JPH0775116A - Device and method for reproducing color video signal and transmitting method for color video signal - Google Patents

Abstract

PURPOSE:To obtain the reproducing device, reproducing method and transmitting method for color video signals over a wide color reproducing range. CONSTITUTION:A green G' signal with chromaticity different from that of GB and G is calculated from input RGB video signals by a matrix circuit 1, the polarity of R is decided by a polarity decision circuit 6 and when it is positive, the pair of input RGB signals is outputted from a selector 2 as it is. On the other hand, when the polarity is negative, the pair of GBG' signals calculated by the matrix circuit 1 is outputted from the selector 2, gamma correction 3 or amplification processing 4 is performed to these signals and afterwards, those signals are displayed by a display means 5 provided with pixels to be respectively emitted in four colors R, G, B and G'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image signal reproducing apparatus, a reproducing method and a transmitting method, and in particular, it is possible to reproduce a color image having a chromaticity better than ever before by expanding a color reproduction range. The present invention relates to a color video signal reproducing apparatus, a reproducing method, and a transmitting method.

[0002]

2. Description of the Related Art Conventionally, when reproducing a color image signal, a method of reproducing an arbitrary color by combining so-called three primary colors R (red), G (green) and B (blue) has been generally used. . A color video signal reproducing device according to this method is
It has a display / playback screen in which minute pixels that emit three primary colors of G and B are repeatedly arranged in a predetermined manner, and the brightness of each pixel that emits each color is controlled by R, G, and B signals. The color video signal is being reproduced. The publicly known standard television systems such as NTSC and PAL are also based on the above method. These conventional techniques are described in detail in, for example, Japan Broadcasting Corporation, Color Television.

[0003]

However, the method of reproducing a color image signal according to the above-mentioned conventional technique has a problem that the color reproduction range is narrow. That is, when color reproduction is performed using the three primary colors of R, G, and B, the chromaticity of pixels that emit light in R, G, and B is determined by CIE (Comission International).
de l'Eclairage International Lighting Commission), the chromaticity of a reproducible color image is expressed by the xy chromaticity coordinates defined by the International Lighting Commission. Each luminescent pixel corresponding to each of R, G, and B colors emits light independently. It is limited to the inside of a triangle whose vertex is the chromaticity coordinate point. Therefore, the chromaticity of an existing color is C
Although it exists in the entire horseshoe shape on the IE xy chromaticity diagram,
As described above, the chromaticity that can be represented by the conventional method of reproducing a color video signal is limited to the triangle that is narrower than the area inside the horseshoe, and the color corresponding to the chromaticity outside the triangle is reproduced. It was impossible.

The present invention solves the above problems and reproduces a color video signal capable of reproducing a wider range of colors than ever before.
An object is to provide a reproducing method and a transmitting method.

[0005]

In order to solve the above-mentioned problems, in the present invention, three types of input of first, second and third corresponding to the display of three respectively different colors necessary for displaying a color image are provided. Calculating means for subjecting the video signal to a matrix operation to generate a fourth video signal corresponding to a new display of a fourth color different from the first, second and the above-mentioned three colors; Display means comprising a plurality of minute pixels which are repeatedly arranged in a predetermined manner to emit light in different colors with luminances corresponding to the second, third and fourth video signals, respectively, and the first, second or 3, polarity determining means for determining whether the input video signal is positive or negative, and the first, second, and third input video signals based on the determination by the polarity determining means, and the first, second, and
And a selection means for selecting and outputting one of the sets of the fourth video signals, and controlling the light emission of each pixel of the display means by the set of the video signals selected and output by the selection means. It was configured to regenerate the signal. Specifically, the pixel corresponding to the first video signal has a red emission color, the pixel corresponding to the second video signal has a green emission color, the pixel corresponding to the third video signal has a blue emission color, and the fourth emission signal has a fourth emission color. The pixel corresponding to the video signal has a green emission color having a chromaticity different from that of the pixel corresponding to the second video signal. That is, the color video signal is reproduced by the display means having a total of four kinds of light emitters G ′ representing green color having different chromaticity from the three primary colors RGB and G.

