JP4123210B2 - Imaging device - Google Patents

Description

  The present invention relates to an image pickup apparatus that includes a solid-state image pickup device that includes a plurality of types of color filters and outputs color signals, and particularly relates to an image pickup apparatus that performs white balance processing of color signals.

  Conventionally, in a solid-state imaging device that performs a linear conversion operation that linearly converts the amount of incident light, its dynamic range is as narrow as two orders of magnitude, so when imaging a subject that constitutes a luminance distribution in a wide luminance range, other than the dynamic range The luminance information in the range is not output. Further, as a conventional solid-state imaging device, there is one that performs a logarithmic conversion operation for logarithmically converting the amount of incident light (see Patent Document 1). In this solid-state imaging device, the dynamic range is as wide as 5 to 6 digits. Therefore, even if an image of a subject constituting a luminance distribution in a slightly wide luminance range is captured, all luminance information in the luminance distribution is converted into an electrical signal. Can be output. However, since the imageable area becomes wider with respect to the luminance distribution of the subject, an area without luminance data is formed in the low luminance area or the high luminance area in the imageable area. On the other hand, the present applicant has proposed what can switch between the above-described linear conversion operation and logarithmic conversion operation (see Patent Document 2).

In addition, when a color image is picked up by providing a color filter in an image pickup apparatus equipped with these solid-state image pickup devices, the spectral distribution of the light source at the time of shooting and the transmittance of the color filter differ, so that the photoelectric conversion of each color signal The characteristics will be different. Therefore, in an imaging apparatus that captures such a color image, white balance processing is performed to match the photoelectric conversion characteristics of the color signals. In view of this, the present applicant has proposed an imaging apparatus that performs white balance processing in a white balance processing circuit based on a color temperature detected by a color temperature detection circuit in an imaging apparatus including a solid-state imaging device that performs a logarithmic conversion operation. (See Patent Document 3). In addition, the present applicant has proposed an imaging apparatus that performs white balance processing by switching an offset voltage when performing AD conversion in an AD converter in an imaging apparatus including a solid-state imaging device that performs a logarithmic conversion operation ( (See Patent Document 4).
JP-A-11-313257 JP 2002-77733 A JP 2002-10275 A JP 2002-290980 A

  However, the imaging devices in Patent Literature 3 and Patent Literature 4 are effective for white balance correction of an image signal output from a solid-state imaging device that performs a photoelectric conversion operation using only logarithmic conversion characteristics. A white balance cannot be achieved for a solid-state imaging device that performs a photoelectric conversion operation based on characteristics. Therefore, when using a solid-state imaging device capable of automatically switching between logarithmic conversion characteristics and linear conversion characteristics as in Patent Document 2, in white balance processing only for multiplication / division or addition / subtraction like conventional white balance processing, Cannot get enough white balance.

  In view of such a problem, when the present invention includes a solid-state imaging device including a plurality of regions whose photoelectric conversion characteristics are different from each other, white balance is accurately applied to a signal output by any characteristics. An object is to provide an imaging device capable of performing processing.

In order to achieve the above object, the imaging apparatus of the present invention has a first region in which an output signal changes with a first characteristic with respect to an incident light amount, and an output signal is different from the first characteristic with respect to the incident light amount. A solid-state imaging device including a pixel having a photoelectric conversion characteristic including a second region that changes in accordance with the second characteristic and provided with a plurality of types of color filters, and each type of the color filter output from the solid-state imaging device And a white balance circuit that performs white balance processing on the color signal of the color signal, wherein the white balance circuit has a signal level in which a shift between the color signals is corrected with respect to a level of the input color signal Is provided as output data, and the first lookup table is associated with both the first and second characteristics.

  In such an imaging apparatus, when a plurality of types of color signals are output from the solid-state imaging device, the white balance circuit refers to the first look-up table and achieves both the first and second characteristics. A signal level that is correlated and corrected for deviation between the color signals is obtained as output data. Then, this signal level is output to a subsequent circuit as a signal level after white balance processing.

  The first characteristic is, for example, a linear change with respect to the amount of incident light, and the second characteristic is, for example, a natural logarithmic change with respect to the amount of incident light.

