JP3017312B2 - Color imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image pickup apparatus provided with an image pickup element in which a plurality of light receiving elements (pixels) are arranged two-dimensionally, and particularly to a color image pickup apparatus having a high resolution, a small amount of moiré and a low S / O ratio.
The present invention relates to a color imaging device capable of outputting an image having a good N ratio.

[0002]

2. Description of the Related Art FIGS. 6, 7 and 8 show examples of arrangements of color filters of a conventionally known color solid-state imaging device. FIG. 6 shows a so-called stripe filter in which a red light transmitting filter R, a green light transmitting filter G, and a blue light transmitting filter B are vertically arranged in stripes. 7 and 8 show a so-called mosaic filter. In FIG. 7, the green light transmitting filter G is vertically striped, and the red light transmitting filter R and the blue light transmitting filter B are each 2 pixels. In FIG. 8, a magenta light transmission filter Mg, a green light transmission filter Gr, a cyan light transmission filter Cy, and a yellow light transmission filter Ye are arranged in two pixels in the horizontal direction in every other row and two columns. , Eight color filters of four pixels in the vertical direction are defined as one unit, and are arranged in the order shown in FIG.

However, the image pickup device having such a color filter array has the following problems. That is, in the image pickup device provided with the color filter having the configuration shown in FIG. 6, since a color signal carrier is generated at a frequency of 1/3 of the sampling frequency, resolution up to a frequency of 1/2 of the sampling frequency which is the Nyquist frequency is performed. The resolution is inferior.

In an image sensor provided with a color filter having the structure shown in FIG. 7, R and B filters having different bands in a vertical direction are arranged side by side, so that color moire is likely to occur in the vertical direction. An unsightly scene comes out.

Since the image pickup device having the color filter shown in FIG. 8 is constituted by a complementary color filter having a wide band, color moire is less likely to occur than the image pickup device provided with the color filter shown in FIG. Since the color signal is formed by the difference signal between the output signals of the pixels, the S / N ratio of the color signal is poor, and the quantization error of the color signal increases when the output signal is quantized and digitally processed. Not preferred.

Further, in both the image pickup devices provided with the color filters having the structures shown in FIGS. 7 and 8, a color signal carrier is generated at a half frequency of the sampling frequency, so that the frequency is a half of the Nyquist frequency. Can not be resolved.

On the other hand, US Pat.
There is an image sensor having a color filter array called a Bayer array disclosed in Japanese Patent No. 65-65. As shown in FIG. 9, when the horizontal pitch of the pixels of the image sensor is P _H and the vertical pitch is P _V , the green light transmitting filter G has a horizontal pitch of 2P _H and a vertical pitch of A red light transmitting filter R arranged in an offset sampling structure offset horizontally by P _{H by} P _V
And the blue light transmitting filter B has a horizontal pitch 2P.
_H, in which are arranged in a rectangular grid-like sampling structure of vertical pitch 2P _V. It is known that when an image pickup device having such a Bayer array is used, a good image with less moire and a good S / N ratio can be obtained.

[0008]

However, the following problems occur even when the image pickup device having the Bayer array is used. That is, FIGS. 10A and 10B respectively show the first quadrant when the position of the signal carrier generated by the image sensor of the color filter shown in FIG. 9 is represented on a two-dimensional frequency plane (f _H , f _V ). FIG. Here, FIG.
In the characteristic diagram on the frequency plane shown in FIG. 9, a luminance signal is formed by directly switching and switching the output signal from each pixel of the image sensor of FIG. In the characteristic diagram, a luminance signal is formed using only a signal from a pixel of the image sensor of FIG. 9 where the G filter is arranged.

In any case, (1 / 2P
_It can be seen that color signal carriers are generated at ( _H , 0) and (0, 1 / 2P _V ). That is, in the case of an image pickup device having a Bayer arrangement, half of the sampling frequency is also used.
Since a chrominance signal carrier is generated at the frequency of, it is not possible to resolve up to half the sampling frequency which is the Nyquist frequency.