[0006]

As is well known, the handling of colored light is complicated because it involves not only physical aspects but also psychological or physiological aspects. Red (R) with low visibility near the long wavelength end of the visible range, green (G) with high visibility located near the center of the visible range, blue with low visibility near the short wavelength end of the visible range.
From (B), when a common sense experiment is conducted in which appropriate colors from narrow wavelength regions of the spectrum are taken as the reference primary colors and the three primary colors are mixed by the additive method, any color can be made equal. It has been found that the color obtained by adding the R primary color to the spectral color of the specific wavelength to be matched is equal to the color obtained by adding the G and B primary colors only in the range from about 500 nm to about 450 nm. That is, in the above wavelength range, negative R must be added to G and B. Although there is no difficulty in a color matching experiment using a colorimeter, in practice, negative R is inconvenient to handle, so in CIE, R, G, and B are subjected to primary conversion (matrix conversion) to obtain negative values. It was decided to color by using the amounts X, Y, and Z that did not occur. X includes R, G, and B, but has a relatively large amount of R. There are relatively many G in Y, and Z
Contains few primary colors, but among them, B is relatively large. If X, Y, and Z are selected as the orthogonal coordinate axes, all the colors are in the first quadrant, and the chromaticity is represented by the point where the color vector penetrates the unit plane. The CIE xy chromaticity diagram, which is well known, is obtained by projecting the chromaticity points on the unit plane onto the X and Y planes where Z = 0, which has little influence on the brightness. As is known, existing colors exist only within the horseshoe shape on the CIE xy chromaticity diagram. Conventionally, R and
Although three kinds of pixels selected to represent G and B were used, the color that can be actually reproduced is limited to the inside of the triangle having the chromaticity points of the above three pixels as vertices, and is only within an extremely narrow range. . In the present invention, a negative R is required in the color matching experiment as described above, and in the wavelength range where there are many problems, in addition to green, which is at a position with a slightly longer wavelength on the spectrum of G, and red is slightly mixed, G ' That is, we tried to widen the range of reproducible colors by using green together with G, which has a slightly shorter wavelength on the spectrum and is slightly mixed with blue. That is, conventional R, G,
In addition to the chromaticity points inside the triangle defined by the chromaticity coordinates of the B luminous body, the chromaticity points inside the triangle defined by the chromaticity coordinates of G, G ′, and B can be newly reproduced.

[0007]

The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a color video signal reproducing apparatus (overall reference numeral 7) according to the present invention. Numeral 1 is a matrix circuit (arithmetic means), which performs matrix arithmetic on the inputted R, G, B signals to obtain G, B,
Generate a G'signal. A selector (selection means) 2 selects and outputs one of the set of input R, G, B signals and the set of G, B, G'signals output by the matrix circuit 1.
When the selector 2 outputs R, G, B signals, G '
The output of R is 0, and the output of R is 0 when G, B, and G ′ are output. As a result of the polarity determination circuit 6 determining the polarities of the input signals R, G, and B, the selector 2 determines that the polarity of the R signal is
If positive, the set of R, G, B signals, if negative, G,
A set of B and G'signals is selected and output. The gamma correction circuit 3 is a circuit that performs gamma correction for correcting the input / output characteristic of the display unit 5, which is generally non-linear, so as to be close to linear. Gamma correction is performed by R output from the selector 2,
Gamma correction is performed on each of the G, B signals or the G, B, G'signals. The amplifier 4 amplifies the R, G, B signals or the G, B, G ′ signals gamma-corrected by the gamma correction circuit 3. The display means 5 displays G'for the three primary colors of R, G, and B.
In addition, a cathode ray tube having a total of four types of light-emitting bodies (fluorescent bodies) and a liquid crystal display element in which each pixel is provided with any one of four types of color filters. On the screen of the display means 5, as shown in FIG.
Pixels that emit light of the colors R, G, B, and G ′ are arranged. The arrangement may be arranged in a vertical stripe pattern as shown in FIG. 2A, or may be arranged in a mosaic pattern as shown in FIG. 2B. Next, a color reproduction method in this embodiment will be described. Generally, in a display device having only R, G, and B three primary colors, the range in which color reproduction is possible is as shown in FIG.
R corresponding to the three primary colors on the xy chromaticity diagram of CIE shown in
It is limited to the inside of a triangle with the chromaticity points of G and B as vertices. On the other hand, in the display device according to the present invention, the chromaticity point G ′ is further increased.
It has an illuminant (pixel) corresponding to R, G, B,
It is possible to reproduce the color inside the quadrangle represented by each chromaticity point of G '. In FIG. 3, 8 is the chromaticity point of the R luminous body,
9 is the chromaticity point of the G luminous body, 10 is the chromaticity point of the B luminous body, 11
Represents the chromaticity point of the G'illuminator. R, G, B 3
When using a general playback device having only primary color illuminants,
Only the colors corresponding to the chromaticity points inside the triangle formed by the R, G, and B chromaticity points can be reproduced. On the other hand, in the present invention, since four kinds of light emitters of R, G, B, and G'are used, the chromaticity points inside the quadrangle of the quadrangle consisting of the chromaticity points of R, G, B, and G '. The color corresponding to can be reproduced. Therefore, it is possible to reproduce colors that cannot be reproduced by the conventional display device using the three primary colors. Conventionally, in the case of a color cathode ray tube used for a color television receiver, as a green light emitting phosphor, a deeper one (a value of y on the CIE chromaticity diagram is as large as 0.6 or more) is green. Efforts have been made to discover and develop fluorescent materials that can produce.

