JP2001197510A - Solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup device that reduces a quantization error of color information to enhance the accuracy of color processing. SOLUTION: A gain of an AGC 6 amplifying an output signal from a color CCD 1 is selected differently in time division by taking an output difference from an output signal by each line (or each color component) into account synchronously with a line switching period of the output signal (or color component switching period) so as to reduce a quantization error in the convertion of the amplified output signal into a digital signal by an analog/digital converter 8. Or a reference voltage in the analog/digital converter 8 is switched to a different voltage set to each line (or each color component) in time division in place of the gain so as to apparently amplify the output signal. In the various color processing arithmetic operations such as digital filter processing and color matrix processing by a color processing block 10, the intensity of each color component is corrected in response to a ratio on a gain (or a reference voltage) by each line (or each color component).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a solid-state image pickup device for picking up a color image using a solid-state image pickup device having a plurality of color filters arranged on a surface thereof.

[0002]

2. Description of the Related Art Conventionally, for example, in a digital camera or a video camera using a CCD as an image pickup device, color filters are arranged in a mosaic or stripe shape on the surface of the CCD on which an optical image is formed. Thus, color information of a subject image is obtained using a CCD that can only obtain luminance information. The output signal (imaging signal) of the CCD is subjected to noise removal and amplification at the stage of an analog signal, is converted to a digital signal by quantization, and is subjected to various color processing such as digital filter processing and color matrix processing. By performing the calculation, an actual color image can be obtained.

On the other hand, CCs having color filters arranged
When D is used, the magnitude of the output signal from the CCD differs for each color due to the difference in spectral characteristics of each color filter. For example, considering the output value of a CCD that has passed white (W), green (G), cyan (Cy), and yellow (Ye) filters, W is the largest because no filter is applied, and W is the largest. Ye is the next largest and G is the smallest. That is, the data in the case where white light of the standard light source is imaged has a ratio of, for example, W: G: Cy: Ye = 586: 168: 366: 339.

For this reason, in general, when an actual color image is obtained by performing various color processing operations such as digital filter processing and color matrix processing on a CCD output signal, the output signal has a maximum value of W. A
By effectively using the quantization bit number (8 to 10) of / D, it is possible to prevent W from being saturated and being clipped up and down.

[0005]

However, when converting the output signal of the CCD having the above-described color filter into a digital signal, the number of A / D quantization bits (8 to 8) is required.
If we try to use 10) effectively for W, the accuracy of quantization of other colors will drop, and for the largest G, the accuracy will be 1 to
Two digits are lost. Conversely, if an attempt is made to use G effectively to prevent such loss of digits, other colors will be clipped (overflow), causing a reduction in color processing accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to provide a solid-state imaging device capable of reducing a quantization error of color information and improving the accuracy of color processing. And

[0007]

According to a first aspect of the present invention, there is provided a solid-state imaging device, comprising: amplifying an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface; After the converted output signal is converted to a digital signal, in a solid-state imaging device that performs color processing, the amplification factor of the output signal is synchronized with a switching period of each successive color component in the output signal, and Amplification factor switching means for switching to an amplification factor for each color component of a pair that is continuously determined based on a difference in spectral characteristics of each color of the filter; and, in the color processing, the intensity of each color component is continuously changed. For each pair of color components, a correction means for correcting based on the ratio between the corresponding amplification factor and another amplification factor is provided.

In such a configuration, at the time of quantization when converting the output signal of the solid-state image pickup device into a digital signal, one of the continuous paired color components included in the output signal is connected to another continuous color component. It is possible to effectively use the number of quantization bits while avoiding overflow and underflow, and preventing digit drop and rounding errors, both on the color component side forming the pair.

Further, in the solid-state imaging device according to the second aspect, after amplifying an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface, converting the amplified output signal into a digital signal, In a solid-state imaging device that performs color processing, a reference voltage that is a reference for quantization when converting the output signal into a digital signal is synchronized with a switching cycle of each successively paired color component in the output signal, Voltage switching means for switching to a voltage for each color component in a continuous pair determined on the basis of a difference in spectral characteristics for each color of the color filter; and, in the color processing, the intensity of each color component is continuously changed. Correction means for correcting each pair of color components based on the ratio between the corresponding reference voltage and another reference voltage.