Furthermore, a luminance signal having a correct spectral characteristic cannot be obtained with a simple synthesized luminance signal using only a signal from a pixel in which a G filter is arranged, by switching and switching an output signal from each pixel. It adversely affects the color reproducibility of the output image. For this reason, processing for replacing only the low-frequency component of the luminance signal with a luminance signal having correct spectral characteristics has been conventionally performed, but a circuit scale for forming a luminance signal having this correct spectral characteristic is greatly increased. .

The present invention has been made in view of such a problem, and it is possible to obtain a luminance signal whose spectral characteristics have been corrected by a simple method, has a good resolution, has little moire, and has a high S / S ratio.
It is an object of the present invention to provide a color imaging device capable of obtaining an image having a good N ratio.

[0012]

According to the present invention, in order to achieve the above object, a color image pickup apparatus is constituted as in the following (1).

(1) A color image pickup apparatus for converting a subject image into an electric signal having luminance information and color information, the apparatus including the following components a, b, c, and d. a. Pixel pitch P _{H in the} horizontal direction, pitch P in the vertical direction
Image sensors arranged in a _V rectangular grid. b. A first color filter provided corresponding to the pixel and having an offset sampling structure offset horizontally by P _H at a horizontal pitch of 2P _H and a vertical pitch of P _{V; H,} a color filter array and a second color filter and the third color filter having a rectangular grid-like sampling structure of vertical pitch 2P _V. c. The first color signal, the second color signal, and the third color signal output from the pixels corresponding to the first color filter, the second color filter, and the third color filter are used to generate a first color signal. Only the signals of the pixels in the same column as the pixels of the second color signal among the color signals are synchronized, and the first signal obtained by taking a difference from the second color signal is obtained.
From the difference signal of the first color signal and the second difference signal obtained by taking the difference from the third color signal by synchronizing only the signals of the pixels in the same column as the pixel of the third color signal. First color signal forming means for forming color information, and only signals of pixels of the same row as pixels of the second color signal among the first color signals are synchronized to obtain a difference from the second color signal. A fourth difference signal obtained by synchronizing only the third difference signal and a signal of a pixel in the same row as the pixel of the third color signal among the first color signals to obtain a difference from the third color signal And second color information forming means for forming the color information from the first color information forming means and the second color in accordance with a frequency component in a scanning direction or a direction orthogonal to the scanning direction in the subject image. Color information forming means for switching between the information forming means.

D. The first difference signal or the third difference signal is multiplied by a constant with the second difference signal or the fourth difference signal, respectively, and these are multiplied by the first color signal, the second color signal, and the third color signal. Luminance information forming means for forming the luminance information by adding the signal to a signal obtained by combining at least one of the color signals.

[0015]

According to the structure of (1), the carrier of the color difference signal for the black-and-white subject in (1 / 2P _H , 0) and (0, ， P _V ) on the two-dimensional frequency space disappears,
Moire is suppressed.

Also, a signal obtained by multiplying the first and second or third and fourth difference signals by a constant multiple is added to the luminance information obtained by synthesis, and the spectral characteristic of the luminance information is corrected.

[0017]

The present invention will be described in more detail with reference to the following examples.
FIG. 1 is a block diagram of a "color image pickup apparatus" according to a first embodiment of the present invention. FIG. 9 shows an image sensor (sensor) 101.
An R, G, B filter (filter array) having a Bayer array shown in FIG. Image sensor 101 to 1
The image signal read for each pixel is separated into R, G, and B signals by a color separation unit 102, and gains of the R, G, and B signals are obtained from a white balance sensor (AWB) 120 by a white balance unit 111. The white balance is adjusted based on the obtained color temperature information, then the γ conversion is performed by the γ conversion unit 112, and then the A / D (analog-digital) converter 103 performs the A / D conversion.