Next, a method of generating the R, G, B and G'signals will be described. In the conventional method for reproducing a color video signal using the three primary colors R, G, B, only three types of video signals R, G, B are required. These video signals are generated by an imaging device that outputs R, G, B signals. On the other hand, in the reproducing apparatus of the present invention, R, G, B,
A total of four video signals G'are required. In this case, R,
It is sufficient to prepare signals corresponding to the four primary colors G, B, and G ', but normally, for this purpose, an image pickup device that outputs four types of signals R, G, B, and G'is required. is there. However, it is difficult to realize the spectral characteristics of four types of signals corresponding to this, and it is difficult to manufacture a dedicated image pickup device that outputs R, G, B, and G ′ signals. Therefore, in the present invention, by using R, G, B signals including not only positive polarity R, G, B signals but also negative polarity signals as described below,
An R, G, B, G'signal can be obtained by using a general image pickup device which outputs only the three primary color signals R, G, B. FIG. 4 is a block diagram of an image pickup device for generating R, G, and B signals which are input video signals to the reproducing device of the color video signal of the present invention. In FIG. 4, 12 is a lens, and 13 is a CCD image pickup element (solid-state image pickup plate). CCD 13
The optical image formed by the lens 12 is converted into an electric signal and output as a video signal. The CCD 13 has a pixel (photoelectric conversion unit) array using a filter as shown in FIG. 5 on its light receiving surface. FIG. 5A shows one cycle of a pixel array generally used in a consumer single-panel video camera, where Mg is magenta, G is green, Cy is cyan, and
Ye means a pixel that photoelectrically converts yellow color light. Further, FIG. 5B shows three types of pixels of XYZ arranged in a vertical stripe pattern, and X, Y, and Z are C
It is a pixel having a spectral characteristic that substantially matches the XYZ color matching curve in the IE XYZ color system. The output signal of the CCD 13 is a discrete signal including signals (pixel signals) corresponding to these pixels. The A / D conversion circuit 14 in FIG.
Outputs an output signal of the CCD 13 as a digital signal after A / D conversion. This is because, at present, in general, digitization facilitates storage and calculation and reduces the circuit scale. The matrix circuit 15 includes the A / D conversion circuit 14
Matrix operation is performed on the pixel signals included in the output signal of 1 to generate RGB three-primary-color video signals including negative-polarity components. This video signal is further subjected to various known signal processes, converted into an analog signal by the D / A conversion circuit 17, and generally input to a color video signal reproducing device via a transmission line.