[0010] Also in this configuration, at the time of quantization when converting the output signal of the solid-state image pickup device into a digital signal, one of the continuous paired color components included in the output signal and another continuous color component are included. It is possible to effectively use the number of quantization bits while avoiding overflow and underflow, and preventing digit drop and rounding errors, both on the color component side forming the pair.

According to a third aspect of the present invention, in the solid-state imaging device, after amplifying an output signal of the solid-state imaging device in which a plurality of color filters are arranged on the surface and converting the amplified output signal to a digital signal, In a solid-state imaging device that performs color processing, the amplification factor of the output signal is synchronized with a switching cycle of a color component in the output signal, and for each color component determined based on a difference in spectral characteristics of each color of the color filter. An amplification factor switching device for switching to an amplification factor, and a correction device for correcting the intensity of each color component based on the ratio of the corresponding amplification factor to another amplification factor during the color processing are provided.

In such a configuration, at the time of quantization when converting the output signal of the solid-state imaging device into a digital signal, overflow and underflow are avoided for every color component included in the output signal, and digit loss and digit loss are prevented. The number of quantization bits can be used effectively while preventing rounding errors.

According to a fourth aspect of the present invention, there is provided a solid-state imaging device, comprising: amplifying an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface; converting the amplified output signal into a digital signal; In a solid-state imaging device that performs color processing, a reference voltage serving as a reference for quantization when converting the output signal into a digital signal is synchronized with a switching cycle of a color component in the output signal, and the color filter is provided for each color of the color filter. Voltage switching means for switching to a voltage for each color component determined based on a difference in spectral characteristics; and, in the color processing, correcting the intensity of each color component based on a ratio between a corresponding reference voltage and another reference voltage. Correction means.

[0014] Also in such a configuration, at the time of quantization when converting the output signal of the solid-state imaging device into a digital signal, overflow and underflow are avoided for every color component included in the output signal, and digit loss and digit loss are prevented. The number of quantization bits can be used effectively while preventing rounding errors.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 2 is a block diagram illustrating a main part of the CCD camera according to the first embodiment of the present invention.

The CCD camera has a color CCD 1 provided with a color filter on a light receiving surface. Color C
The CD 1 is driven by a vertical signal generated by a vertical driver 3 based on a driving signal generated by a TG (CCD driving timing generator) 2 and a timing signal generated by the TG 2, and converts an analog image signal to an analog processing IC 4. Output. FIG. 2 is a diagram schematically illustrating the structure of the color CCD 1. The color CCD 1 includes a photosensitive unit 21, a storage unit 22, a transfer gate 23,
A horizontal shift register 24 and an output unit 25 are provided. The photosensitive portion 21 is a portion where an optical image is formed. The photosensitive portion 21 includes an imaging portion 21a on which a charge image is formed by photoelectric conversion and an optical black portion 21b around the imaging portion 21a. A color filter is mounted on the imaging portion 21a. ing. The color filter in the present embodiment is a complementary color mosaic type of four colors. In even lines (2i, 2i + 2,...), W filters and G filters are alternately arranged for each pixel, and odd lines (2i + 1, 2i + 3). ...), Cy filters and Ye filters are alternately arranged for each pixel.

When the color CCD 1 is driven, the photosensitive section 21
The signal charges of all pixels (for one screen) accumulated in the storage unit 2
After that, the data is sequentially sent to the horizontal shift register 24 via the transfer gate 23 line by line. When a pixel signal for one line is input to the horizontal shift register 24, the signal is transferred in the horizontal direction and output from the output unit 25, so that the image signal for each line in the horizontal direction is output at a constant period. It is sent to the processing IC 4. A dummy bit area 24a is provided at the head (left end in the figure) of the horizontal shift register 24,
There will be a signal blank between the odd line signal and the even line signal.

