JP3112531B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to an imaging apparatus, in particular, using a single imaging element, an imaging device to obtain a color image signal provided color decomposition filters the image sensor
About the.

[0002]

2. Description of the Related Art As such conventional image pickup apparatuses, there are an image pickup apparatus using one image pickup element in an image pickup section and an image pickup apparatus using a plurality of image pickup elements.

In an image pickup apparatus using a plurality of image pickup elements, for example, a three-plate type color solid-state image pickup apparatus, a solid-state image pickup element is provided for each of red, green, and blue light. , Green and blue signals (primary color signals) are subjected to white balance processing and gamma processing, and a luminance signal is generated from the primary color signals subjected to such processing (3).
Channel process). According to this, there is no luminance reproduction error due to the gamma processing or the color temperature of the light source, and a luminance signal that is always faithful to the subject can be obtained.

On the other hand, a single-chip color solid-state imaging device in which a color image signal is obtained using one solid-state imaging device is smaller and less expensive than a three-chip color solid-state imaging device. Since the solid-state imaging device is provided with a plurality of color separation filters having different spectral sensitivities to generate a color signal, it is impossible to generate a luminance signal from the color signal subjected to white balance processing from the viewpoint of poor resolution. For this reason, as described in, for example, JP-A-60-62290, the output signal of the solid-state imaging device is gamma-processed,
The signal subjected to the gamma processing was used as a luminance signal.

[0005]

In the conventional single-panel color solid-state imaging device, since the luminance signal is not subjected to white balance processing, when a chromatic object is imaged under a light source having a low color temperature and a high color temperature. However, there is a problem that a luminance signal different from the actual one is generated.

Further, as described above, the output signal of the solid-state imaging device in which the red, green, and blue signals are mixed is subjected to gamma processing to generate a luminance signal, as in a three-plate type color solid-state imaging device. , And a gamma process is performed on each of the blue signals to generate a luminance signal. Therefore, even if a gamma process is performed on the output signal of the solid-state imaging device as a luminance signal as described above, Is not faithful to the subject.

[0007] In order to solve such a problem, a first object of the present invention is to suppress a luminance reproduction error and obtain a luminance signal faithful to an object even when imaging under a light source having a low color temperature and a high color temperature. Taking by a single imaging device to be able
An imaging device is provided.

[0008] A second object of the present invention, shooting with a single imaging device to be able to obtain a faithful luminance signal to the subject by suppressing the luminance reproduction error based on gamma processing
An imaging device is provided.

[0009]

In order to achieve the first object, according to the present invention, a primary color signal is generated from an output signal of an image pickup section having a plurality of color separation filters having different spectral sensitivities, and white balance is obtained. Means for correcting the output signal of the image pickup unit to generate a first luminance signal; and processing the primary color signal having been subjected to white balance correction to generate the first luminance signal.
Of the frequency band substantially equal to the low frequency component of the luminance signal of
Means for generating a luminance signal, a subtraction circuit for detecting a difference signal between the second luminance signal and the low-frequency component of the first luminance signal, and a signal having a level equal to or lower than a predetermined level based on the difference signal. A core circuit for removing the component, and an addition circuit for adding the output signal of the core circuit to the first luminance signal so that the output signal has a predetermined ratio with the low frequency component of the first luminance signal. A configuration is provided. It is assumed that the predetermined ratio is in accordance with the color temperature of the light source that irradiates the photographing subject or the aperture value of the lens.

In order to achieve the second object, the present invention further provides a gamma processing of the primary color signal white balance corrected by the white balance processing circuit.
And a second gamma circuit for performing gamma processing on the first luminance signal, generating the second luminance signal from the primary color signals gamma-processed by the first gamma circuit, The subtraction circuit includes a second luminance signal generated from the primary color signal that has been gamma-processed by the first gamma circuit and the first luminance signal that has been gamma-processed by the second gamma circuit.
And a difference signal between the luminance signal and the low-frequency component.

[0011]

Since the low frequency component of the luminance signal is generated from the color signal subjected to the white balance correction, even if a chromatic subject is imaged under a light source having a low color temperature and a high color temperature,
No luminance reproduction error occurs. In addition, since the high-frequency component of the luminance signal is not replaced at all, there is no deterioration in resolution.

