JP2684426B2 - Color video system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color image system that improves color reproducibility by expanding a color reproduction range.

[Conventional technology]

Conventionally, a color image system generates a color signal representing information of the three primary colors by spectrally and photoelectrically converting each part of an optical image of a subject into three primary colors of red, blue, and green by a color imaging device (color camera or the like), The color signals are subjected to correction (for example, γ correction) in consideration of the non-linearity of a receiver, which will be described later, to form image receiving three primary color signals S _R , S _G , S _B , while a tricolor tube or a trinitron tube is formed. The color reproduction of the subject image is performed by controlling the electron beam of the image receiving device using a three-color picture tube such as the above by the image receiving three primary color signals S _R , S _G , and S _B.

The color gamut of the image receiver is determined by the chromaticity of the three primary colors of the three-color picture tube (hereinafter referred to as the image reception three primary colors).
This also defines the spectral characteristics that the color image pickup device should have.

Therefore, as shown in the chromaticity diagram of FIG. 6, the colors of the light emitted by the red, green, and blue phosphor dots arranged on the phosphor screen of the three-color picture tube, that is, the three primary colors of the picture are relative to red ( R), (G) for green, and (B) for blue, the inside of the triangle formed by these chromaticity points (indicated by a solid triangle in the figure) is on the image receiving screen. The chromaticity range can be reproduced with.

Furthermore, the range of this triangle is the ideal maximum chromaticity range, and since there is a limit in practice, the inside of the triangle, for example, shown by the dotted line, is the actual chromaticity range. The vertices of the triangle shown by the dotted line in the figure are the actual chromaticity points of red (r), green (g), and blue (b).

Thus, although the actual chromaticity range is narrower than the ideal chromaticity range (hereinafter referred to as the ideal chromaticity range), it is important to expand this actual chromaticity range to improve color reproducibility. Has become a problem.

Conventionally, as a method for expanding such a color reproduction range, a method proposed by Epstein, that is, in view of the fact that the human eye has a negative spectral characteristic, A method for expanding the chromaticity range by adding the three primary colors of the image is known.

The principle of this method will be described based on the chromaticity diagram of FIG. 6 and the color matching function of FIG. In FIG. 7, the alternate long and short dash line F _R is the spectral characteristic of the red of the human eye, the broken line F _G is the spectral characteristic of the green of the human eye, and the dotted line F _B is the spectral characteristic of the blue of the human eye. (Hereinafter referred to as ideal imaging characteristics) is the negative sensitivity of red (indicated by β) in the wavelength range of about 460 nm to 530 nm for red, and about 400 nm to 460 nm and about 64 for green.
Green negative sensitivity (denoted by α and δ) in the wavelength range of 0ne to 680nm,
With respect to blue, the negative sensitivity (γ of blue) in the wavelength range of approximately 530 nm to 620 nm
Indicated by).

However, with a three-color picture tube, the amount of light emission of the three primary colors cannot be made negative, so by removing these negative sensitivity parts from the lobe of the nearest positive part of the ideal imaging characteristics,
Pseudo image receiving three primary color signals S including the negative sensitivity _{'R, S' G, S} '
Forming a _B, and a method for emitting the phosphor dots of three colors picture tube in accordance with these signals _{S 'R, S' G,} S 'B.

The solid line F _'R is an imaging characteristic related to red after correction set by this method, the solid line F' in FIG. 7 Green an imaging characteristics after _G is corrected, the solid line F _'B in the imaging characteristics for the blue after correction Yes, each wavelength range is narrowed by removing the lobe of the characteristic for each color.

To perform the actual processing based on this method, for example,
First, the color image pickup device of the color image pickup device picks up an optical image of an object to generate conventional red (R), green (G), and blue (B) color signals S _R , S _G , and S _B. Therefore, the image pickup characteristic of the color image pickup device at this time is a positive response portion excluding the negative sensitivity portion of the characteristic curves F _R , F _G , and F _B before correction shown in FIG. Corresponding color signals will be obtained.

Next, in the process circuit in the color image pickup device, the matrix calculation processing of the following equation (1) is performed to approximately form the color signal including the negative sensitivity portion of the image pickup characteristic.

It should be noted that the coefficient of the above equation (1) is a coefficient for comprehensive correction together with the negative sensitivity portion in view of the fact that there is an error in the positive portion of the image pickup characteristic. characteristic curve _{F 'R, F'} of Figure 7 described above G, an F _'B.