The luminance signal is supplied to a switch circuit (SWY) 126
Arranged in read order by being switched by, it is taken as the luminance signal Y _S including the high-frequency component. This luminance signal Y _S is a first difference signal or a third difference signal R (γ power) −G ₁ (γ power), a second difference signal or a fourth difference signal B (γ power) − A signal obtained by adding a constant multiple of G ₂ (γ power) and an adder 117 are added, D / A converted by a D / A (digital-analog) converter 118, and output.

On the other hand, among the outputs of the A / D converter 103, G
The (γ-th power) signal is generated by a switch (SW) 128 in FIG.
At two timings, timing 1 shown in (a) or timing 2 shown in (b), the signal is separated into a G ₁ (γ power) signal and a G ₂ (γ power) signal at the positions shown in the figure. This can be achieved by switching the switch 128 every one horizontal scanning period, for example. These two timings 1, 2
Is switched in accordance with a luminance signal of a subject by a determination circuit 131 described later. G ₁ thus separated
(Γ power) signal, G ₂ (γ power) signal is R (γ power) signal, B
(Γ power) signal and interpolation filters 106, 107, 1
08, 109 and the signals R (γ
Power), G ₁ (γ power), G ₂ (γ power), and B (γ power). The interpolation filters 106 to 109 perform not only synchronization by interpolation but also linear processing such as two-dimensional low-pass filtering and edge enhancement. Since these processes are linear processes, the order may be interchanged with processes such as addition processing and matrix processing described later.

The synchronized R (γ power) signal, G ₁ (γ
The (power) signal becomes a first difference signal and a third difference signal R (γ power) −G ₁ (γ power) in an adder 129, and a B (γ power) signal and G
_{The 2} (γ power) signal is converted into a second difference signal and a fourth difference signal B (γ power) −G ₂ (γ power) by the adder 130, and these are input to the color difference signal matrix processing unit 113.

[0021]

(Equation 1)

Is performed, and the color difference signals RY, B
-Y is generated.

Here, it is assumed that the switching of the G ₁ (γ power) and G ₂ (γ power) signals is performed at the timing 1 shown in FIG. 2 (a), and in the frequency space (1 / 2P _H , 0) It is assumed that a black-and-white subject in ()) is collected by the image sensor 101. This subject is a vertical stripe with a period of 2P _H , and for such a subject, R (γ power) = G ₁ (γ power), B (γ power)
Power) = G ₂ (γ power), so that the adders 129 and 130
R (γ power) -G ₁ (γ power) signal, B (γ
Each of the (power) -G ₂ (γ power) signals becomes zero. therefore,
The color difference signal R output from the color difference matrix processing unit 113
-Y and BY also become zero and are not output. This means that the carrier of the color difference signal at the frequency (1 / 2P _H , 0) disappears. In other words, the carrier of the R (γ-th power) signal and the carrier of the G ₁ (γ-th power) signal on the frequency (1 / 2P _H , 0) are in phase, and B (γ
The signal carrier and the G ₂ (γ power) signal carrier have the same phase, and therefore, these first and second difference signals R (γ power) −G ₁ (γ power) and B (γ power) ) -G ₂ (γ power)
Since the carrier at this frequency can be eliminated, no carrier of the color difference signal is generated.

Next, assuming that the switching of the G ₁ (γ power) and G ₂ (γ power) signals is performed at the timing 2 shown in FIG. 2B, on the frequency space (0, 1 / 2P _V ) Is taken by the image sensor 101. This object is horizontal stripe period 2P _V, for such a subject is output from the adder 129, 130 R
(Γ power) -G ₁ (γ power) signal, B (γ power) −G ₂ (γ
All of the signals are zero. Therefore, the color difference signals RY and BY output from the color difference matrix processing unit 113 are also zero and are not output. This means that the frequency (0,1 / 2)
P _V ) means that the carrier of the color difference signal disappears. In other words, the frequency (0, 1 / 2P _V )
The carrier of the R (γ power) signal and the carrier of the G ₁ (γ power) signal are in phase, and the carrier of the B (γ power) signal and the carrier of the G ₂ (γ power) signal are in phase. Therefore, these third and fourth difference signals R (γ power) −G ₁ (γ
The carrier can be eliminated at this frequency of (power), B (γ power) −G ₂ (γ power), so that no carrier of the color difference signal is generated.