  When one of the plurality of types of color signals is used as a reference first color signal and a color signal other than the reference color signal is used as a second color signal, the first look-up table includes the second color signal. The signal level can be used as an input address, and the signal level when the photoelectric conversion characteristic of the second color signal is converted into the photoelectric conversion characteristic of the first color signal can be used as output data for the input address.

  The white balance circuit includes a second look-up table having the signal level of the first color signal as an input address and the signal level subjected to gradation conversion processing as output data for the input address. The first look-up table converts the photoelectric conversion characteristic in the second color signal into the photoelectric conversion characteristic of the first color signal and uses the signal level on which the gradation conversion process has been performed as the data of the input address In addition to the white balance processing, gradation conversion processing for converting to gradation characteristics in a reproduction output device that reproduces and outputs γ characteristics and the like may be performed.

  In these imaging devices, an evaluation value representing the relationship between the photoelectric conversion characteristics of the first color signal and the photoelectric conversion characteristics of the second color signal is input from the solid-state imaging device for each type of the second color signal. And an evaluation value detection circuit for detecting from the relationship between the signal levels of the first color signal and the second color signal, and the first look-up table has a photoelectric conversion characteristic of the evaluation value and the first color signal. You may make it produce | generate based on. In the photoelectric conversion characteristics of the first color signal and the second color signal, the evaluation value is a difference in luminance value that serves as a boundary between the area that changes in the first characteristic and the area that changes in the second characteristic. Can be due to.

  In the evaluation value detection circuit, for each type of the second color signal, the evaluation is performed based on a relationship between an average value of each of the first color signal and the second color signal given from the solid-state imaging device. A value can be determined. At this time, the luminance values for the average values of the first color signal and the second color signal may be equal.

  In the evaluation value detection circuit, for each type of the second color signal, the first color signal and the second color changed with the first characteristic with respect to the incident light amount given from the solid-state imaging device. Based on the relationship between the average values of the signals, a first evaluation value is obtained, and the first color signal and the second color signal changed with the second characteristic with respect to the amount of incident light applied from the solid-state imaging device. Based on the relationship between the average values of the color signals, a second evaluation value is obtained, and the first evaluation value and the second evaluation value are weighted to add the photoelectric conversion characteristics of the first color signal and the first evaluation value. You may make it obtain | require the evaluation value showing the relationship of the photoelectric conversion characteristic of a two-color signal. At this time, the luminance values with respect to the average values of the first color signal and the second color signal at the time of obtaining the first evaluation value and the second evaluation value may be the same.

  In this way, when the evaluation value is obtained by weighted addition of the first evaluation value and the second evaluation value, a weighting factor may be set from the outside. Further, based on the relationship between the number of pixels that output a signal that changes with the first characteristic with respect to the incident light amount and the number of pixels that outputs a signal that changes with the second characteristic with respect to the incident light amount, A weighting factor in weighted addition may be set. At this time, the weight coefficient may be set for each type of the color signal. In addition, the number of pixels that output a signal that has changed with the first characteristic with respect to the incident light amount in the region centered on the main subject detected by the autofocus function, and the second characteristic with respect to the incident light amount. The weighting factor may be set based on the relationship with the number of pixels that output a signal.

  In the imaging apparatus described above, for each of the color signals, a signal level serving as a boundary between the first area and the second area determined by a dynamic range of the solid-state imaging element is constant, and the first area Based on the signal level that becomes the boundary of the second region, it is possible to distinguish between a signal that has changed in the first characteristic with respect to the incident light amount and a signal that has changed in the second characteristic with respect to the incident light amount. .

  The photoelectric conversion characteristic of the second color signal may be determined based on the photoelectric conversion characteristic of the first color signal and the evaluation value.

  In the above-described imaging device, after obtaining the luminance value for each signal level of the second color signal based on the photoelectric conversion characteristics of the second color signal, the signal level for each obtained luminance value is set to the first color. The first look-up table can be generated by obtaining the output data for the input address based on the photoelectric conversion characteristics of the signal.