The analog processing I to which an image pickup signal is input
C4 is a CDS (correlated double sampling circuit) 5, an analog amplifier AGC (gain adjustment amplifier) 6,
A D / A converter 7 and a color CCD 1
The imaging signal sent from the A / D converter 8 is sent to the A / D converter 8 after being amplified by the AGC 6 after the characteristic reset noise or the like generated when the color CCD 1 is driven is removed by the CDS 5. The A / D converter 8 operates in synchronization with the timing signal sent from the TG 2 and is sent from the analog processing IC 4 on the basis of an analog reference voltage that has been divided into predetermined values by the resistors R1 to R3 and input. The imaging signal is quantized, that is, converted into a digital value for each pixel and output as a digital signal. The output digital signal is temporarily stored in a memory (for example, a D-RAM or the like) 9 as image data, read out in accordance with a memory control signal sent from a microcomputer 11 described later, and sent to a color processing block 10 at a subsequent stage. Can be The image data sent to the color processing block 10 is subjected to various color processing such as digital filter processing, color matrix processing and the like, and finally stored as a compressed video signal, or a digital video signal or analog video signal. Generated on the signal.

The drive signal generated by the TG2,
The gain of C6 is controlled by the microcomputer 11.
The microcomputer 11 includes a CPU 12, a ROM 13 storing an operation program thereof, and a RAM 1 serving as a working memory.
4 etc., and operates in accordance with the above operation program, and
Control the CD camera. For example, in the automatic exposure control, the charge accumulation time (exposure time) of the color CCD 1 and the like are controlled by controlling the TG 2 based on the luminance signal sent from the color processing block 10. Sends a gain setting signal to the AGC 6
The gain of the imaging signal in the GC 6 is adjusted.

Further, the ROM 13 stores gain setting data d1 as shown in FIG. This data is data indicating a gain which is a reference of the AGC 6 when the color CCD 1 is driven, and is a color CCD.
It is composed of an even line and an odd line in one photosensitive section 21 and a gain corresponding thereto. Each gain (g
ain (W, G) and gain (Cy, Ye)) are determined by the difference between the sensitivity of the color CCD 1 and the spectral characteristics of the color filter described above. , The gain in accordance with the signal level on the W side is set so that the output value of the signal on the W side is not saturated. The odd line gain ga
in (Cy, Ye) includes the gain gain of the even-numbered line.
(W, G) is a predetermined coefficient, “5/3” in the present embodiment.
Is set.

The microcomputer 11 controls the operation of the AGC 6 and the color processing block 10 in accordance with the operation program and the gain setting data d1, thereby providing the amplification factor switching means of the present invention. Function as correction means. That is, when the color CCD 1 is driven, the gain setting signal to be sent to the AGC 6 is periodically switched in synchronization with the line switching timing (the switching period for each color component forming a continuous pair), as shown in FIG. , The gain of the even-numbered line (2i, 2i + 2,...)
G), the gains of the odd lines (2i + 1, 2i + 3,...) Are controlled to gain (Cy, Ye). Therefore, the imaging signal output from the analog processing IC 4 is converted to A /
When quantization is performed by the D converter 8, the number of quantization bits can be effectively used while minimizing digit drop and rounding errors for the color components of Cy and Ye.

Note that the gain switching timing in the present embodiment is set immediately after all pixel signals a corresponding to the image pickup unit 21a of each line signal are output from the color CCD 1 (output unit 25) (corresponding to the optical black unit 21b). Immediately before the pixel signal b is output), and the switching frequency is about several kHz to several tens of kHz. The gain set by such control is a basic gain as described above. For example, the gain adjustment associated with the automatic exposure control described above is performed based on the gain set by the above control.

When the image data read from the memory 9 is subjected to various color processing operations such as digital filter processing and color matrix processing by the color processing block 10, the microcomputer 11 performs one of the operation steps. In step (1), the color components of Cy and Ye are corrected using the above-described coefficients, that is, the color processing block 10 performs a correction process of increasing the color components of Cy and Ye by 3/5.

Therefore, in this embodiment, A
The quantization error of the color information when the image signal is quantized by the / D converter 8 can be reduced, and more accurate color processing can be performed. As a result, in a color image finally obtained, color reproducibility is improved, and differences in brightness can be expressed more finely. Moreover, this can be performed without changing the conventional hardware configuration.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described. In the present embodiment, in the CCD camera shown in FIG. 1, the above-described switching control of the gain of the AGC 6 for each line is eliminated (however, control relating to automatic exposure control and the like is performed), and the reference voltage of the A / D converter 8 is changed. Is switched for each line.