These color difference signals are D / A converted by the following D / A converters 114 and 115 and output.

Further, a third difference signal R (γ power) -G ₁ (γ
) And the fourth difference signal B (γ power) −G ₂ (γ power) are multiplied by constants by constant coefficient multipliers 132 and 133,
Is added to the luminance signal Y _S by an adder 117,
A luminance signal Y having a corrected spectral characteristic can be obtained.

The principle will be described below. Image sensor 10
The output signals from each pixel are simply synthesized, and the obtained luminance signal is set to Y _S. In this embodiment, the luminance signal Y _S is obtained by switching the output signal from each pixel by the switch circuit 126, but one of the color-separated color signals, for example, the G signal is used as it is. It may be what was. In contrast, the corrected luminance signal to spectral characteristics equal to the luminosity and Y _L. The luminance signal Y _L can be formed by a linear combination of the synchronized color signals.

[0028]

(Equation 2)

Can be expressed as In the case of the NTSC system, δ = 0.30, α + β = 0.59, ε = 0.11 (2). The luminance signal Y _L has a lower band than the luminance signal Y _S. Of the luminance signal Y _S, the luminance signal having the same bandwidth as the Y _L and Y _SL.

[0030] At this time, the luminance signal Y low-frequency portion of the Y _S Y
By replacing the luminance signal Y _L having a correct spectral characteristics _SL, it is corrected. That is, Y = (Y _S −Y _SL ) + Y _L = Y _L + (Y _L −Y _SL ) (3) Here, the luminance signal Y _SL can be represented by a linear combination of each color signal. this

[0031]

(Equation 3)

It is assumed that At this time, the parentheses on the right side of the equation (3) are as follows. That is,

[0033]

(Equation 4)

Here, if δ−s = t−α, then s + t = α + δ δ + α + β + ε = s + t + u + w (= 1), so β + ε = u + w, and thus ε−w = u−β, where C ₁ = δ−s = t−α... (5) C ₂ = ε−w = u−β (6)

[0035]

(Equation 5)

Substituting this into equation (3)

[0037]

(Equation 6)

## EQU4 ## Therefore, the spectral characteristics of the luminance signal Y are corrected by adding the first and the second luminance signals to the luminance signal Y _S obtained by the simple synthesis.
The second difference signal or the third and fourth difference signals R (γ power) -G
It can be performed by adding a constant multiple of ₁ (γ power) and R (γ power) −G ₂ (γ power).

When the luminance signal Y _S is obtained by being switched by the switch circuit 126, s, t, u and w in the equation (4) are as follows: s = t = u = w = 0.25 .. (8), α = 0.20, β = 0.39, C ₁ = 0.05, C ₂ = −0.14 from the equations (2), (5) and (6). 9) is obtained.

When the luminance signal Y _S is a signal using the G signal as it is, s, t, u and w in the equation (4) are represented by s = w = 0, t = u = 0.5 (...) 10), α = 0.20, β = 0.39 C ₁ = 0.30, C ₂ = 0.11 (11) are obtained from (2), (5) and (6). .

The luminance signal Y whose spectral characteristics have been corrected in this manner is D / A converted by the D / A converter 118 and output. In general the color difference signal R-Y, B-Y, because sufficient bandwidth is narrower than in the low-frequency component Y _L is the luminance signal Y of the luminance, interpolated synchronized been R (gamma-th power), G ₁ (gamma-th power) , G ₂ (γ
The processing in the adders 129, 130, the color difference matrix processing unit 113, the luminance signal generation circuit 127, and the like of the (power) and B (γ) signals may be performed with a clock that is slower than the processing of the luminance signal Y by performing thinning or the like. .