  A plurality of types of photoelectric conversion characteristics of the first color signal may be stored in a memory, and the photoelectric conversion characteristics of the first color signal may be read from the memory and used based on the set dynamic range of the solid-state imaging device. I do not care. At this time, the dynamic range of the solid-state imaging device may be set discretely according to the type of photoelectric conversion characteristic of the first color signal stored in the memory. In addition, when the dynamic range of the solid-state imaging device is set continuously, the set dynamic range based on the photoelectric conversion characteristics of the first color signal corresponding to the dynamic range before and after the set dynamic range. The photoelectric conversion characteristics of the first color signal may be set.

  The solid-state imaging device may be a single-plate solid-state imaging device in which a plurality of types of color filters are provided for each pixel, or a plurality of plates of a solid image including a plurality of imaging devices provided for each of the plurality of color filters. It may be an image sensor.

  According to the present invention, by using a look-up table, white balance processing is accurately performed with a simple configuration on a color signal output from a solid-state imaging device including a plurality of regions having different photoelectric conversion characteristics. It can be carried out. Further, by providing the evaluation value detection circuit, it is possible to detect the evaluation value for each color signal that can confirm the relationship between the color signals. Therefore, the parameters set for the lookup table can be easily obtained from the photoelectric conversion characteristics of the detected value and the reference color signal.

  Further, after obtaining an evaluation value for each of the color signal changed with the first characteristic with respect to the incident light quantity and the color signal changed with the second characteristic with respect to the incident light quantity, these evaluation values are weighted. By adding, by setting the evaluation value of each color signal, a more accurate evaluation value can be obtained. Therefore, the parameters set for the lookup table can be made with higher accuracy. Further, the weighted addition is performed based on the relationship between the number of pixels that output a signal that has changed with the first characteristic with respect to the incident light amount and the number of pixels that output the signal that has changed with the second characteristic with respect to the incident light amount. In order to set the weighting coefficient in, the parameter set for the lookup table can be set according to the luminance distribution of the imaged subject. Therefore, it is possible to perform white balance processing according to the luminance distribution of the imaged subject.

  Furthermore, by using the parameters of the look-up table as parameters including components for gradation conversion processing, the white balance circuit can perform white balance processing and gradation conversion processing on each color signal. . In addition, when the look-up table includes a component for gain adjustment processing, the white balance circuit can perform white balance processing and gain adjustment processing on each color signal. Thus, since the gradation conversion process or the gain adjustment process can be performed simultaneously in the white balance circuit, a circuit for newly performing the gradation conversion process and the gain adjustment process can be omitted. Therefore, the processing speed can be increased and the apparatus configuration can be simplified.

<Configuration of imaging device>
A configuration of an imaging apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating an internal configuration of the imaging apparatus.

  1 is output from an optical system 1 composed of a plurality of lenses, a solid-state image sensor 2 that converts an incident light amount of light incident through the optical system 1 into an electrical signal, and the solid-state image sensor 2. An amplifier 3 for amplifying the electric signal, an AD conversion circuit 4 for converting the electric signal amplified by the amplifier 3 into a digital signal, a black reference correction circuit 5 for setting a minimum level of the digital signal from the AD conversion circuit 4, An FPN correction circuit 6 that removes FPN (Fixed Pattern Noise) due to the sensitivity of each pixel of the solid-state imaging device 2 from the digital signal corrected by the black reference value in the black reference correction circuit 5, and the FPN correction circuit 6 An AE / WB evaluation value detection circuit 7 for detecting respective evaluation values for performing automatic exposure control (AE) and white balance (WB) from the digital signal from which FPN has been removed at Based on the WB control circuit 8 that performs correction for each color signal so that the color balance of the digital signal from which FPN is removed by the FPN correction circuit 6 is obtained, and the color signals of a plurality of adjacent pixels output from the WB control circuit 8. The color interpolation circuit 9 that interpolates each color signal, the color correction circuit 10 that corrects the hue of each color signal output from the color interpolation circuit 9 for each pixel by another color signal, and the color correction circuit 10 output the color signal. A gradation conversion circuit 11 that performs gradation conversion of a digital signal, a coring circuit 12 that performs processing such as edge enhancement on the digital signal output from the gradation conversion circuit 11, and an overall control unit 13 that controls each block An aperture control unit 14 for controlling the exposure amount by the aperture 1 a provided in the optical system 1, and a clock for supplying a clock for operation timing to the solid-state imaging device 2 and the AD conversion circuit 4. It includes a timing generating circuit 15, a.