Further, by generating a signal to be replaced from a gamma-processed color signal, it is possible to suppress a luminance reproduction error based on non-linear processing (gamma processing). A luminance signal can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing one embodiment of an imaging apparatus according to the present invention, wherein 1 is an imaging device, 2 is a signal processing circuit,
3 is a luminance signal generation circuit, 4 is a subtraction circuit, 5 is a core circuit,
6 is a multiplication circuit, 7 and 8 are addition circuits, 9 is a color signal generation circuit, 10 is a white balance processing circuit, 11 is an addition circuit, 12 is a color difference matrix circuit, and 13 is an encoding circuit.

In FIG. 1, an output signal of an image sensor 1 obtained by photoelectric conversion is processed by a signal
Signals S1 and S2 are generated, and the respective color signal generation circuits 9
Is supplied to the luminance signal generation circuit 3. Here, a specific example of the signal processing circuit 2 will be described with reference to FIG.
However, 14 is an amplifier, 15 is an A / D converter, 16,
17 is a coefficient circuit, 18 and 19 are 1H delay circuits, and 20 is an addition circuit.

In FIG. 1, the output signal of the image sensor 1 is
After being amplified by the amplifier 14, it is converted into a digital signal by the A / D converter 15. This digital signal (hereinafter referred to as the current signal) is supplied to 1H delay circuits 18 and 19 for 1H.
(However, 1H is one horizontal scanning period). The current signal is also multiplied by a factor of 1/2 in a coefficient circuit 16,
The output signal of the 1H delay circuit 19 is also multiplied by the coefficient circuit 17 by a factor of 1/2. The output signals of the coefficient circuits 16 and 17 are added by an adder circuit 20, and the output signal of the adder circuit 20 is the signal S1. Also, the 1H delay circuit 18
Is the signal S2 described above. That is, the signal S1 is an average signal of the current signal and a signal delayed by 2H from the current signal,
The signal S2 is a signal delayed by 1H from the current signal.

Returning to FIG. 1, in the color signal generation circuit 9, the output signals S1 and S2 of the signal processing circuit 2 are separated for each color component of a color separation filter provided in the image sensor 1, and the color components are calculated. The red, green and blue primary color signals (r, g,
b) is generated. These three primary color signals are subjected to white balance correction processing by a white balance processing circuit 10,
Red and blue signals (white balance corrected)
The R signal and the B signal are supplied to the addition circuit 11 and the color difference matrix circuit 12, and the green signal (hereinafter, referred to as a G signal) whose white balance has been corrected is supplied to the addition circuit 11. The adding circuit 11 adds the R, G, and B signals to generate a white balance corrected luminance signal (Yrgb). The luminance signal (Yrgb) is supplied to the color difference matrix circuit 12 and the subtraction circuit 4. In the color difference matrix circuit 12, two color difference signals (R-Yrgb, B-Yrgb) are generated from the R and B signals and the luminance signal (Yrgb), and supplied to the encoder circuit 13, respectively.

On the other hand, in the luminance signal generating circuit 3, a composite signal (YH) of a high frequency component and a vertical edge component of the luminance signal from the output signals S1 and S2 of the signal processing circuit 2 and a low frequency component (YL) of the luminance signal Are generated. The low frequency component (YL) of the luminance signal is supplied to the subtraction circuit 4 and the addition circuit 7, and the composite signal (YH) is supplied to the addition circuit 8. Here, a specific example of the luminance signal generation circuit 3 will be described with reference to FIG. Here, 21 is an addition circuit, 22 is an LPF (low-pass filter), 23 is a horizontal aperture correction circuit, and 24 is a vertical aperture correction circuit.

In FIG. 1, an output signal S1 of the signal processing circuit 2 is supplied to an LPF 22 and band-limited. This L
The output signal of the PF 22 is a low frequency component (Y
L). Further, the output signal S1 of the signal processing circuit 2 is supplied to the horizontal aperture correction circuit 23, and the high frequency component of the luminance signal is extracted. Further, the output signals S1 and S2 of the signal processing circuit 2 are supplied to a vertical aperture correction circuit 24, and a vertical edge component in the luminance signal is extracted. The output signal of the horizontal aperture correction circuit 23 and the output signal of the vertical aperture correction circuit 24 are added by the addition circuit 21, and the output signal of the addition circuit 21 is the above-described composite signal (YH).