FIG. 5A is a block diagram showing the present embodiment and corresponds to the part A in FIG. 1, and an analog multiplexer 31 is connected to the A / D converter 8. On the input side of the analog multiplexer 31, resistors R1a to R3a and R1b to R3b for supplying two different reference voltages to the A / D converter 8 for even and odd lines.
Is connected. The resistance values of the A / D converter 8
Is set in advance to a value that is narrowed to the reciprocal multiple of the gain setting coefficient described in the first embodiment. That is, the reference voltage value for the odd line divided by the resistors R1b to R3b is equal to the resistance R
It is set to be 3/5 times the reference voltage value for the even-numbered line divided by 1a to R3a.
The control line of the analog multiplexer 31 is TG
2 are connected. TG2 is a voltage switching means of the present invention, and sends a reference voltage switching signal synchronized with the line switching timing in the output signal of the color CCD 1 to the analog multiplexer 31. The other configuration is the same as that of the first embodiment.

In this embodiment, as shown in FIG. 6, the TG 2 outputs a reference voltage switching signal to the analog multiplexer 31 and the output signal of the analog processing IC 4 outputs an even line (2i, 2i + 2,...). It is set to "0" while the output signal is a signal of "1" while the output signal is a signal of an odd line (2i + 1, 2i + 3,...). Accordingly, the analog multiplexer 3
1, when the reference voltage switching signal is "0", the reference voltage divided by the resistors R1a to R3a is set to A /
When the switching signal is "1", the reference voltage divided by the resistors R1b to R3b is supplied to the A / D converter 8.
It is supplied to the converter 8 (see FIG. 5B). This allows
When the image signal of the odd lines (2i + 1, 2i + 3,...), That is, the image signal composed of the color components of Cy and Ye is quantized for each pixel, the apparent output is amplified by a factor of 5/3. As a result, the number of quantization bits can be used effectively. Further, the microcomputer 11 causes the color processing block 10 to perform the same correction processing as in the first embodiment.

Thus, in the present embodiment, A
The quantization error of the color information when the image signal is quantized by the / D converter 8 can be reduced, and more accurate color processing can be performed. In the present embodiment, since the reference voltage for quantizing the imaging signal is set by the voltage dividing resistor, the above-described resistor R1b is used.
By changing the resistance values of R3b to R3b, the amplification factor when amplifying the apparent output of the imaging signal during quantization can be adjusted in an analog manner. Therefore, an output higher than the apparent output of the imaging signal can be more accurately made to correspond to the difference in the spectral characteristics of the color filters, and more accurate color processing can be performed.

In this embodiment, the TG 2 constitutes the voltage switching means of the present invention, and the TG 2 supplies a reference voltage switching signal to the analog multiplexer 31. May be output. In the first and second embodiments described above, the arrangement order of the color components in the output signal of the color CCD 1 matches the arrangement order of the respective colors of the color filters in the imaging section 21a of the color CCD 1 in the horizontal direction. In this example, the gain of the AGC 6 and the reference voltage of the A / D converter 8 are switched in synchronization with the switching timing of the line in the output signal of the color CCD 1. Even if the order of the colors of the color filters does not match the horizontal order, the gain of the AGC 6 and the reference voltage of the A / D converter 8 are not changed by the color CCD 1.
A similar effect can be obtained by switching in synchronism with the switching cycle of each color component that forms a continuous pair in the output signal of FIG.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
An embodiment will be described. In this embodiment, FIG.
In the CCD camera having the same configuration as that shown in FIG. 1, the readout method of the image signal in the color CCD 1 is different from that of the first embodiment, and the ROM 13 has a readout method different from that of the first embodiment. Microcomputer 1
1 and the gain setting data.

That is, the color CC in the present embodiment
D1 is a horizontal dual readout method in which color filters of the same color are grouped at the time of driving and are divided into even-numbered rows and odd-numbered rows in a zigzag and rearranged in subsequent blocks. ...)
W, W, W,... W, G, G, G,.
In odd lines (2i + 1, 2i + 3,...), C
y, Cy, Cy,... Cy, Ye, Ye, Ye,.
-Ye. That is, the color components are switched at a frequency 2fl, which is twice the line switching frequency fl (see FIG. 8).

