JPS59168790A - Color image pickup device - Google Patents

Abstract

PURPOSE:To obtain a solid-state image pickup device having excellent picture quality and less generation of a chrominance signal because of the error of vertical correlation by using a video signal comprising three scanning lines so as to obtain a red signal, a blue signal and a luminance signal. CONSTITUTION:A transparent signal W and a green signal G are obtained from the n-th scanning line of a solid-state image pickup element and a cyan CY and a yellow signal Ye are obtained alternately from the (n+1)-th scanning line at each other picture element. In applying 1H delay and 2H delay to the output signal of the solid-state image pickup element by using two 1H delay lines, when the [n+1(H)]th output signal is obtained, the signal of the n(H)- the [n-(H)] is obtained. In forming an average value by adding respectively the [n-1(H)] and the [n+1(H)] CY signals by 1/2 each, the signal is formed by interpolating the CY signal of the W signal at the n(H) being a reference. Further, the red R signal is obtained by operating the CY signal and the W signal thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color imaging device using a charge transfer imaging device (hereinafter abbreviated as CCD imaging device).

The trick is to obtain a color television signal using one image sensor.
A known method is to place a filter at a position that connects the real image of the subject, spatially modulate the red and blue signals, frequency multiplex them with the green signal, and extract them from the image sensor. In this method, the output of the image sensor is passed through a low-pass filter to obtain a luminance signal.
- Since the red signal and the blue signal are multiplexed and included in the output of the image sensor as a carrier wave component (hereinafter abbreviated as modulation component) determined by the frequency of spatial modulation, they are extracted using a bandpass filter, and the extracted modulation A red signal and a green signal are further separated from the components and obtained.

Conventionally, as a method for separating red and blue signals from modulation components, two kinds of methods are used to separate red and blue signals from two adjacent scanning lines so that the red modulation components and blue modulation components contained in two adjacent scanning lines have a frequency interleaving relationship. An array of color filters is selected, and the modulation components extracted by the bandpass filter are delayed by a delay line corresponding to one horizontal scan (hereinafter abbreviated as IH delay line), and frequency interleaving is performed from the modulation components of the two scanning lines. A method is known in which the red modulation component and the back modulation component are separated using the following relationship, and then each modulation component is subjected to &H to obtain a red signal and a blue signal. Conventionally, a glass delay line is generally used as an IH delay line. By the way, this glass delay line converts the input electrical signal into an ultrasonic wave using a piezoelectric element, propagates this ultrasonic wave through the glass, and then converts the ultrasonic wave into an electrical signal again using a piezoelectric element on the output side to delay the signal. The propagation time of the ultrasonic waves in the glass is set to the time equivalent to one horizontal scan. In a glass delay line, when this ultrasonic wave propagates through the glass, it causes unnecessary reflections, and the output signal includes signals (spurious signals) caused by this unnecessary reflection, which affects the image quality of the red and blue signals. There was a drawback that the value decreased.

In addition, since the red signal and the blue signal are obtained from the modulation components of two scanning lines, the phase with the luminance signal in the vertical direction of the image is V2 of the scanning line.
If two color difference signals, R-Y signal and B-Y signal, are formed with this out-of-phase signal, a false color difference signal will be formed in the vertical contour of the image, resulting in false colors. and a phenomenon in which false red signals and blue signals occur due to vertical correlation errors in vertical contour areas with no vertical correlation in the image.
This method has two essential drawbacks. In order to prevent the image quality from deteriorating due to these two drawbacks, the low-frequency component of the luminance signal for forming the color difference signal is formed by the luminance signal of two scanning lines, and the red signal, the blue signal, and the vertical It is necessary to obtain the low-frequency components of the luminance signal whose phases match in the direction, and at the same time form a vertical contour signal, and use this vertical contour signal to suppress false red and blue signals caused by vertical correlation errors. However, conventionally, to obtain the luminance signals of two scanning lines, separate I
The luminance signal must be delayed by IH using an H delay line, which has the disadvantage of complicating the device.