Returning to FIG. 1, in the subtraction circuit 4, the low frequency component (YL) of the luminance signal is subtracted from the luminance signal (Yrgb) output from the addition circuit 11, and the correction signal (Yrgb) is subtracted.
−YL) is generated, and a signal component below a level determined by a coefficient K1 set in advance is deleted (coring-processed) in the core circuit 5 and then multiplied by a coefficient K2 in a multiplication circuit 6 to generate a correction signal. Is added to the low frequency component (YL) of the luminance signal from the luminance signal generation circuit 3 by the addition circuit 7.

The low frequency component of the corrected luminance signal from the adding circuit 7 is added to the combined signal (YH) from the luminance signal generating circuit 3 by the adding circuit 8 and supplied to the encoder circuit 13 as the luminance signal Y. In the encoder circuit 13, a color video signal is generated from the luminance signal Y and the color difference signals (R-Yrgb, B-Yrgb) from the color difference matrix circuit 12.

As described above, in this embodiment, the luminance signal Yrgb generated from the color signal subjected to the white balance correction is used.
Replaces the low-frequency component YL of the luminance signal generated from the output of the image sensor that has not been subjected to white balance correction, so that the level of the luminance signal does not change due to the color temperature of the light source.

The coefficient K1 of the core circuit 5 is subtracted from the subtraction circuit 4
If the correction signal (Yrgb-YL) is set to a level at which no coring processing is performed, the output signal of the multiplication circuit 6 is (Yrgb-YL) × K2, and the luminance signal Y output from the addition circuit 8 is Y = Yrgb × K2 + YL × (1−K2) + YH. When K2 = 1, Y = Yrgb + YH, K2 = 0.
In this case, Y = YL + YH (the luminance signal Y when K2 = 1 has its low-frequency component replaced by the luminance signal Yrgb from the adder circuit 11). Therefore,
By changing K2, the luminance signal (YL + YH) generated from the output signal of the image sensor 1 and the luminance signal (Yrgb + YH) subjected to white balance correction can be smoothly switched. Yrg
By making the frequency band of b and the low frequency component YL substantially coincide with each other, the frequency band of the luminance signal does not change even if the coefficient K2 changes.

Further, by setting the coefficient K1 to an appropriate value, only when the difference between the level of the luminance signal generated from the output signal of the image pickup device 1 and the actual luminance level of the subject becomes a certain amount or more, It is also possible to smoothly switch the luminance signal to a luminance signal subjected to white balance correction. By doing so, when the luminance level of the color imaging device is close to the luminance level of the actual object, the luminance signal is not replaced as described above. Therefore, especially when an achromatic object or the like is imaged, S / N Deterioration can be suppressed.

FIG. 3 is a block diagram showing another embodiment of the image pickup apparatus according to the present invention, wherein 25 is an addition circuit, 26 is a white balance control circuit, 27 is a color temperature detection circuit, and 28 is
Is a coefficient circuit, and portions corresponding to those in FIG.

In FIG. 3, the color difference matrix circuit 12
The color difference signals (R-Yrgb, B-Yrgb) generated in step (1) are supplied to the encoder circuit 13 and also to the white balance control circuit 26. In the white balance control circuit 26, these color difference signals (R-Yrgb, BY)
rgb), the gain of the primary color signal (r, b) in the white balance processing circuit 10 is calculated, and the calculated gain values are supplied to the white balance processing circuit 10 and the color temperature detection circuit 27. In the color temperature detection circuit 27, the color temperature of the light source is detected from the gains of the r and b signals, and the coefficient circuit 28 calculates the coefficient K2 of the multiplication circuit 6 according to the detection result. Therefore, the coefficient K2 of the multiplying circuit 6 depends on the color temperature of the light source that irradiates the imaging subject with light.

The following is the same as the embodiment shown in FIG.
On the other hand, in the luminance signal generation circuit 3, a high frequency component YH and a low frequency component YL of the luminance signal are generated, and the low frequency component YL is supplied to the subtraction circuit 4 and the addition circuit 25, and the high frequency component Y
H is supplied to the adding circuit 25. The correction signal (Yrgb-YL) generated by the subtraction circuit 4 is subjected to coring processing at a level determined by the coefficient K1 by the core circuit 5, and is multiplied by the coefficient K2 from the coefficient circuit 28 by the multiplication circuit 6 to obtain an addition circuit 7
Thus, the high frequency component YH and the low frequency component YL are added.