The ROM 13 stores gain setting data d2 as shown in FIG. This data is data indicating the reference gain of the AGC 6 when the color CCD 1 is driven, as in the first embodiment, and is determined by the difference between the sensitivity of the color CCD 1 and the spectral characteristics of the color filter described above. Gain (gain (W), gain) for each filter color (color component)
(G), gain (Cy), and gain (Ye)). Gain (W) is color C
The values are set according to the sensitivity of CD1, and the other values are: gain (G) = about 3.5 × gain (W) gain (Cy) = about 1.6 × gain (W) gain (Ye) = approximately 1.7 × gain (W).

The microcomputer 1 according to the present embodiment
1 operates as follows according to the operation program stored in the ROM 13 and the gain setting data d2. That is, the gain setting signal to be sent to the AGC 6 is switched at a switching frequency of 2fl in synchronization with the switching timing of the color component in the imaging signal, whereby the gain of the AGC 6 is set to gain (W) and gain (G) as shown in FIG. ,
The control is repeatedly performed in the order of gain (Cy) and gain (Ye). Also, the color processing block 10 stores the memory 9
When various color processing operations such as digital filter processing and color matrix processing are performed on the image data read from the image data, the coefficients (“3.5”, “1. 6 "and" 1.7 ") to perform a correction process on each color component (G, Cy, Ye).
That is, a correction process for making each color component a reciprocal multiple of the coefficient is performed.

Therefore, in the present embodiment, when the image signal output from the analog processing IC 4 is quantized by the A / D converter 8, the G, Cy, and Ye color components are subjected to digit skipping and rounding. While minimizing errors,
The number of quantization bits can be used effectively. For this reason, more accurate color processing is performed to reduce the quantization error of color information when quantizing an image signal than that described in the first and second embodiments described above. Can be.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
An embodiment will be described. In the present embodiment, the third
In the CCD camera according to the second embodiment, the above-mentioned gain switching control for each color of the AGC 6 is eliminated (however, control relating to automatic exposure control and the like is performed), and an A / D converter is used similarly to the second embodiment. 8 is switched for each color.

FIG. 9A is a block diagram showing the present embodiment and corresponds to the portion A in FIG. 1. The output side of the analog multiplexer 41 is connected to the A / D converter 8. On the input side of the analog multiplexer 41, resistors R1a to R3a (for W) and R1b to supply a reference voltage for each color (W, G, Cy, Ye) to the A / D converter 8.
R3b (for G), R1c-R3c (for Cy), R1d-
R3d (for Ye) is connected. These resistance values are set in advance to values that narrow the reference voltage for each color to the reciprocal multiple of the gain coefficient described in the third embodiment. That is, the value of each resistor is such that the reference voltage value for G by the voltage division of the resistors R1b to R3b is 1 / 3.5 times the reference voltage value for W divided by the resistors R1b to R3b, and similarly for Cy. Reference voltage value is 1
/1.6 times, the reference voltage value for Ye is 1 / 1.7
It is set to double.

The analog multiplexer 41 is connected to the TG 2 by two control lines. The analog multiplexer 41 has a line switching signal synchronized with the line switching timing in the output signal of the color CCD 1 and a color in the imaging signal. A color switching signal synchronized with the component switching timing is transmitted from TG2. The switching frequency of the color switching signal is twice the line switching frequency, and the other configuration is the same as that of the third embodiment.

In this embodiment, FIG.
As shown in, the TG 2 outputs a line switching signal and the output signal of the analog processing IC 4 outputs an even line (2i, 2i + 2,
..), The signal is set to “0” and the odd-numbered line (2
(i + 1, 2i + 3,...)
And At the same time, the color switching signal is transmitted to the analog processing IC 4
Is "0" while the output signal is a signal of W component and Cy component, and "1" while it is a signal of G component and Ye component.
And Accordingly, the analog multiplexer 41
While the output signal of the analog processing IC 4 is a signal of the W component, the reference voltage for W divided by the resistors R1a to R3a is supplied to the A / D converter 8, and while the signal is of another color. Sets the corresponding reference voltage for each color to A /
It is supplied to the D converter 8. (See FIG. 9B). As a result, when the imaging signal composed of the G, Cy, and Ye color components is quantized for each pixel, the apparent output is amplified to be equal to the imaging signal composed of the W color component. The number of quantization bits can be effectively used for the color component of. Further, the microcomputer 11 causes the color processing block 10 to perform the same correction processing as in the third embodiment.