Then, the image receiving three primary color signals S _'R, S' corrected by the formula (1) _G, by causing the phosphor to emit light dots of the three color picture tube on the basis of the S _'B, color in consideration of the portion of the negative sensitivity Reproduction can be simulated.

If the chromaticity range in the case where this correction processing is not performed is within the range of the triangle indicated by the dotted line in FIG. 6, by performing the correction related to this negative sensitivity, ideal imaging is performed using this dotted line triangle. It becomes possible to reproduce an intermediate color between the characteristics, which is effective in improving color reproducibility.

[Problems to be solved by the invention]

However, in a color image system to which such a conventional method of expanding the chromaticity range is applied, since it is based on the approximation processing, its effect is naturally limited, and a significant improvement in characteristics can be obtained. Can not.

The present invention has been made in view of these problems, and an object thereof is to provide a color image system capable of improving color reproducibility based on a principle different from the conventional one.

[Means for solving the problem]

For such an object, the present invention provides an image receiver that forms fine color-developing portions for setting chromaticity points in a predetermined array on a display surface, and performs color reproduction by scanning these color-developing portions at predetermined timing. In the provided color image system, each color forming portion formed on the display surface of the receiver is provided with a primary color of red (R), a primary color of green (G), a primary color of blue (B) and a wavelength of a red negative sensitivity portion. A total of four fourth color-developing portions having color-developing characteristics in a range
A large number of sets are arranged with one color forming part as one set, and color reproduction is performed by additive color mixing of light emitted from these four kinds of color forming parts.

As one embodiment, an image receiver is used in which the color-developing portion is displayed by a picture tube using phosphor dots.

That is, in a picture tube that reproduces color by reproducing and scanning a phosphor dot that sets a chromaticity point with an electron beam of an electron gun, each phosphor dot formed on the phosphor screen of the picture tube is a primary color Red (R), primary green (G), primary blue (B)
A large number of sets of four dots of the fourth phosphor dot having the emission characteristic in the wavelength range of the negative sensitivity region of red and red are arranged, and an electron beam from the electron gun is applied to these four kinds of phosphor dots. Color reproduction is performed by additive color mixing that is stimulated by irradiation.

Further, four electron guns for emitting these phosphor dots may be provided corresponding to each, or scanning control may be performed so that four types of phosphor dots are scanned by the conventional three electron guns. It may be performed. In short, the number of electron guns is arbitrary.

Further, as another embodiment of the present invention, an image receiver including a color liquid crystal display in which a large number of four types of color forming portions corresponding to the above four types of luminous body dots are arranged as one set may be applied.

Furthermore, the principle of the present invention will be described with reference to FIG.
The characteristic curve f _R in the figure shows the characteristic of red (R) in the three primary colors of the image received, and the fine color developing portion having the color developing characteristics in such a wavelength range is used as the first color developing portion, and the characteristic curve f _G is Characteristic of green (G) among the three image-receiving primary colors is shown, and a color-developing portion having such a color-developing characteristic in the wavelength range is used as a second color-developing portion, and a characteristic curve f _B is the color of green (G) among the image-receiving three primary colors. The color-developing portion having the color-developing characteristic in such a wavelength range is defined as the third color-developing portion, and these characteristic curves f _R , f _G , and f _B are ideal imaging characteristics F _R , F shown in FIG. _It has the characteristics excluding the negative sensitivity parts of _G and F _B. Furthermore, the negative sensitivity part of FIG. 6 (about 46 shown by the shaded range β)
A fourth color development part having a positive color development characteristic (shown by the curve f _RG in FIG. 1) corresponding to a response in the wavelength range of 0 nm to about 530 nm) is added, and the light emitted by these four types of color development parts is added. Color is reproduced by mixing.

[Action]

In a color image system that reproduces the color of an object with a receiver having such a configuration, as shown in the chromaticity diagram of FIG. 2, the outside connecting the conventional chromaticity points (G) and (B). Since the fourth chromaticity point (G _R ) by the third color-developing unit is set to, the portion of the chromaticity range surrounded by the chromaticity points (G), (B) and (G _R ) Can be expanded. As a result, it is possible to greatly contribute to the improvement of the color reproducibility of the intermediate color between blue (B) and green (G), which is particularly excellent in the color resolution of human eyes.