This embodiment is different from the embodiment shown in FIG. 1 in that the coefficient K2 is generated in real time in accordance with the color temperature of the light source. YL + YH) and the luminance signal (Yrgb + YH) subjected to the white balance correction can be smoothly switched according to the color temperature of the light source. Therefore, an effect essentially equivalent to that of the embodiment shown in FIG. 1 can be obtained except that the composition of the low frequency component of the luminance signal automatically changes according to the color temperature of the light source. Note that the color temperature detection circuit 2
7 and the coefficient circuit 28 may be realized by a microcomputer.

FIG. 4 is a block diagram showing still another embodiment of the image pickup apparatus according to the present invention.
Is an aperture, 31 is an aperture control circuit, 32 is a coefficient circuit,
Parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 4, light from a subject (not shown) that has passed through the lens 29 and the aperture 30 is irradiated on the image pickup device 1, and a signal is generated by photoelectric conversion as in each of the above embodiments. It is supplied to the processing circuit 2. This aperture 30
Is controlled by the aperture control circuit 31. Coefficient circuit 32
Forms a coefficient K2 of the multiplication circuit 6 in accordance with a signal representing the aperture value of the aperture 31 from the aperture control circuit 31. Therefore, the coefficient K2 changes in real time according to the aperture value of the aperture 30.

As described above, in this embodiment, the luminance signal (YL + YH) generated by the luminance signal generating circuit 3 and the luminance signal (Low-frequency component subjected to the white balance correction processing) are processed in real time according to the aperture value. Yrgb + YH). Other than that,
It is essentially equivalent to the embodiment shown in FIG. The aperture control circuit 31 and the coefficient circuit 32 may be realized by a microcomputer.

FIG. 5 is a block diagram showing still another embodiment of the image pickup apparatus according to the present invention. Reference numerals 33 and 34 denote gamma circuits, and parts corresponding to those in FIG. Is omitted.

In FIG. 5, the high frequency component YH and the low frequency component YL of the luminance signal from the luminance signal generating circuit 3 are respectively gamma-processed by the gamma circuit 33, the high frequency component YH is added to the adding circuit 8, and the low frequency component YL is The signals are supplied to the subtraction circuit 4 and the addition circuit 7, respectively. Also, a white balance processing circuit 1
The R, G, and B signals output from 0 are respectively supplied to the gamma circuit 34.
These R 'and B' are gamma-processed and gamma-processed.
The signal is sent to a color difference matrix circuit 12 and an addition circuit 11,
The gamma-processed G ′ signals are supplied to the adders 11 respectively. Therefore, in the adder circuit 11, the gamma-processed R
A luminance signal Yrgb 'is generated from the', G ', and B' signals.

The subtraction circuit 4 generates a difference component between the luminance signal Yrgb 'and the gamma-processed low frequency component YL', and a correction signal (Yrgb'-YL ').
Is subjected to a coring process by a coefficient K1, multiplied by a coefficient K2 by a multiplication circuit 6, and added to a low frequency component YL 'by an addition circuit 7.

As described above, in this embodiment, since the low-frequency component of the luminance signal is replaced after the gamma processing, the luminance reproduction error based on the gamma processing can be suppressed. When the coefficient K1 of the core circuit 5 is set to a level at which the coring process is not performed on the correction signal and the coefficient K2 = 1, the input luminance signal Y ′ of the encoding circuit 13 is expressed as follows: Y ′ = α · R ′ + β · G ′ + γ · B ′ + YH ′ (however,
α, β, and γ are constants), and although some errors occur in the high-frequency component YH ′, since these errors are at a level that can be neglected sufficiently, luminance reproduction faithful to the subject can be obtained.

Also, by changing the coefficient K2,
It is also possible to smoothly switch between a luminance signal that has been gamma-processed in a state where the R, G, and B signals are mixed and a luminance signal that has been generated by gamma-processing each of the R, G, and B signals.
Since the gamma-processed R, G, and B signals have been subjected to white balance correction, the same effects as those of the embodiment shown in FIG. 1 can be obtained.