Thus, also in the present embodiment, when the image signal output from the analog processing IC 4 is quantized by the A / D converter 8, the number of quantization bits for each of the G, Cy, and Ye color components Can be used effectively. For this reason, more accurate color processing is performed to reduce the quantization error of color information when quantizing an image signal than that described in the first and second embodiments described above. Can be. In the present embodiment, since the reference voltage for quantizing the imaging signal is set by the voltage dividing resistor, the above-described resistor R1a is used.
R3a (for W), R1b to R3b (for G), R1c
By changing the resistance values of R3c (for Cy) and R1d to R3d (for Ye), the amplification factor when amplifying the apparent output of the imaging signal during quantization can be adjusted in an analog manner. Therefore, as compared with the third embodiment, the apparent output of the imaging signal can be made to more accurately correspond to the difference in the spectral characteristics of the color filters, and more accurate color processing can be performed.

In the present embodiment, the TG2 constitutes the voltage switching means of the present invention and supplies the line switching signal and the color switching signal from the TG2 to the analog multiplexer 41. The signal may be supplied from the microcomputer 11.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.
An embodiment will be described. In this embodiment, FIG.
In a CCD camera having a configuration similar to that shown in FIG. 1, a three-color stripe type color filter in which Ye, Cy, and G color filters are sequentially arranged in an imaging unit 21a as shown in FIG. This is provided with a color CCD 51 on which a filter is mounted. Color C
Since the other structure of the CD 51 is the same as that shown in FIG. 1, the same reference numerals are given and the description is omitted.

The readout method of the image pickup signal in the color CCD 51 is a horizontal multi-readout method in which color filters of the same color are grouped at the time of driving, divided in a zigzag and rearranged in subsequent blocks, and the image pickup signal is In the line, Ye, Ye, Ye, ..., Ye, Cy,
Cy, Cy,... Cy, G, G, G,. That is, the color components are switched at a frequency 3fl, which is three times the line switching frequency fl (see FIG. 12). Further, similarly to the third embodiment, the ROM 13 stores gain setting data indicating a gain serving as a reference of the AGC 6 when the color CCD 51 is driven (not shown). Note that the gain setting data of the present embodiment includes three types of gains corresponding to the three colors of Ye, Cy, and G, gain (Ye), gain (Cy), and g.
ain (G), and the value of each gain is a color CCD
A value obtained by multiplying a value set according to the sensitivity of 1 by a predetermined coefficient.

Further, the microcomputer 11 performs the third operation in accordance with the operation program stored in the ROM 13 and the gain setting data.
12, the gain of the AGC 6 is set to gain (Ye), gain,
Switching control is repeatedly performed in the order of (Cy) and gain (G). When the color processing block 10 performs various color processing operations such as digital filter processing and color matrix processing on the image data read from the memory 9, the above-described coefficient , A correction process for each color component (G, Cy, Ye) is performed. That is, a correction process for making each color component a reciprocal multiple of the coefficient is performed. Therefore, in the present embodiment, the same effect as in the third embodiment can be obtained.

In this embodiment and the first and second embodiments described above.
In the third embodiment, the gain value set in the AGC 6 for each line or each color component, that is, the setting data is R
Although the data stored in the OM 13 is shown, the setting data may be stored in another data rewritable storage device other than the ROM 13 such as an EEP-ROM. Further, in the above description, when the microcomputer 11 performs the gain adjustment associated with the automatic exposure control or the like, the description will be made assuming that the gain adjustment is performed based on the gain set by the control according to the present invention described above. However, in addition to this, the ROM 13 or the like stores a magnification coefficient for each line or each color component determined by the difference in spectral characteristics of the color filter, and a gain already set by the magnification coefficient, for example, The configuration may be such that the gain set by the gain adjustment accompanying the automatic exposure control or the like is periodically changed. In that case,
When the microcomputer 11 causes the color processing block 10 to perform processing for correcting the intensity of each color component during various color processing calculations, the above-described magnification coefficient (setting data) can be used as a calculation parameter.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.
An embodiment will be described. In the present embodiment, the fifth
In the CCD camera of the embodiment, the AGC
6 is eliminated (however, control relating to automatic exposure control and the like is performed), and the reference voltage of the A / D converter 8 is changed for each color similarly to the second and fourth embodiments. Switching.