When the output signal obtained from the processing block diagram shown in FIG. 1 is recorded in an analog form, the D / A converter 1
18,114,115 is required, some magnetic media, magneto-optical media, E ₂ PROM (electricallyerasabl P
It does not need to be inserted when digital recording is performed in ROM).

Next, the judgment circuit 131 will be described. FIG. 3A shows one configuration of the determination circuit. Here, a horizontal band-pass filter 31 is applied to the luminance signal Y output from the switch circuit 126 to extract a high-frequency component in the horizontal direction. This is input to the comparison circuit 32 and compared with a certain threshold level. Then, when it is determined that the level is higher than the threshold level and the high frequency component in the horizontal direction is large, the timing 1 for extinguishing the carrier of the color difference signal in the horizontal direction is selected,
Otherwise, the timing 2 for eliminating the carrier of the color difference signal in the vertical direction is selected (see FIG. 2).

The determination circuit 131 may have the configuration shown in FIG. That is, a vertical band-pass filter 61 is applied to the luminance signal Y output from the switch circuit 126 to extract a vertical high-frequency component. This is input to the comparison circuit 62 and is compared with a certain threshold level. Then, when it is determined that the high-frequency component in the vertical direction is larger than the threshold level, the timing 2 for extinguishing the carrier of the color difference signal in the vertical direction is selected, otherwise, the carrier of the color difference signal in the horizontal direction is selected. Timing 1 for extinguishing is selected.

As described above, in the present embodiment, since the color filters of the Bayer array are used, the moiré is small, the S / N ratio is good, and the signal processing means suitable for the Bayer array is used. The resolution is good.

Further, luminance information with corrected spectral characteristics can be obtained by a simple method.

Next, a second embodiment of the present invention will be described. FIG.
Shows a signal processing block diagram of the “color imaging device” of the present embodiment. The image sensor (sensor) 401 is provided with R, G, and B filters in a Bayer arrangement shown in FIG. An image signal read for each pixel from the image sensor 401 is separated into R, G, and B signals by a color separation unit 402, and the gains of the R, G, and B signals are adjusted by a white balance unit 411 by a white balance sensor 420. The white balance is adjusted based on the color temperature information obtained from the
, And then A / D converted by the A / D converter 403.

The luminance signal is obtained by two-dimensionally interpolating the offset sampling structure of the G (γ-th power) signal by the interpolation filter 425 and then D / A-converted by the D / A converter 418 and output. The interpolation filter performs not only synchronization by interpolation but also processing such as two-dimensional low-pass filtering and edge enhancement.

On the other hand, of the output of the A / D converter 403, G
The (γ-th power) signal is generated by the switch 428 at two positions G _{1 and} T 1 shown in FIG. 2A or at timing 2 shown in FIG.
(Γ power) signal and G ₂ (γ power) signal. This allows the switch 428 to be switched, for example, every horizontal scanning period. Switching between the two timings 1 and 2 is performed by a determination circuit 431 described later in accordance with the luminance signal of the subject.

The G ₁ (γ power) signal thus separated,
The G ₂ (γ power) signal is an interpolation filter 406, 407, 408, 409 together with the R (γ power) signal and B (γ power) signal.
, And the synchronized signals R (γ power) and G ₁
(Γ power), G ₂ (γ power), and B (γ power). The interpolation filter performs not only synchronization by interpolation but also linear processing such as two-dimensional low-pass filtering and edge enhancement. Since these processes are linear processes, the order of processes such as an addition process described later may be changed. The synchronized R (γ power) signal and G ₁ (γ power) signal become a difference signal R (γ power) −G ₁ (γ power) in an adder 429, and the B (γ power) signal and G ₂ (γ power) The adder 430 outputs the difference signal B (γ)
Power) −G ₂ (γ power), as in the first embodiment, and the color difference signals R−Y, B by the color difference signal matrix risk processing unit 413.
-Y is generated.