In order to solve these conventional drawbacks, the same applicant as the present application proposed in Japanese Patent Application No. 57-61904 that video signals corresponding to all color light and green light components are obtained alternately in the scanning line direction.
Video signals corresponding to cyan light and yellow light components are obtained alternately in the scanning line direction, and video signals corresponding to all color light and green light components and video signals corresponding to cyan light and yellow light components are scanned. a solid-state image sensor configured to obtain a signal sequentially for each line; an IH delay line that delays the output signal of the solid-state image sensor by a time corresponding to one horizontal scanning line; a first output signal that is not delayed; The second delayed by the IH delay line of
A switching circuit that switches two output signals for each scanning line to create a video signal corresponding to continuous all-color light and green light components and a video signal corresponding to continuous cyan light and yellow light components. and a separation circuit that separates four video signals corresponding to components of all-color light, green light, cyan light, and yellow light from the two consecutive video signals, and a separation circuit that separates the separated all-color light and A color imaging device has been proposed that includes at least a matrix circuit that forms video signals corresponding to red light and blue light components from four video signals corresponding to green light, cyan light, and yellow light components. However, it became clear that this previously proposed color imaging device had a drawback in that large false red and green signals were generated due to vertical correlation errors, and it was necessary to suppress these false red and green signals using vertical contour signals. In addition, although a good luminance signal of 8/N can be obtained, the red and blue signals are poor at S/', which deteriorates the image quality, and furthermore, only a -th order differential type vertical contour signal can be obtained. The problem has become clear that it is not possible to increase the resolution because this causes a phase shift equivalent to the V2 scanning line in the vertical direction with the low-frequency luminance signal, resulting in unnatural edge enhancement.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an improved color imaging device with a simple configuration and no deterioration in image quality.

According to the present invention, video signals corresponding to all color light and green light components are obtained alternately in the scanning line direction, and video signals corresponding to cyan color light and yellow light components are obtained alternately in the scanning line direction. and a solid-state imaging device configured to obtain a video signal corresponding to all color light and green light components and a video signal corresponding to diagonal color light and yellow light components line-sequentially for each scanning line, and the solid-state imaging device a first delay line that delays the output signal of the output signal by a time corresponding to one horizontal scanning period; and a second delay line that delays the output signal of the output signal by a time corresponding to two horizontal scanning periods; The signal obtained by adding the third output signal delayed by the second delay line and the second output signal delayed by the first delay line are switched for each scanning line to produce continuous full-color light and green light. Create a video signal corresponding to one component of , and a video signal corresponding to continuous cyan light and yellow light components, and from these two continuous video signals, create a video signal corresponding to all color light, green light, cyan light, and yellow light components. At least a separation circuit that separates each of the four video signals, and a multiplex circuit that forms video signals corresponding to red light and blue light components from the four separated video signals. A color imaging device is obtained.

The present invention will be explained in detail below using the drawings.

FIG. 1 shows an example of a pixel arrangement according to the present invention.

As shown in Figure 2, this pixel array consists of transparent (5) and cyan (Cy) pixels that are tilted at an angle such that the phase changes by 180° for each scanning line with respect to the vertical direction of the image. The red signal is spatially modulated by the filter, and similarly transparent and yellow (
The blue signal is spatially modulated by a filter consisting of the following: (Ye). In Figures 1 and 2, the pixel 11 is transparent (W), and the pixel 12 has cyan (Cy) and yellow (Ye) overlapping each other, so the line that can pass through both filters (G) ). code 13
is cyan (Cy), and code 14 is yellow (ye).

In Figure 1, from the n-th (n: 1, 3, 5...) scanning line, transparent (9) and green CG) are shown, and from the n+1-th scanning line, cyan (Cy) and yellow (Ye) are shown. ) are obtained alternately for every other pixel.

In the color imaging device proposed in the above-mentioned Japanese Patent Application No. 57-061904, the output signal of the solid-state imaging device is delayed by an IH delay line having a delay time equivalent to one horizontal scanning period, and the nth (H ) is obtained, the n-1st (H) output signal is obtained from the IH delay line, and these two output signals are switched every scanning line □ to produce continuous W and green (G) signals. A signal of W, green (G), cyan (Cy), and yellow (Ye) is generated using four gate circuits. After separating the signals, red (B) is extracted from these four signals using a multiplex circuit.
) and blue (B) video signals are separated.