  In the imaging apparatus configured as described above, when light is incident on the solid-state imaging device 2 having a different color filter for each pixel through the optical system 1, a photoelectric conversion operation is performed in each pixel. An analog signal that is a different color signal for each pixel is output. That is, as shown in FIG. 2, when a color filter having a Bayer array with RGB is provided in the solid-state imaging device 2, an R signal representing red is a color that becomes G from a pixel provided with an R color filter. A G signal representing green is outputted from the pixel provided with the filter, and a B signal representing blue is outputted from the pixel provided with the color filter B. As will be described later, in the solid-state imaging device 2, the luminance position at which the linear conversion operation and the logarithmic conversion operation are switched is changed by changing the drive condition by the overall control unit 13. As a result, the dynamic range of the solid-state imaging device 2 is changed. The dynamic range becomes wider as the switching point becomes the lower luminance side.

  The R signal, the G signal, and the B signal that are serially output from the solid-state imaging device 2 are amplified by the amplifier 3 and then converted into a digital signal by the AD conversion circuit 4. When the R signal, the G signal, and the B signal thus converted into the digital signal are supplied to the black reference correction circuit 5, based on the dynamic range data that is information on the size of the dynamic range supplied from the overall control unit 13. The black level that is the lowest luminance value is corrected to the reference value (0). That is, since the black level varies depending on the dynamic range of the solid-state imaging device 2, the signal level that becomes the black level is subtracted from the signal levels of the R signal, the G signal, and the B signal output from the AD conversion circuit 4. Thus, the reference value correction is performed.

  The FPN component is removed from the R signal, the G signal, and the B signal subjected to the black reference correction by subtracting the FPN component stored in the FPN correction circuit 6. This FPN component is an offset variation caused by a threshold variation of MOS transistors constituting each pixel in the solid-state imaging device 2. When extracting the FPN component, for each of the RGB signals, an offset based on the difference in transmittance of the color filter is subtracted from the image signal for each pixel output from the solid-state imaging device 2 during uniform light irradiation. At this time, the offset based on the transmittance of each color filter is determined by the average value of each RGB signal at the time of uniform light irradiation, and each average value is subtracted from the RGB signal at the time of uniform light irradiation. The FPN component of the pixel may be extracted. The R signal, G signal, and B signal from which the FPN component has been removed in this way are supplied to the AE / WB evaluation value detection circuit 7 and the WB control circuit 8.

  The AE / WB evaluation value detection circuit 7 calculates the average value distribution range of the luminance representing the luminance range of the subject by confirming the luminance value of the image signal composed of the given R signal, G signal, and B signal, It is sent to the overall control unit 13 as an AE evaluation value for setting the exposure amount. Based on this AE evaluation value, the overall control unit 13 controls the aperture of the diaphragm 1a, whereby the exposure amount is controlled. The AE / WB evaluation value detection circuit 7 confirms the respective luminance ratios and luminance differences from the given R, G, and B signals, and calculates a WB evaluation value that is a reference value for white balance. And sent to the overall control unit 13. The WB control circuit 8 performs white balance processing based on the WB evaluation value and dynamic range data given from the overall control unit 13 so that the R signal, the G signal, and the B signal have the same photoelectric conversion characteristics. Is done. Details of the AE / WB evaluation value detection circuit 7 and the WB control circuit 8 will be described later.

  The R, G, and B signals that have been subjected to white balance processing by the WB control circuit 8 are subjected to color interpolation processing by the color interpolation circuit 9. When a color filter having a Bayer-type arrangement using RGB as shown in FIG. 2 is provided in the solid-state imaging device 2, the color signal output from each pixel is only the color signal from the color filter provided with the pixel. Therefore, the color interpolation circuit 9 performs color interpolation processing by generating other color signals from the color signals of adjacent pixels.