[0051] _{Here, G 1 (γ 1),} G 2 (γ -th power) switching signal is supposed to be performed at the timing 1 shown in FIG. 2 (a), a frequency space (1 / 2P _H, 0 It is assumed that the black-and-white subject in () is sampled by the image sensor 401. This subject is a vertical stripe with a period of 2P _H , and for such a subject, the R (γ power) -G ₁ (γ power) signal and B (γ power) -G output from the adders 429 and 430. _Two
(Γ power) signals are all zero. Therefore, the color difference signal R-
Y and BY become zero and are not output. This means that the carrier of the color difference signal at the frequency (1 / 2P _H , 0) disappears. In other words, the frequency (1 /
2P _H , 0) and the carrier of the R (γ power) signal and G ₁
The carrier of the (γ power) signal is in phase, and the carrier of the B (γ power) signal and the carrier of the G ₂ (γ power) signal are in phase, and therefore, the first and second difference signals R (Γ power)
Since the carrier at this frequency of −G ₁ (γ power), B (γ power) −G ₂ (γ power) can be eliminated, no carrier of the color difference signal is generated.

Next, assuming that the switching of the G ₁ (γ power) and G ₂ (γ power) signals is performed at the timing shown in FIG. 2B, (0, Ｐ P _V ) Is taken by the image sensor 401. This object is horizontal stripe period 2P _V, for such a subject is output from the adder 429 and 430 R
The (γ power) -G ₁ (γ power) and B (γ power) -G ₂ (γ power) signals are all zero. Therefore, the color difference signals RY, BY
Becomes zero and is not output. This means that the frequency (0,1 /
2P _V ) means that the carrier of the color difference signal disappears. In other words, the frequency (0, 1 / 2P
_V ), the carrier of the R (γ power) signal and the carrier of the G ₁ (γ power) signal have the same phase, and the carrier of the B (γ power) signal and the carrier of the G ₂ (γ power) signal have the same phase. Therefore, these third and fourth difference signals R (γ power) −G ₁ (γ
Since the carrier at this frequency of (power), B (γ power) −G ₂ (γ power) can be eliminated, no carrier of the color difference signal is generated. These color difference signals are D / A converted by successive D / A converters 414 and 415 and output. In general, the color difference signals RY and BY are equivalent to the luminance signal Y.
Since the bandwidth is sufficiently narrower than that of
The processing of the (γ-th power), Y ₁ (γ-th power), Y ₂ (γ-th power), and B (γ-th power) signals in the adders 429, 430, and the like is performed using a clock that is slower than the luminance signal processing by performing thinning and the like. May go.

When an output signal obtained from the processing block diagram shown in FIG. 4 is recorded in an analog form, the D / A converter 4
18, 414, and 415 are necessary, but need not be included when digital recording is performed on any magnetic medium, magneto-optical medium, E ² PROM, or the like.

Next, the judgment circuit 431 will be described. This embodiment also uses the determination circuit having the configuration shown in FIG.
In the configuration of FIG. 3A, the luminance signal Y output from the interpolation filter 425 is subjected to the horizontal band-pass filter 31 to extract a horizontal high-frequency component. This is input to the comparison circuit 32 and is compared with a certain threshold level. Then, when it is determined that the level is larger than the threshold level and the horizontal high-frequency component is large, the timing 1 for extinguishing the carrier of the color difference signal in the horizontal direction is selected. Otherwise, the carrier of the color difference signal in the vertical direction is selected. Timing 2 to be extinguished is selected (see FIG. 2).

In the configuration of FIG. 3B, the interpolation filter 42
A vertical band-pass filter 61 is applied to the luminance signal Y output from 5 to extract high-frequency components in the vertical direction.
This is input to the comparison circuit 62 and is compared with a certain threshold level. Then, when it is determined that the high-frequency component in the vertical direction is larger than the threshold level, the timing 2 for extinguishing the carrier of the color difference signal in the vertical direction is selected, otherwise, the carrier of the color difference signal in the horizontal direction is selected. Timing 1 to be extinguished is selected (see FIG. 2).