In the separation method of red (R) and blue (B) video signals as described above, the second (nth) (H) and n-1st (H)
Since two signals are used, it is necessary that the two signals have a correlation in the vertical direction. In other words, in Fig. 1, W1 and green (G) of the four signals W1, green (G), cyan (CY), and yellow (Ye) necessary to separate red (R) and blue (B) video signals. ) is the standard for the nth (H)
Considering the case where the other two colors, cyan (Cy) and yellow (Ye) are obtained from the scanning line of
) will be used.

Therefore, these two output signals of cyan (Cy) and yellow (Ye) are the video signals corresponding to the cyan (Cy) and yellow (Ye) components at the position of the reference nth (H) scanning line. Not the same. Therefore, if the brightness, hue, and saturation differ between the positions of the nth (H) scanning line and the n-1st (H) scanning line, there is a vertical correlation between the red (R) and blue (B) video signals. A false color signal is generated due to the error. In conventional color imaging devices, this false signal occurs significantly even with slight changes in brightness, hue, and saturation in the vertical direction. Therefore, it is necessary to use a method to suppress false signals by optically blurring the subject image.

The drawback of conventional color imaging devices is that video signals corresponding to the same color light component can only be obtained intermittently, such as only in odd-numbered or even-numbered scanning lines.

In this way, when video signals corresponding to the same color light component are generated intermittently every other scanning line, such as only in odd numbered or even numbered scanning lines, for example, Japanese Patent Laid-Open No. 57-11119
As described in No. 3, there is a known method of adding and using two signals adjacent to the missing scanning line, but in an imaging device using a complementary color filter like the present invention, the signals are separated and used. The red (R) and blue (B) video signals that you are trying to obtain are all frequency-multiplexed and included in each scanning line, so simply delaying and averaging the video signals will not produce the red (R)
and blue (B) video signals cannot be obtained.

Next, FIG. 3 is a schematic diagram showing the principle of a color imaging device according to the present invention, which eliminates the above-mentioned conventional drawbacks. Figure 3 (a
) and (b) show the red (R) signal separation method, and FIGS. 3(C) and (d) show the blue (B) signal separation method. In the figure, when the output signal of the solid-state image sensor is subjected to IH delay and 2H delay using two IH delay lines, the output signal from the solid-state image sensor is
(H) output signal is obtained, the IH-delayed signal is the n-th (H), and the 2H-delayed signal is the n-l (H).
signal is obtained. Taking FIG. 3(a) as an example, the (n-1)th (H) cyan (cy') signal and the (n+1)th (H)
) of cyan (Cy) signals by 1/2 each to create an average value, W at the n-th (H) which becomes the reference
It can be obtained by interpolating the cyan (Cy') signal at the signal position.

The cyan (Cy') signal obtained by this interpolation is the n-i (
■It is the average value of 1) and the nth
A value almost equal to cyan (Cy) + i in (H) is obtained. A red (R) signal can be obtained by calculating the obtained cyan (Cy') signal and the W signal. Figure 3 (
The operations are exactly the same for b) to (d).

According to the color signal separation method of the color imaging device of the present invention described above, when the vertical correlation is quite strong, false color signals due to vertical correlation errors are hardly generated. Further, even when there is no vertical correlation at all, since the signals of the two scanning lines are averaged, the vertical correlation error is greatly reduced. As is well known, the vertical correlation is quite strong in common subjects, so the color signal separation method of the present invention significantly reduces false color signals compared to the conventional method, which is necessary in conventional color imaging devices. Better image quality than before can be obtained without using a method of suppressing false color signals using vertical contour signals.

Furthermore, as is clear from the above explanation, since the red (R) signal and blue (B) signal are separated from the video signal for three scanning lines, the intensity of the obtained color signal is improved compared to the conventional method, and this improves the image quality. becomes even better.

FIG. 4 is a schematic diagram showing an embodiment of the present invention.

In the figure, a solid-state image sensor 1 combined with a color filter
5 output (hereinafter abbreviated as OH signal) is an IH delay line]
6, the time corresponding to one scanning line is delayed.

IH delayed signal (hereinafter abbreviated as IH multiplied signal) OH
As mentioned above, the signal, IH double signal, and 2H signal are
The multiplied signal is used as a reference signal, and the missing video signal at the scanning line position of the reference signal is interpolated from the OH signal and 2H signal that are vertically adjacent to this reference signal ζ. In other words, in FIG. 4, the OH signal and the 2H signal
8 = 72 (OH signal) + 1. '2 (2H signal)
Then, an interpolated signal for the missing scanning line position is obtained.