  When the RGB color filters are arranged in the pixels G11 to G44 as shown in FIG. 2, the R signals r11, r31, r13, and r33 are converted from the pixels G11, G31, G13, and G33 to the pixels G21, G41, and G33, respectively. G12, G32, G23, G43, G14, G34 to G signals g21, g41, g12, g32, g23, g43, g14, g34, and pixels G22, G42, G24, G44 to B signals b22, b42, b24, b44 Is output. At this time, RGB signals of the pixels G22, G23, G32, and G33 are expressed by the following equations.

R signal r22, G signal g22, B signal b22 of pixel G22
r22 = (r11 + r31 + r13 + r33) / 4
g22 = (g21 + g12 + g32 + g23) / 4
b22 = b22
R signal r32, G signal g32, B signal b32 of the pixel G32
r32 = (r31 + r33) / 2
g32 = g32
b32 = (b22 + b42) / 2
R signal r23, G signal g23, B signal b23 of pixel G23
r23 = (r13 + r33) / 2
g23 = g23
b23 = (b22 + b24) / 2
R signal r33, G signal g33, B signal b33 of pixel G33
r33 = r33
g33 = (g32 + g23 + g43 + g34) / 4
b33 = (b22 + b42 + b24 + b44) / 4.

When the RGB signal is obtained for each pixel by performing the color interpolation processing in this way, the RGB signal of each pixel is given to the color correction circuit 10 and the color correction processing for emphasizing the hue of each pixel is performed. Is done. At this time, each of the RGB signals is subjected to color correction by the values of other color signals. That is, by substituting the RGB signals rkl, gkl, bkl of the pixel Gkl into the following expression, the RGB signals rxkl, gxkl, bxkl of the pixel Gkl subjected to the hue correction are generated. At this time, the matrix coefficient is switched based on the dynamic range control signal input from the overall control unit 13, and the color tone of the RGB signal of each pixel is emphasized.
rxkl = a1 * rkl + a2 * gkl + a3 * bkl
gxkl = b1 * rkl + b2 * gkl + b3 * bkl
bxkl = c1 * rkl + c2 * gkl + c3 * bkl.

  The RGB signal subjected to the color correction by the color correction circuit 10 is given to the gradation conversion circuit 11 so that the dynamic range control signal and the AE evaluation value are input from the overall control unit 13 so as to obtain an appropriate output level. Based on the above, the gradation characteristics are changed by a change based on the γ curve or a change in digital gain. Then, as shown in FIG. 3, with respect to the edge component, the noise component superimposed on each of the RGB signals in the coring circuit 12 having level conversion characteristics for converting all outputs within a predetermined range to the reference signal level as seen from the reference signal level. Are removed, and edge components are extracted and subjected to edge enhancement processing.

<Configuration example of solid-state imaging device>
The configuration of the solid-state imaging device 2 in the imaging apparatus configured as shown in FIG. 1 will be described with reference to the drawings. FIG. 4 is a block diagram schematically showing a part of the configuration of the solid-state imaging device of this example, and FIG. 5 is a circuit diagram showing the configuration of each pixel.

  As shown in FIG. 4, in the solid-state imaging device 2, G11 to Gmn represent pixels arranged in a matrix (matrix arrangement). Reference numeral 21 denotes a vertical scanning circuit, which sequentially scans rows (lines) 23-1, 23-2,..., 23-n that apply a signal φV to each pixel and lines 24-1 and 24-2. ,..., 24-n, and a signal φVD is applied to each pixel via lines 25-1, 25-2,. A horizontal scanning circuit 22 sequentially reads out photoelectric conversion signals derived from the pixels to the output signal lines 26-1, 26-2, ..., 26-m in the horizontal direction for each pixel. Reference numeral 20 denotes a power supply line. For each pixel, not only the lines 23-1 to 23-n, 24-1 to 24-n, 25-1 to 25-n, the output signal lines 26-1 to 26-m, and the power supply line 20, but also These lines (for example, a clock line and a bias supply line) are also connected, but these are omitted in FIG.