FIG. 13A shows the present embodiment.
FIG. 2 is a configuration diagram corresponding to a portion A of FIG. 1, and an output side of an analog multiplexer 61 is connected to the A / D converter 8.
On the input side of the analog multiplexer 61, resistors R1a to R3a (for Ye) and R1b to supply a reference voltage for each color (Ye, Cy, G) to the A / D converter 8.
R3b (for Cy) and R1c to R3c (for G) are connected. These resistance values are set in advance to values that narrow the reference voltage of each color to the reciprocal of the above-described coefficient of the gain described in the fifth embodiment. The analog multiplexer 61 is connected to the TG2 by two control lines.
Is connected to the analog multiplexer 61.
A first color switching signal and a second color switching signal synchronized with the line switching timing in the output signal of the color CCD 51 are sent from the TG 2.
The first and second color switching signals are signals in which a pulse is output only for 1/3 of one cycle, and have a phase difference of 1/3 cycle between them.

In this embodiment, FIG.
TG2 sets the first color switching signal to "1" only while the output signal of the analog processing IC 4 is a G component signal, and the output signal of the analog processing IC 4 is C
The second color switching signal is set to “1” only while the signal is a y-component signal. Accordingly, the analog multiplexer 6
1 indicates that the color component of the output signal of the analog processing IC 4 is Ye,
Each time switching is performed in the order of Cy and G, the reference voltage supplied to the A / D converter 8 is switched to a correspondingly divided reference voltage (see FIG. 13B). Thus, when the image signal composed of Ye, Cy, and G color components is quantized for each pixel, the apparent output is amplified in the same manner as in the fifth embodiment. The number of quantization bits can be effectively used for the component. Further, the microcomputer 11 causes the color processing block 10 to perform the same correction processing as in the fifth embodiment.

Thus, also in the present embodiment, when the image signal output from the analog processing IC 4 is quantized by the A / D converter 8, the number of quantization bits for each of the Ye, Cy, and G color components Can be used effectively. Therefore, as in the fifth embodiment, more accurate color processing can be performed by reducing the quantization error of color information when quantizing an imaging signal. Further, in the present embodiment, since the reference voltage for quantizing the image signal is set by the voltage dividing resistor, the apparent output of the image signal is amplified at the time of quantization by changing the value of the resistor used therefor. The amplification factor can be adjusted in an analog manner. Therefore, as compared with the fifth embodiment, the apparent output of the imaging signal can be made to more accurately correspond to the difference in the spectral characteristics of the color filters, and more accurate color processing can be performed.

In this embodiment, the TG2 constitutes the voltage switching means of the present invention, and the TG2 supplies the first and second color switching signals to the analog multiplexer 61. These signals are sent to the microcomputer 1
1 may be supplied. In each of the embodiments described above, the solid-state imaging device of the present invention
Although the CCD camera provided with the color CCDs 1 and 51 is shown, the same effects as those described above can be obtained by applying the present invention to another solid-state imaging device having a solid-state imaging device other than the color CCDs 1 and 51.

[0050]

As described above, in the solid-state imaging device according to the first and second aspects, when the output signal of the solid-state imaging device is quantized at the time of conversion into a digital signal, any one of the Quantization on both the color component side that makes a continuous pair and the color component side that makes another pair, avoiding overflow and underflow, and preventing digit drop and rounding errors The number of bits can be used effectively. Therefore, it is possible to reduce the quantization error of the color information in units of the color components that form a continuous pair included in the output signal, and to improve the accuracy of the color processing. As a result, it is possible to improve the reproducibility of colors in a captured final color image and the ability to accurately represent small differences in brightness.

Further, in the solid-state imaging device according to the third and fourth aspects, at the time of quantization when converting the output signal of the solid-state imaging device into a digital signal, overflow occurs for every color component included in the output signal. It is now possible to effectively use the number of quantization bits while avoiding underflow and underflow, and preventing errors such as loss of digits and rounding. Therefore, the quantization error of all color information can be reduced, and the accuracy of color processing can be improved.
As a result, it is possible to improve the reproducibility of colors in a captured final color image and the ability to accurately represent small differences in brightness.

