sv, the same-source field data A
1
and A
2
generated from the same image are placed in the control cycles Cc
1
and Cc
2
, respectively. Then, identical pieces of same-source field data B
1
are placed in the following control cycles Cc
3
and Cc
5
. In the control cycle Cc
4
therebetween, the field data B
2
generated from the same image as that for the filed data B
1
is placed.
Similarly, the same-source field data C
1
and C
2
are placed in the control cycles Cc
6
and Cc
7
; the same-source field data D
2
and D
1
in the control cycles Cc
8
and Cc
9
, respectively; and the field data D
2
that is identical to the field data D
2
(generated from the same source as that for the field data D
1
) in the control cycle Cc
10
.
The above-described scheme is called a 2-3 pulldown scheme, which is a method of converting film video data differed in frame rate into television video data in such a manner that two pieces of same-source field data and three pieces of another same-source field data (of three, two at both ends are identical field data) are placed every successive five fields. The above-stated successive five fields are hereinafter referred to as a telecine video unit Tu.
In this case, the video signal Sv is a telecine video Vt during the control cycles Cc
1
through Cc
19
, while a non-telecine video Vnt during the control cycles Cc
20
through Cc
22
. The control cycles Cc
1
through Cc
5
form a telecine video unit Tu
1
; the control cycles Cc
6
through Cc
10
form a telecine video unit Tu
2
; the control cycles Cc
11
through Cc
15
form a telecine video unit Tu
3
; and the control cycles Cc
16
through Cc
19
form a telecine video unit Tu
4
. Note that the telecine video unit Tu
4
is constructed of not five fields, but four fields. That is, the image field data J
2
is placed in the control cycle Cc
20
, in stead of the field data H
2
which is identical to the field data one frame (two fields) before and is supposed to be placed at part (tail end) of the telecine video unit Tu
4
. In other words, shown in
FIG. 14
is one example in which the telecine video Vt is switched into the non-telecine video Vnt in an incomplete state (the telecine video unit Tu of four fields).
The telecine video Vn is produced by converting cinema images of 24 frames/second into interlaced television video of 30 frames (60 fields) through the 2-3 pulldown scheme. The non-telecine video Vnt is interlaced images of 30 frames (60 fields)/second or progressive television video of 60 frames/second. Also in actual broadcasting, a mixture of such telecine video Vt and non-telecine video Vnt is distributed. Therefore, a special process has to be taken especially at the time of switching between the telecine video Vt and the non-telecine video Vnt.
On receiving an input of the above-stated video signal Sv, the decision circuit
220
decides the contents of the video signal Sv to generate internal variables IP_mode and Mode_f. The decision circuit
220
further generates an output flag F specifying the structure o
Nagao Hiroko
Toyonaga Eiichi
Diep Nhon T
Wenderoth , Lind & Ponack, L.L.P.
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