In FIG. 2, the principle of the present invention has been described in an ideal case. However, in practice, the chromaticity points (R), (G), shown in FIG.
A (G _R) and being limited to the inner narrow chromaticity range (B). However, since the actual chromaticity range is also expanded similarly to this ideal chromaticity range, the color reproducibility is significantly improved as compared with the conventional one.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

First, the overall configuration of the color image system including the image pickup device and the image receiving device will be described with reference to FIG.

In the figure, the area indicated by the dotted line A is the image pickup apparatus, and the area indicated by the dotted line B is the image receiving apparatus. Reference numeral 1 is an image pickup optical system, and 2 is a solid-state image pickup device provided behind the image pickup optical system 1. is there.

As the solid-state imaging device 2, for example, a charge-coupled solid-state imaging device (CCD) configured as shown in FIG. 4 is applied,
In the light receiving element group formed in the light receiving region 2a, which has 1000 rows in the vertical scanning direction and 800 columns in the horizontal scanning direction for a total of 800,000 pixels, the red (f _R ) and green ( Four types of minute color filters R, G, B, and G _R for generating signal charges of f _G ), blue (f _B ), and fourth color (f _RG ) are arranged as a set. The optical filter having such spectral characteristics is formed by dyeing a fine pattern such as casein or gelatin with an appropriate dye.

Reference numerals 2b and 2c denote horizontal charge transfer paths for reading out signal charges transferred from the light receiving region 2a in each horizontal blanking period in synchronization with the timing of horizontal scanning, and are for simultaneously reading out signal charges for two rows as one set. In addition, a pair of horizontal charge transfer paths 2a and 2b are provided.

Such signal reading is performed in synchronization with the vertical drive signals φ _{V1 to} φ _V4 for vertical transfer and the horizontal drive signals φ _H1 and φ _H2 for horizontal transfer output from the drive circuit 3 of FIG. . That is, in order to output the signal charges generated from the light receiving elements of 1000 rows in the light receiving region 2a in conformity with 525 TV lines of the standard television system, the signal charges are transferred as a set of two rows during the horizontal blanking period. The horizontal charge transfer paths 2b and 2c are read out in chronological order according to the horizontal drive signals φ _H1 and φ _H2 that are synchronized with the dot-sequential scanning timing during the horizontal scanning period. .
The first row is the horizontal charge transfer path 2b, i.e. _{R, G R, R, G} R, R,
The signal charges generated in the light receiving element provided with the filter G _R , ... Are transferred, and the horizontal charge transfer path 2c is in the second row, that is, G, B, G, B, G, B ,. The signal charge generated in the light receiving element provided with the filter is transferred.

Red (R) color signal S _R output from the horizontal charge transfer path 2b
When the sample-hold circuit 4a for the color signal S _GR fourth color (G _R), the color signal S of the color signal S _G and blue green output from the horizontal charge transfer path 2c (G) _(B) B In the sample hold circuit 4b, the sample hold process of the correlated double sampling method is performed in accordance with the sample hold signal supplied from the timing circuit 5 (synchronized with the dot sequential scanning timing), and the multiplexer circuit 4c, After being separated into individual color signals S _R , S _GR , S _G , and S _B by 4d, they are transferred to the process circuit 4e.

In process circuit 4e, color signals of red performing the process such as γ correction, white balance adjustment S _'R, the color signal S relating to the fourth color' _GR, green color signal S _'G, the color signal S blue' _B
Is output.

Returning to FIG. 3 for further explanation, 6 is the signal processing circuit 4.
Output time series color signals S ′ _R , S ′ _GR ,
A modulation circuit that performs appropriate modulation such as FM modulation on S ′ _G and S ′ _B , and the modulation signal is recorded on a magnetic recording medium or the like in the recording circuit 7.

7 is an encoder, the color signal _{S 'R, S' GR,} S '
_G, and outputs the converted transmission signal capable of transmitting S _'B.

Next, the configuration of the image receiving device B will be described. 8 receives the signal transmitted from the encoder 7, the original color signal _{S 'R, S' GR,} S 'G, S' is a decoder back to _B, for controlling the electron gun of the four-color image pickup tube Picture tube circuit 9
Output to Then, in the picture tube circuit 9, by performing reproduction scanning and brightness adjustment in synchronization with the reading scanning timing of the solid-state imaging device 2 in the imaging device A, the electron beam generated by the electron gun is applied to the phosphor dots to color them. Reproduce.