The embodiment shown in FIG. 6 is obtained by adding gamma circuits 33 and 34 shown in FIG. 5 to the embodiment shown in FIG. Therefore, the difference between the luminance signal Yrgb 'generated by the adding circuit 11 from the gamma-processed R', G ', and B' signals and the low-frequency component YL 'of the gamma-processed luminance signal is used as a correction signal. After the signal is subjected to coring processing by the core circuit 5, the multiplication circuit 6 multiplies the coefficient by a coefficient K2 corresponding to the color temperature of the light source, and the addition circuit 25 gamma-processes the high-frequency component YH 'and low-frequency component YL of the luminance signal ´.

As described above, in this embodiment, since the luminance signal subjected to the gamma processing is replaced, the luminance reproduction error based on the gamma processing can be suppressed as in the embodiment shown in FIG. The coefficient K2 depends on the color temperature of the light source, and the gamma-processed R ', G', and B 'signals have been subjected to white balance correction, so that the same effect as in the embodiment shown in FIG. 3 can be obtained.

The embodiment shown in FIG. 7 is obtained by adding gamma circuits 33 and 34 shown in FIG. 5 to the embodiment shown in FIG. Therefore, the difference between the luminance signal Yrgb 'generated by the adding circuit 11 from the gamma-processed R', G ', and B' signals and the low-frequency component YL 'of the gamma-processed luminance signal is used as a correction signal. After the signal is subjected to coring processing by the core circuit 5, the coefficient K corresponding to the aperture value of the aperture 30 is calculated by the multiplication circuit 6.
The sum is multiplied by 2 and added to the high frequency component YH ′ and the low frequency component YL ′ of the luminance signal that has been gamma-processed by the addition circuit 25.

As described above, in this embodiment, since the luminance signal subjected to the gamma processing is replaced, the luminance reproduction error based on the gamma processing can be suppressed as in the embodiment shown in FIG. The coefficient K2 depends on the aperture value of the aperture, and the gamma-processed R ', G', and B 'signals have been subjected to white balance correction, so that the same effect as in the embodiment shown in FIG. 4 can be obtained.

FIG. 8 is a block diagram showing still another embodiment of the image pickup apparatus according to the present invention, wherein 35 and 36 are adder circuits, and 37 is an LPF (low-pass filter) circuit. Are denoted by the same reference numerals, and redundant description is omitted.

In FIG. 8, the high frequency component YH and the low frequency component YL of the luminance signal output from the luminance signal generating circuit 3 are added by an adding circuit 35. The luminance signal output from the addition circuit 35 is supplied to the subtraction circuit 4 and the addition circuit 36. In the subtraction circuit 4, R, G,
A difference between the luminance signal Yrgb formed from the B signal and the luminance signal from the adding circuit 35 is formed, and this difference is supplied to the LPF circuit 37 to remove the high frequency component. This LP
The output signal of the F circuit 37 is subjected to coring processing in the core circuit 5 as a correction signal, similarly to the embodiment shown in FIG.
The coefficient K2 is multiplied by the multiplication circuit 6 and added to the luminance signal from the addition circuit 35 by the addition circuit 36.

According to this embodiment, by making the pass band of the LPF circuit 37 substantially equal to the frequency band of the luminance signal Yrgb, the correction signal output from the LPF circuit 37 can generate the luminance signal Yrgb and the luminance signal of the same frequency band. This is formed from the low-frequency component of the luminance signal output from the circuit 3, and the replacement with the luminance signal Y obtained by the adding circuit 36 is more accurate than in the embodiment shown in FIG. Become.

It is needless to say that, as in the embodiment shown in FIG. 1, the adding circuit 36 adds the correction signal from the multiplying circuit 6 to the low frequency component YL, and then adds the high frequency component YH to the added signal. You may make it add.

The embodiment shown in FIG. 9 is obtained by adding gamma circuits 33 and 34 to the embodiment shown in FIG. 8 as shown in FIG. 5, and has the effect of the embodiment shown in FIG. In addition to
The same effect as the embodiment shown in FIG. 5 can be obtained.

In the embodiment shown in FIGS. 8 and 9, the coefficient K2 of the multiplying circuit 6 is changed according to the color temperature of the light source and the aperture value, as in the embodiment shown in FIGS. You may do so.

[0046]

As described above, according to the present invention,
Even in a color solid-state imaging device having a single image sensor, it is possible to obtain luminance reproduction equivalent to that of a three-channel process color solid-state imaging device, and to obtain luminance reproduction faithful to a subject.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an imaging device according to the present invention.