FIG. 6 is a diagram showing ideal spectral distribution characteristics of R, G and B signals. This characteristic is equal to the color-matching curve when color matching is performed using the R, G and B light emitters of the display means 5 in the color video signal reproducing apparatus 7 shown in FIG.
As shown in FIG. 6, the color matching spectral characteristic generally has a negative component. The spectral characteristic including such a negative portion is obtained by performing an appropriate matrix calculation by the matrix circuit 15 shown in FIG. The matrix at this time can be obtained from white on the display means 5 of the reproducing apparatus 7 and chromaticity coordinates in the xy color system of each RGB (pixel) light emitter. For example, the matrix when the image pickup characteristic of the CCD 13 has a spectral characteristic which substantially matches the XYZ color matching curve as shown in FIG. 5B is described in Color Television, page 158, edited by the Japan Broadcasting Corporation. It can be determined by the method that is used. Generally, the CCD 13
If the image pickup characteristic of 1 satisfies the router condition, an ideal RGB spectral distribution characteristic can be obtained by an appropriate matrix calculation. The R, G, and B signals output from the matrix circuit 15 in FIG. 4 are subjected to known processing such as white balance and clamp by the signal processing circuit 16, and then D /
The A conversion circuit 17 converts the analog signal and outputs it.

The input R, G, B video signals in FIG.
It is generated by using the imaging device as described above. Next, R, G, B including the case of negative polarity as described above
A method for obtaining R, G, B, G ′ signals from the signals will be described below. When the input video signal has a positive polarity, the reproduction is performed by the same method as the conventional color reproduction using the three primary colors R, G, and B, as described above. When a negative signal component appears in the R, G, B signals, R, G, including a negative signal,
As described above, the B signal is matrix-converted into G, B, and
Generate a G'signal. Regarding the handling of the negative component in the R, G, B signals, it is usually sufficient to consider only the R signal. The matrix circuit 1 shown in FIG. 1 performs the following matrix calculation.

[0011]

## EQU1 ## C '= (x') to ¹ (x) C However, in the equation 1, C and C'are column vectors each having R, G, B and G, B, G '. . Further, (x) and (x ′) are conversion matrices when C and C ′ are represented by the XYZ color system, and the following relationships of Expression 2 and Expression 3 are established.

[0012]

(2) X = (x) C

[0013]

## EQU00003 ## X = (x ') C' However, the left sides of Equations 2 and 3 are XY in the XYZ color system.
A column vector having each coordinate of Z as a component is shown. Number 1
The relationship is obtained from the fact that the left sides of Equations 2 and 3 are equal. In this way, by using the negative signal of R, it becomes possible to reproduce the colors corresponding to most of the chromaticity points in the triangle GBG ′ on the CIE chromaticity diagram shown in FIG.

As described above, in the color image signal reproducing apparatus according to the present invention, in addition to the three primary colors R, G and B,
Since the green color G ′ having a chromaticity different from that of G is used, the color reproduction range can be expanded as compared with the case where only the three primary colors R, G and B are used. Furthermore, by using the negative polarity signal component of R obtained by the calculation, it is possible to obtain 4 of R, G, B and G ′.
R without using a special imaging device that outputs a signal of a type
G, B, G'signals can be generated.

In the above embodiment, the output R, G, B signals of the image pickup apparatus of FIG. 4 are described as analog signals, but a digital signal is directly output without passing through the D / A conversion circuit 13. Alternatively, digital processing may be performed in the reproducing apparatus shown in FIG. Further, although a single-plate type image pickup device is shown in FIG. 4, a multi-plate type image pickup device using a plurality of CCDs may be used.

Next, an embodiment of a color video signal transmission method according to the present invention will be described with reference to FIG. 18 is
An imaging unit having the configuration shown in FIG. 4 is a reproducing unit having the configuration shown in FIG. 1, 19 is an encoding unit, and 20 is a decoding unit. The encoding means 19 converts the RGB signal into N
Format conversion based on the TSC system and other transmission systems and compression of the amount of information are performed. The decryption means 20 is
The signal encoded by the encoding means 19 is converted to the original R
Play back to GB signal. In the present embodiment, regardless of the content of encoding, as in the embodiment of the color video signal reproducing apparatus shown in FIG. 1, the negative polarity signal components of the RGB signals are also used and transmitted. According to this embodiment, the color reproduction range can be expanded and three kinds of signals of RGB (however, a negative polarity component is partially included, as in the embodiment of the color video signal reproducing apparatus shown in FIG. 1). ) Only, it is possible to reduce the amount of information to be transmitted.

[0017]

As described above, according to the present invention, 3
In addition to the video signals of the primary colors R, G, and B, the video signal of green G ′ having a chromaticity different from that of G is calculated and used. Therefore, only the video signals of the three primary colors R, G, and B are used. Compared with, the color reproduction range of the reproduced video can be expanded.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a color video signal reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a pixel array in a color image display means used in an embodiment of a color image signal reproducing apparatus of the present invention.