10 is a reproducing circuit, the original color signals S demodulates the modulated signal recorded on the recording medium by the recording circuit _{7 'R, S' GR,} S '
_G, returned to S _'B, and supplies to the CRT circuit 9 via the switching circuit (not shown).

Figure 5 shows the structure of four-color picture tube for performing color reproduction in accordance with a signal from the kinescope circuit 9, color signals S _{'R,
S 'GR,} S' G, includes four electron guns corresponding to S _'B. Further, when the phosphor screen receiving an electron beam from the electron gun, the red (R), blue (B), green (G) and the fourth color (G _R) scratch four phosphor dots that emit A large number of sets are formed in a matrix shape in the vertical and horizontal scanning directions, and four electron beams emitted from four electron guns based on predetermined scanning control are made into phosphor dots through a shadow mask. Made to illuminate.

As described above, according to this embodiment, the fourth phosphor having the emission characteristics in the wavelength range of the red phosphor dot, the green phosphor dot, the blue phosphor dot, and the red negative sensitivity portion. Applying a four-color picture tube in which a total of four types of phosphor dots are formed on the phosphor screen in a predetermined array, and these phosphor dots are scanned with an electron beam to perform color reproduction by additive color mixing. Therefore, as shown in FIG. 2, the chromaticity range can be expanded as compared with the conventional three-color picture tube. In particular, since the chromaticity range of the intermediate color between green and blue can be expanded, it can be adapted to the color sensitivity of the human eye. In addition, since it is not necessary to perform the approximation processing of the negative sensitivity portion proposed by Mr. Epstein, the system configuration can be simplified.

In this embodiment, four electron guns are used for the replay scanning, but the number of electron guns may be arbitrary, and the point is to provide a control circuit for replay scanning the phosphor dots according to the standard television system or the like. It may be configured.

Further, although the picture tube using the electron beam has been described in this embodiment, a picture receiving apparatus using a liquid crystal device may be used. That is, a portion corresponding to a phosphor dot is used as a fine color filter that emits light of the above four colors, and the light transmission amount of an electrode corresponding to a pixel of a liquid crystal device provided between the color filter and the backlight is represented by a signal S. ' _R , _S'GR ,
S _{'G, S'} may be controlled on the basis of the _B.

〔The invention's effect〕

As described above, according to the present invention, the total of the fourth color forming portion having the color forming characteristics in the wavelength ranges of the fine red color forming portion, the green color forming portion, the blue color forming portion, and the red negative sensitivity portion is used. Since we applied an image receiver in which four types of color-developing parts were formed in a predetermined arrangement on the display surface and these color-developing parts were reproduced and scanned to reproduce colors by additive color mixing, the chromaticity range was expanded and The reproducibility can be greatly improved.

[Brief description of the drawings]

1 and 2 are explanatory views of the principle of the present invention; FIG. 3 is an explanatory view of an embodiment of one embodiment; FIG. 4 is an explanatory view of detailed structure showing a part of FIG. 3 in detail; FIG. 6 is a structural explanatory view for explaining a schematic structure of a receiver; FIG. 6 is a partial structural explanatory view showing an enlarged structure of a phosphor screen in FIG. 5; FIG. 7 and FIG. 8 are conventional color reproductions. It is explanatory drawing explaining a principle. Reference numeral in the figure: 1; imaging optical system 2; charge-coupled solid-state imaging device 2a; light receiving sections 2b, 2b; horizontal charge transfer path 3; drive circuit 4; signal processing circuits 4a, 4b; sample hold circuits 4c, 4d; Multiplexer 4e; process circuit 5; timing circuit; 7; encoder 8; decoder 9; picture tube circuit

Claims (1)

(57) [Claims] 1. A color image system including a receiver in which a plurality of fine color-developing portions for setting chromaticity points are arranged on a display surface, and these color-developing portions are scanned at a predetermined timing to reproduce a color. Each color forming portion formed on the display surface of the receiver has color developing characteristics in a wavelength range of a primary color red (R), a primary color green (G), a primary color blue (B) and a red negative sensitivity portion. 4th color development part in total
A color image system characterized in that a large number of sets are arranged with one color forming part as one set, and color is reproduced by additive color mixing of light emitted from these four kinds of color forming parts.