Next, the IH multiplication signal and the interpolation signal mentioned above are converted to the switch 1 for each scanning line.
You can switch between 9 and 20. The output of switch 19 is IH
1 signal → interpolation signal → IH signal → ..., the output of the switch 20 is interpolation signal → 1) (signal → interpolation signal → ..., etc. In FIG. 1, the reference scanning line is n (H) Therefore, the output of switch 19 is continuous W for each scanning line.
Similarly, the output of the switch 20 becomes a continuous cyan (CY) and yellow ('Ye) signal. These two signals are applied to four gate circuits 21-24. A gate signal 25 is applied to gate circuits 21 and 24, a W signal is separated in gate circuit 2, and a cyan (Cy) signal is separated in gate circuit 24. Similarly, gate circuit 22
and 23 are applied with a gate signal 26, and the gate circuit 22 separates a green (G) signal, and the gate circuit n separates a yellow (Ye) signal.

The four separated signals are subjected to calculations expressed by the following two equations to separate a red (R) signal and a blue (B) signal.

R = W + Ye-o-Cy - (1) B = W + Cy-G-Ye - (2) Note that the four signals sent to the arithmetic circuit for calculating equations (1) and (2) are Before being added to the circuit, the signal is subjected to amplitude limiting processing in limiters 27 to 30.

Limiter 27z 30 is based on the aforementioned patent application No. 57-0619.
As stated in No. 04, the maximum amplitude of these four signals is limited so that the red (R) signal and blue (B) signal do not become zero even when the output of the solid-state image sensor 15 is saturated. There is. That is, in equations (1) and (2) for obtaining the red (R) signal and the blue (B) signal, when the output of the solid-state image sensor 15 reaches a saturated state and becomes W2G:Ye:'CY, (1)
An error occurs in the calculation so that both the calculation results of the equation and the equation (2) become zero, but the limiters 27 to 30 prevent this error in the calculation, and the four signals are adjusted so that W > Ye, Cy)G. The amplitude is limited so that the red (R) signal and the blue (B) signal do not become zero even when the output of the solid-state image sensor 15 is saturated.

The outputs of the limiters 27 to 30 are then applied to arithmetic circuits 31 and 32, and the above-mentioned equations (1) and (2) are calculated to obtain a red (R) signal and a blue (B) signal. Note that this calculation circuit can optimize color reproducibility by multiplying the four signals of equations (1) and (2) by coefficients to perform the calculation of the following equation. Extremely superior color reproducibility can be obtained compared to a frequency separation type color imaging device using a conventional image pickup tube in which coefficient manipulation cannot be performed.

R=W+aYe −bG −cCy −(3iB
=W+dCy-eG-fYe-(4) Each coefficient is determined to a value that optimizes color reproducibility based on the imaging characteristics of the solid-state image sensor 15 and the spectral characteristics of the color filter.

The red (auxiliary signal and blue (B) signal are then passed through a low-pass filter 33.
and 34 are limited to the band necessary to form a color difference signal.

On the other hand, the OH signal and the IH multiplied signal 2H signal are applied to low-pass filters 35 to 37, respectively, to obtain a luminance signal from which the clock component and modulation component have been removed. The obtained OH luminance signal (Y (oii) signal), IH luminance signal (Y (IH) signal), and 2H luminance signal (Y (2M) signal) are the red (R) signal and blue (B) signal. It is also added to the process encoder circuit side.

The process encoder circuit 38 uses the Y(0)1) signal, the Y(IH) signal, and the Y(2H) signal to form a well-known 2H type contour correction signal. That is, Y(OH
) signal, Y (IH) signal, and Y (2H) signal in the ratio of the following formula, a broadband luminance signal (Y (W ) signal is formed.

Y(W) signal 2% (Y(OH) signal) 10% (Y(H()
signal)+3(Y(2H) signal) This Y(W) signal is second-order differentiated in the horizontal direction to obtain a horizontal contour correction signal. A vertical contour signal in the vertical direction can be obtained by adding and subtracting the Y(OH) signal, the Y(IH) signal, and the y(2H) signal at the ratio of the following equation.

