Television – Image signal processing circuitry specific to television – Matrixing or mixing
Reexamination Certificate
1999-10-07
2003-09-16
Lee, Michael H. (Department: 2714)
Television
Image signal processing circuitry specific to television
Matrixing or mixing
C348S453000, C345S604000
Reexamination Certificate
active
06621526
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a colorimetry converting apparatus.
2. Description of the Prior Art
A colorimetry converting apparatus for converting a single video signal having a colorimetry to another single video signal having different colorimetry is known.
There are various types of video signals having different formats which are compressed by different compression methods. For example, the motion picture video signal is compressed in accordance with MPEG (Motion Picture Expert Group) 2 and the still picture signal is compressed in accordance with JPEG (Joint Photographic Coding Experts Group). Moreover, characters are represented by characters codes and figures are expressed by the PNG (portable Network Graphics) format.
Both the MPEG 2 and JPEG use Y (luminance), Cr and Cb (Color difference signals) as original data. On the other hand, graphics data like PNG uses RGB as original data. However using the same Y, Cr, Cb as original data, the transfer matrix from YCrCb to RGB (or vice versa) is different among various compression or graphic formats.
For the monitors, RGB and YCrCb are both used. So when the monitor has YCrCb inputs, RGB signal should be again transferred to YCrCb signal according to the colorimetry of the monitor.
Moreover, conversion methods of satellite broadcast video signals are different from one country to another country.
On the other hand, in U.S.A. 1080I format (which is interlace scan and the effective lines are 1080) and 720P format (which is progressive scan and the effective lines are 720) have the colorimetry of BT 709, while 480I format (which is interlace scan and the effective lines are 480) and 480P format (which is progressive scan and the effective lines are 480) have the colorimetry of BT601.
Moreover, in the case of the monitor, both in U.S.A. and Japan, the video signals according to 1080I and 720P format should be inputted using the colorimetry BT709, while the video signals according to 480I and 480P format should be inputted using the colorimetry BT601.
Moreover, the colorimetry most frequently used in JPEG data is SMPTE (Society of Motion Picture and Television Engineers) 240M.
The following equations Eq. 1, Eq. 2, and Eq. 3 are conversion equations for converting RGB video signals according to BT601, BT709, and SMPTE 240M to YCrCb video signals, respectively. The following equations Eq. 4, Eq. 5, and Eq. 6 are conversion equations for converting YCrCb video signals according to BT601, BT709, and SMPTE 240M to RGB video signals, respectively.
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Ey
Ecr
Ecb
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0
.299
0.587
0.
114
0
.5
-
0.419
-
0.
081
-
0
.169
-
0.331
0.
5
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Er
Eg
Eb
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(
EQ
.
1
)
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Ey
Ecr
Ecb
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=
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0
.2126
0.
7152
0.
0722
0
.5
-
0.
454
-
0.
046
-
0
.115
-
0.
385
0.
5
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Er
Eg
Eb
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(
EQ
.
2
)
&LeftBracketingBar;
Ey
Ecr
Ecb
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=
&LeftBracketingBar;
0
.212
0.
701
0.
087
0
.5
-
0.
445
-
0.
055
-
0
.116
-
0.
384
0.
5
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Er
Eg
Eb
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(
EQ
.
3
)
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Eg
Eb
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=
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1
.0
1.
4016867602
-
0.
0009267448
1.0
-
0.
7141690400
-
0.
3436953845
1.0
0.
0009902205
1.
7721604157
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Ey
Ecr
Ecb
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(
EQ
.
4
)
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Er
Eg
Eb
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=
&LeftBracketingBar;
1
.0
1.
5749131625
0.
0004920110
1.0
-
0.
4683216869
-
0.
1874855952
1.0
0.
0016223285
1.
8557492542
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Ey
Ecr
Ecb
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(
EQ
.
5
)
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Er
Eg
Eb
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=
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1
.0
1.
5758476316
-
0.
0006567605
1.0
-
0.
4765290206
-
0.
2264181923
1.0
0.
0003776373
1.
8259584599
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Ey
Ecr
Ecb
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(
EQ
.
6
)
In Eqs. 1 to 6, each Ey is an analog value from zero to one, each Ecr and each Ecb are analog values from −0.5 to 0.5 and each Er, each Eg, and each Eb are analog values from zero to one.
Moreover, values of digital values of Y, Cr, and Cb actually used in MPEG method are calculated in accordance with the following equation.
Y
=219
×Ey
+16
Cr
=224
×Ecr
+128
Cb
=224
×Ecb
+128 (EQ. 7)
As mentioned, the conversion equations, that is, colorimetries are different each other among the compression methods or standards (formats) of video signals. The prior art colorimetry conversion apparatus converts one type of video signal having one colorimetry to another video signal having another colorimetry independently.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior colorimetry converting apparatus.
According to this invention, there is provided a first colorimetry converting apparatus including: an input circuit for receiving a plurality of input video signals respectively having different first colorimetries; and a colorimetry converting circuit for converting the input video signals to a single output video signal having a second colorimetry.
In the first colorimetry converting apparatus, the different types of input video signals may be inputted to the input circuit in parallel.
In the first colorimetry converting apparatus, the different types of input video signals may be successively inputted to the input circuit.
In the first colorimetry converting apparatus, the outputting circuit may time-divisionally output the second video signals within a frame of the single output video signal.
The first colorimetry converting apparatus may further include an area signal generation circuit for generating an area signal indicative of a partial area of a frame of the single output video signal. The colorimetry converting circuit converts one of the input video signals to the single output video signal at the partial area and converts another one of the input video signals at outside of the partial area in accordance with the area signal.
Each of the input video signals in the first colorimetry converting apparatus may include a luminance signal and color difference signals and the colorimetry converting circuit includes, as a second colorimetry converting apparatus, a first switch for outputting a part of the input video signals, a first converting circuit converting the part of input video signals from the first switch to RGB-color signals in accordance with the colorimetries of the part of input video signals from the first switch respectively, a second switch for outputting one of the RGB-color signals, and a second converting circuit for converting the RGB-color signal to the single video signal including a luminance signal and color difference signals.
The first colorimetry converting apparatus may further include, as a third colorimetry converting apparatus, another input circuit for receiving an input RGB-color signal. Each of the input video signals includes a luminance signal and color difference signals. The colorimetry converting circuit includes a first switch for outputting a part of the input video signals, a fi
Lee Michael H.
Victor Company of Japan Ltd.
Woo Louis
Yenke Brian
LandOfFree
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