[Brief description of the drawings]

FIG. 1 is a block diagram of an analog processing unit of a CCD camera according to a first embodiment of the present invention.

FIG. 2 is a schematic structural view of a CCD.

FIG. 3 is a schematic explanatory view showing gain setting coefficient data stored in a ROM.

FIG. 4 is a diagram showing switching timing of gain.

FIG. 5 is a diagram showing a second embodiment of the present invention,
2A is a configuration diagram corresponding to a portion A in FIG. 1, and FIG. 2B is an operation explanatory diagram of an analog multiplexer.

FIG. 6 is a diagram showing switching timing of a reference voltage.

FIG. 7 is a schematic diagram illustrating gain setting coefficient data stored in a ROM according to a third embodiment of the present invention.

FIG. 8 is a diagram showing the timing of switching the gain in the embodiment.

FIG. 9 is a view showing a fourth embodiment of the present invention,
2A is a configuration diagram corresponding to a portion A in FIG. 1, and FIG. 2B is an operation explanatory diagram of an analog multiplexer.

FIG. 10 is a timing chart in the embodiment.

FIG. 11 is a schematic structural view of a CCD showing a fifth embodiment of the present invention.

FIG. 12 is a diagram showing gain switching timing in the embodiment.

13A and 13B are diagrams showing a sixth embodiment of the present invention, wherein FIG. 13A is a configuration diagram corresponding to a portion A in FIG. 1, and FIG. 13B is an operation explanatory diagram of an analog multiplexer.

FIG. 14 is a diagram showing a reference voltage switching timing in the embodiment.

[Explanation of symbols]

 1,51 color CCD 2 TG 4 analog processing IC 6 AGC 8 A / D converter 9 memory 10 color processing block 11 microcomputer 31,41,61 analog multiplexer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C065 AA01 AA03 BB07 CC02 CC03 CC08 CC09 DD02 DD17 EE05 EE08 GG03 GG18 GG30 GG31 GG32

Claims (4)

[Claims] 1. A solid-state imaging device that amplifies an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface, converts the amplified output signal into a digital signal, and performs color processing. Is synchronized with the switching period of each successive color component in the output signal, and for each successive pair of color components determined based on the difference in spectral characteristics of each color of the color filter. Amplification factor switching means for switching to the amplification factor of, the intensity of each color component in the color processing,
A solid-state imaging device comprising: a correction unit that corrects, based on a ratio of a corresponding amplification factor to another amplification factor, for each of the color components forming a continuous pair. 2. A solid-state imaging device that amplifies an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface, converts the amplified output signal into a digital signal, and performs color processing. Is converted into a digital signal, a reference voltage that is a reference for quantization is synchronized with a switching cycle of each color component that forms a continuous pair in the output signal, and a difference in spectral characteristics of each color of the color filter is obtained. Voltage switching means for switching to a voltage for each color component in a continuous pair determined on the basis of the intensity of each color component during the color processing,
A solid-state imaging device comprising: a correction unit that corrects, based on a ratio between a corresponding reference voltage and another reference voltage, for each of the color components that form a continuous pair. 3. A solid-state imaging device that amplifies an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface, converts the amplified output signal into a digital signal, and performs color processing. Amplification factor switching means for switching the amplification factor of the color signal to an amplification factor of each color component determined based on a difference in spectral characteristics of each color of the color filter in synchronization with a switching cycle of a color component in the output signal; and A solid-state imaging device comprising: correction means for correcting the intensity of each color component based on the ratio of the corresponding amplification factor to another amplification factor during processing. 4. A solid-state imaging device that amplifies an output signal of a solid-state imaging device having a plurality of color filters arranged on a surface, converts the amplified output signal into a digital signal, and performs color processing. Is converted into a digital signal, a reference voltage serving as a reference for quantization is synchronized with the switching cycle of the color component in the output signal, for each color component determined based on a difference in spectral characteristics of each color of the color filter. Voltage switching means for switching to a voltage of
A solid-state imaging device comprising: a correction unit configured to perform correction based on a ratio between a corresponding reference voltage and another reference voltage.