FIG. 2 is a block diagram showing a specific example of a signal processing circuit and a luminance signal generation circuit in FIG.

FIG. 3 is a block diagram showing another embodiment of the imaging apparatus according to the present invention.

FIG. 4 is a block diagram showing still another embodiment of the imaging apparatus according to the present invention.

FIG. 5 is a block diagram showing still another embodiment of the imaging device according to the present invention.

FIG. 6 is a block diagram showing still another embodiment of the imaging apparatus according to the present invention.

FIG. 7 is a block diagram showing still another embodiment of the imaging apparatus according to the present invention.

FIG. 8 is a block diagram showing still another embodiment of the imaging device according to the present invention.

FIG. 9 is a block diagram showing still another embodiment of the imaging apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor 2 Signal processing circuit 3 Luminance signal generation circuit 4 Arithmetic circuit 5 Core circuit 6 Multiplication circuit 7, 8 Addition circuit 9 Color signal generation circuit 10 White balance processing circuit 11 Addition circuit 12 Color difference matrix circuit 13 Encoding circuit 25 Addition circuit 26 White balance control circuit 27 Color temperature detection circuit 28 Coefficient circuit 30 Aperture 31 Aperture control circuit 32 Coefficient circuit 33, 34 Gamma circuit 35, 36 Addition circuit 37 LPF circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-173287 (JP, A) JP-A-63-158990 (JP, A) JP-A-62-171393 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) H04N 9/73 H04N 9/04

Claims (4)

(57) [Claims] An image pickup unit having a single image pickup device provided with a plurality of color separation filters having different spectral sensitivities, and an output unit configured to output a signal including a color component corresponding to each of the color separation filters; A color signal processing circuit that generates a primary color signal from the color component corresponding to the color separation filter of the output signal of the imaging unit; a white balance processing circuit that corrects the white balance of the primary color signal; A first luminance signal processing circuit for processing the signal to generate a first luminance signal; and processing the primary color signal white balance corrected by the white balance processing circuit to obtain a low-frequency signal of the first luminance signal. A second luminance signal processing circuit for generating a second luminance signal in a frequency band substantially equal to the component; and a subtraction detecting a difference signal between the second luminance signal and the low frequency component of the first luminance signal. Circuit and the difference A core circuit for removing a signal component of a predetermined level or less from the minute signal; and an output signal of the core circuit having a predetermined ratio with the low frequency component of the first luminance signal. An image pickup apparatus comprising: an addition circuit that adds the luminance signal to one luminance signal. 2. The red signal output from the white balance processing circuit according to claim 1,
And the blue signal and the output from the second luminance signal processing circuit.
And a second luminance signal to generate a color difference signal.
And a color difference signal output from the color difference matrix circuit.
Of the primary color signal in the white balance processing circuit.
A white balance control circuit for controlling a gain, and a color temperature detecting circuit for detecting a color temperature of a light source for irradiating a photographing subject from the gain controlled by the white balance control circuit.
And road, and a multiplication circuit for multiplying a coefficient corresponding to the detection result of the color temperature detection circuit to an output signal of said core circuit is provided, said adder circuit and an output signal and said first luminance signal of multiplication circuit An imaging apparatus comprising: adding the low frequency component of the first luminance signal and the second luminance signal at a ratio based on the coefficient. 3. An apparatus according to claim 1, further comprising: an aperture value detecting means for detecting an aperture value of the lens; and a multiplying circuit for multiplying an output signal of said core circuit by a coefficient corresponding to a detection result of said aperture value detecting means. The addition circuit adds the output signal of the multiplication circuit and the first luminance signal, so that the low-frequency component of the first luminance signal and the second luminance signal at a ratio based on the coefficient. And an image pickup device. 4. The first gamma circuit according to claim 1, 2 or 3, wherein the first gamma circuit performs gamma processing on the primary color signal white-balance corrected by the white balance processing circuit, and the first gamma circuit performs gamma processing on the first luminance signal. And a second gamma circuit, wherein the second luminance signal processing circuit generates the second luminance signal from the primary color signal gamma-processed by the first gamma circuit, and wherein the subtraction circuit from the primary color signals gamma treated with 1 gamma circuit of the second of said second luminance signal and said first luminance signal gamma processing in a gamma circuit the second generated by the luminance signal processing circuit An imaging device, wherein a difference signal from the low frequency component is detected.