  Also, constant current sources 27-1 to 27-m are connected to the output signal lines 26-1 to 26-m, and pixels are provided via the signal lines 26-1 to 26-m, respectively. Selection circuits 28-1 to 28-m for sample-holding image signals and noise signals supplied from G11 to Gmn are provided. Then, when the image signal and the noise signal are sequentially transmitted from the selection circuits 28-1 to 28-m to the correction circuit 29, the correction circuit 29 performs correction processing and outputs the image signal from which noise has been removed to the outside. Is done. The DC voltage VPS is applied to one end of the constant current sources 27-1 to 27-m.

  In such a solid-state imaging device, an image signal and a noise signal output from the pixel Gab (a natural number of a: 1 ≦ a ≦ m, b: 1 ≦ b ≦ n) are respectively output signal lines 26- The signal is output via a and amplified by a constant current source 27-a connected to the output signal line 26-a. The image signal and noise signal output from the pixel Gab are sequentially sent to the selection circuit 28-a, and the sent image signal and noise signal are sampled and held in the selection circuit 28-a. Thereafter, after the sampled and held image signal is sent to the correction circuit 29 from the selection circuit 28-a, the same sampled and held noise signal is sent to the correction circuit 29. The correction circuit 29 corrects the image signal given from the selection circuit 28-a based on the noise signal similarly given from the selection circuit 28-a, and outputs the noise-removed image signal to the amplifier 3.

  In the solid-state imaging device 2 having such a configuration, as shown in FIG. 5, the pixels G11 to Gmn have the drain of the MOS transistor T1 connected to the anode of the photodiode PD to which the DC voltage VPD is applied to the cathode. The gate and drain of the MOS transistor T2 and the gate of the MOS transistor T3 are connected to the source of T1. The gate of the MOS transistor T4 and the drain of the MOS transistor T5 are connected to the source of the MOS transistor T3, and the drain of the MOS transistor T6 is connected to the source of the MOS transistor T4. The source of the MOS transistor T6 is connected to the output signal line 26 (corresponding to the output signal lines 26-1 to 26-m in FIG. 4). The MOS transistors T1 to T6 are P-channel MOS transistors.

  The signal φVPS is input to the source of the MOS transistor T2 via the line 25 (corresponding to the lines 25-1 to 25-n in FIG. 4), and the DC voltage VPD is applied to the drains of the MOS transistors T3 and T4. Further, the other end of the capacitor C to which the signal φVD is applied via the line 24 (corresponding to the lines 24-1 to 24-n in FIG. 4) is connected to the source of the MOS transistor T3. The DC voltage VRG is input to the source of the MOS transistor T5, and the signal φRS is input to the gate thereof. Further, signals φS and φV are input to the gates of the MOS transistors T1 and T6, respectively.

  The signal φVPS is a binary voltage signal. When the amount of incident light exceeds a predetermined value, the voltage for operating the MOS transistor T2 in the subthreshold region is VL, and the voltage higher than this voltage is used for the MOS transistor T2. The voltage for making the conductive state is VH. The signal φVD is a ternary voltage signal, the voltage value when integrating the capacitor C is set to the highest Vh, the voltage value when reading the image signal is set to Vm lower than Vh, and the noise signal is read The voltage value is set to Vl lower than Vm.

  The operation of the pixels G11 to Gmn in the solid-state imaging device 2 configured as described above will be described with reference to the time chart of FIG. First, when a pulse signal φVD having a voltage value Vm and a pulse signal φV are supplied and an image signal is output, the signal φVD is set to Vh, then the signal φS is set high to turn off the MOS transistor T1, and the reset operation is performed. Begins. Next, the signal φVPS applied to the source of the MOS transistor T2 is set to VH, and the source voltage of the MOS transistor T2 is increased, so that the negative charge accumulated in the gate and drain of the MOS transistor T2 and the gate of the MOS transistor T3. Are quickly recombined. At this time, the signal φRS is set to low, the MOS transistor T5 is turned on, and the voltage at the connection node between the capacitor C and the gate of the MOS transistor T4 is initialized.