FIG. 3 is a diagram illustrating a color reproduction range according to the present invention with a CIE xy chromaticity diagram.

FIG. 4 is a block diagram showing a configuration of an image pickup apparatus for generating an RGB signal including a negative polarity component used as an input video signal to a color video signal reproduction apparatus according to the present invention.

5 is a diagram showing an array of pixels (photoelectric conversion units) corresponding to respective primary colors of the image pickup element used in the image pickup apparatus according to the present invention shown in FIG.

6 is a diagram showing color matching spectral characteristics including negative polarity components of R, G, and B signals output by the image pickup apparatus according to the present invention shown in FIG.

FIG. 7 is an explanatory diagram of a method of transmitting a color video signal according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Matrix circuit, 2 ... Selector, 3 ... Gamma correction circuit, 4 ... Amplifier, 5 ... Display means, 6 ... Polarity determination means, 7 ... Color image signal reproduction apparatus according to the present invention, 8 ... R chromaticity of R light emitter 9 ... G illuminant chromaticity point, 10 ... B illuminant chromaticity point, 11 ... G'illuminator chromaticity point, 12 ... Lens, 13 ... CCD, 14 ... A / D conversion circuit, 15. ... Matrix circuit, 16 ... Signal processing circuit, 17 ... D / A conversion circuit, 18 ... Imaging unit, 19 ... Encoding means, 20 ... Decoding means.

Claims (7)

[Claims] 1. A new first, first, and second input image signals corresponding to three different colors required for displaying a color image are subjected to matrix calculation to obtain new matrix signals. 2nd and 4th corresponding to the display of the 4th color different from the above 3 colors
Calculating means for generating a video signal of
A display means comprising a plurality of minute pixels which are repeatedly arranged in a predetermined manner to emit light of different colors with luminances corresponding to the third and fourth video signals, respectively, and display means, and the first, second or third display means. Polarity determining means for determining whether the input video signal is positive or negative, and the first, second, and third input video signals based on the determination by the polarity determining means, and the first, second, and fourth output by the computing means. A color video signal is reproduced by controlling the light emission of each pixel of the display means by means of the video signal set selected and output by the selection means. An apparatus for reproducing a color video signal, characterized in that 2. A pixel corresponding to a first video signal is red and a pixel corresponding to a second
The pixel corresponding to the video signal of 3 has a green emission color, the pixel corresponding to the third video signal has a blue emission color, and the pixel corresponding to the fourth video signal has a color different from the pixel corresponding to the second video signal. 2. The color video signal reproducing apparatus according to claim 1, wherein the color video signals have different green emission colors. 3. The first, second, third, and the like input to the display means
3. A color video signal reproducing apparatus according to claim 1, further comprising means for performing gamma correction on each of the fourth video signals. 4. A new first, first and second matrix operation is performed on three types of input image signals of first, second and third corresponding to display of respectively different three colors necessary for displaying a color image. 2nd and 4th corresponding to the display of the 4th color different from the above 3 colors
Image signal is generated, the polarity of the first, second, or third input image signal is determined, and the first, second, or third input image selected according to the result is determined. The first, second, third, and fourth signals are repeatedly arranged in a predetermined manner by one of the signal set or the first, second, and fourth video signal sets generated by the calculation. Color that reproduces a color image by controlling the light emission of each pixel of the reproduction display screen that is composed of a group of minute pixels that emit different colors with brightnesses corresponding to the respective video signals Video signal reproduction method. 5. A first video signal of a red light emitting pixel, a second video signal of a green light emitting pixel, a third video signal of a blue light emitting pixel, and a fourth video signal of a second video signal. 5. The method for reproducing a color video signal according to claim 4, wherein the light emission of a green light emitting pixel having a chromaticity different from that of the pixel corresponding to is controlled. 6. The color according to claim 4, wherein the set of the first, second and third input video signals may include a negative input signal component in some cases. Video signal reproduction method. 7. A method of transmitting color video signals corresponding to red, green, and blue, respectively, wherein transmission is possible regardless of whether positive or negative signal components are mixed. Color video signal transmission method.