It should be noted that the color filters of the image sensor need not necessarily be R, G, and B filters, and the first, second, and third color filters are Y (spectral characteristics of the luminance signal) as shown in FIG. , Or a Bayer array in which the first, second, and third color filters are W (white), R, and B, as shown in FIG. 5B.
When the first color signal is separated as shown in FIGS. 2A and 2B and the first to fourth difference signals are formed, the color difference signal R−
As shown in the above “Equation 1”, Y, BY are the first to fourth.
Any signal can be used as long as it can be obtained by a linear operation using a matrix from the difference signal of. (The coefficient of the matrix does not need to be the same as “Equation 1”.)

[0057]

As described above, according to the present invention,
By providing a Bayer-array filter array in the image sensor and appropriately performing signal processing, it is possible to obtain luminance information in which spectral characteristics can be corrected by a simple method, and to obtain good resolution, low moire, and S / N. A color imaging device capable of obtaining an image having a good ratio can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is an explanatory view of a first embodiment.

FIG. 3 is a configuration diagram of a determination circuit;

FIG. 4 is a block diagram of a second embodiment.

FIG. 5 shows an example of a Bayer arrangement.

FIG. 6 is a diagram showing an example of an arrangement of color filters.

FIG. 7 is a diagram showing an example of an arrangement of color filters.

FIG. 8 is a diagram showing an example of an arrangement of color filters.

FIG. 9 shows an example of a Bayer arrangement.

FIG. 10 is a diagram showing positions of signal carriers by the color filters of FIG. 9;

[Explanation of symbols]

 Reference Signs List 101 Image sensor 106 to 109 Interpolation filter 128 Switch 129, 130 Adder 131 Judgment circuit 132, 133 Constant coefficient multiplier 117, 134 Adder

Claims (1)

(57) [Claims] 1. A color imaging apparatus for converting a subject image into an electric signal having luminance information and color information, comprising:
A color imaging apparatus comprising the components (b), (c) and (d). a. Pixel pitch P _{H in the} horizontal direction, pitch P in the vertical direction
Image sensors arranged in a _V rectangular grid. b. A first color filter provided corresponding to the pixel and having an offset sampling structure offset horizontally by P _H at a horizontal pitch of 2P _H and a vertical pitch of P _{V; H,} a color filter array and a second color filter and the third color filter having a rectangular grid-like sampling structure of vertical pitch 2P _V. c. The first color signal, the second color signal, and the third color signal output from the pixels corresponding to the first color filter, the second color filter, and the third color filter are used to generate a first color signal. Only the signals of the pixels in the same column as the pixels of the second color signal among the color signals are synchronized, and the first signal obtained by taking a difference from the second color signal is obtained.
From the difference signal of the first color signal and the second difference signal obtained by taking the difference from the third color signal by synchronizing only the signals of the pixels in the same column as the pixel of the third color signal. First color signal forming means for forming color information, and only signals of pixels of the same row as pixels of the second color signal among the first color signals are synchronized to obtain a difference from the second color signal. A fourth difference signal obtained by synchronizing only the third difference signal and a signal of a pixel in the same row as the pixel of the third color signal among the first color signals to obtain a difference from the third color signal And second color information forming means for forming the color information from the first color information forming means and the second color in accordance with a frequency component in a scanning direction or a direction orthogonal to the scanning direction in the subject image. Color information forming means for switching between the information forming means. d. The first difference signal or the third difference signal is multiplied by a constant with the second difference signal or the fourth difference signal, respectively, and these are multiplied by the first color signal, the second color signal, and the third color signal. Luminance information forming means for forming the luminance information by adding the signal to a signal obtained by combining at least one of the color signals.