Vertical contour signal” -3A (Y(OH) signal) + Y(11
() signal 3A (Y(2H) signal) Since this vertical contour signal is a quadratic differential contour signal formed using the luminance signals of three scanning lines, it is possible to perform natural contour forcing, and The resolution is improved compared to color imaging devices. These two contour signals are subjected to horizontal and vertical contour enhancement in a known manner to improve resolution.

Next, the low frequency component of the Y(W) signal is used as a narrowband luminance signal (Y(L) signal) for forming a color difference signal. As described above, since the Y (W) signal, the red (R) signal, and the blue (B) signal have the same phase in the vertical direction, false color difference signals are not generated at the vertical contour portion.

Process encoder circuit 38 is red (1%) as described above.
) signal, blue (B) signal, Y (■・) signal, Y (L) signal, horizontal and vertical contour signals, respectively, and undergoes processing such as comma correction, white clipping, blanking, black clipping, flanking mixing, etc. After that, a composite color video signal is formed.

As explained above with reference to the drawings (this invention uses video signals of three scanning lines to obtain a red (R) signal, a blue (B) signal, and a luminance signal, according to the invention, vertical correlation error Therefore, it is possible to realize a solid-state imaging device with extremely good image quality, in which the generation of formal color signals is extremely small.

In the above explanation, the yellow (Ye) filter was arranged vertically and the cyan (Cy) filter was arranged diagonally as shown in Figure 2, but this is because the yellow (Ye) filter and cyan (Cy) filter are arranged in reverse. Even if they are replaced, it is exactly the same.

[Brief Description of the Drawings] Figs. 1 and 2 are schematic diagrams showing the arrangement of color filters used in the color imaging device of the present invention, Fig. 3 is a schematic diagram showing the principle of the present invention, and Fig. 4 is a schematic diagram showing the arrangement of color filters used in the color imaging device of the present invention. FIG. 1 is a schematic diagram showing an embodiment of the invention. In the figure ζ, 11 is a transparent Gη filter, 12
is a green (G) filter, 13 is a cyan (Cy) filter, 14 is a yellow (Ye) filter, 15 is a solid-state image sensor,
16 and 17 are IH delay lines, 18 is an adder circuit, 19 and 20
21 to 24 are switches, 21 to 24 are gate circuits, 5 and 26 are gate signals, 27 to 30 are limiters, 31 and 32 are two-way circuits, and 33 to 37 are low-pass fluorescent circuits 738 are process encoder circuits. The agent's 1st run upstream, Figure 1, Figure 2

Claims (1)

[Claims] Video signals corresponding to all color light and green light components are obtained alternately in the scanning line direction, video signals corresponding to cyan light and yellow light components are obtained alternately in the scanning line direction, and all color light and green light components are obtained alternately in the scanning line direction. A solid-state image sensor configured to obtain a video signal corresponding to a light component and a video signal corresponding to cyan light and yellow light components line-sequentially for each scanning line, and an output signal of the solid-state image sensor are integrated. a first delay line with a time delay corresponding to a horizontal scanning period and a second delay line with a time delay corresponding to a three-half scanning period, the first output signal not being delayed and the second delay line; The signal obtained by adding the third output signal delayed by the first delay line and the second output signal delayed by the first delay line are switched for each scanning line to correspond to continuous all-color light and green light components. A video signal corresponding to continuous cyan light and yellow light components is generated, and from these two continuous video signals, four video signals corresponding to all color light, green light, cyan light, and yellow light components are generated. a separation circuit that separates the four video signals, a matrix circuit that forms video signals corresponding to red light and blue light components from the four video signals separated, and a matrix circuit that separates the four video signals into video signals corresponding to the red light and blue light components. The amplitudes of the video signals corresponding to the separated all-color light, green light, cyan light, and yellow light components are adjusted so that video signals corresponding to the red light and blue light components can be obtained even if and a limiter circuit for adding the first output signal, the second output signal, and the third output signal to form a wideband luminance signal, and forming a color difference signal from the broadband luminance signal. a video signal circuit that generates a low-frequency component of a luminance signal; a horizontal contour forming circuit that generates a horizontal contour signal from the broadband luminance signal;
1. A color imaging device comprising at least a vertical contour forming circuit that senses a second-order differential vertical contour signal from the output signal and the third output signal.