  Then, the signal φVPS applied to the source of the MOS transistor T2 is set to VL to return the potential state of the MOS transistor T2 to the original state, and then the signal φRS is set to high to turn off the MOS transistor T5. Thereafter, the capacitor C performs an integration operation, and the voltage at the connection node between the capacitor C and the gate of the MOS transistor T4 becomes in accordance with the reset gate voltage of the MOS transistor T2. Then, the pulse signal φV is applied to the gate of the MOS transistor T6 to turn on the MOS transistor T6 and set the voltage value of the signal φVD to Vl. At this time, since the MOS transistor T4 operates as a source follower type MOS transistor, a noise signal appears on the output signal line 26 as a voltage signal. Thereafter, the pulse signal φRS is again applied to the MOS transistor T5 to reset the voltage at the connection node between the capacitor C and the gate of the MOS transistor T4, and then the signal φS is set low to turn on the MOS transistor T1 to perform the imaging operation. Make it ready.

  After the noise signal is output in this way, the imaging operation is started when the MOS transistor T1 is turned on. At this time, the signal φRS is set high and the MOS transistor T5 is turned off. Further, the signal φVPS applied to the source of the MOS transistor T2 is set to VL, and the voltage value of the signal φVD applied to the capacitor C is set to Vh to perform the integration operation. When photocharge corresponding to the amount of incident light flows from the photodiode PD into the MOS transistor T2, the MOS transistor T2 is in a cut-off state, so that the photocharge is accumulated at the gate of the MOS transistor T2.

  Therefore, when the brightness of the subject to be imaged is low and the amount of incident light entering the photodiode PD is small, a voltage corresponding to the amount of photocharge accumulated at the gate of the MOS transistor T2 appears at the gate of the MOS transistor T2, A voltage that changes linearly with respect to the integrated value of the amount of light appears at the gate of the MOS transistor T3. Also, when the luminance of the subject to be imaged is high and the amount of incident light entering the photodiode PD is large, and the voltage according to the amount of photocharge accumulated at the gate of the MOS transistor T2 increases, the MOS transistor T2 operates in the subthreshold region. Therefore, a voltage that changes logarithmically with respect to the amount of incident light appears at the gate of the MOS transistor T3.

  Since a drain current that is linearly or naturally logarithmically changed with respect to the incident light amount flows from the capacitor C, the gate voltage of the MOS transistor T4 is set to the integrated value of the incident light amount. Thus, the voltage changes linearly or in a natural logarithm. Then, by setting the voltage value of the signal φVD to Vm and applying the pulse signal φV to the MOS transistor T6, a source current corresponding to the gate voltage of the MOS transistor T4 flows to the output signal line 6 via the MOS transistor T6. . At this time, since the MOS transistor T4 operates as a source follower type MOS transistor, an image signal appears as a voltage signal on the output signal line 6. Thereafter, the signal φV is set high to turn off the MOS transistor T6, and the voltage value of the signal φVD is set to Vh.

  When operating in this way, the voltage value VL of the signal φVPS at the time of imaging decreases, and the potential difference between the gate and the source of the MOS transistor T2 increases as the difference from the voltage value VH of the signal φVPS at the time of reset increases. The ratio of subject luminance at which the MOS transistor T2 operates in the cutoff state increases. Therefore, as shown in FIG. 7, the lower the voltage value VL, the larger the ratio of subject luminance to be linearly converted. Therefore, for example, the luminance range of the subject is detected, and if the luminance range of the subject is narrow, the voltage value VL is lowered to widen the luminance range for linear conversion, and if the luminance range of the subject is wide, the voltage value VL is increased. By widening the luminance range for logarithmic conversion, photoelectric conversion characteristics that match the characteristics of the subject can be obtained. It should be noted that when the voltage value VL is minimized, it is possible to always perform linear conversion. When the voltage value VL is maximized, it is possible to always perform logarithmic conversion.

  The solid-state image pickup device in which the dynamic range can be switched according to the luminance range of the subject by the overall control unit 13 switching the voltage value VL of the signal φVPS given to the pixels G11 to Gmn of the solid-state image pickup device 2 operating in this way. 2 can be used. That is, the inflection point (luminance value) for switching from the linear conversion operation to the logarithmic conversion operation in the pixels G11 to Gmn of the solid-state imaging device 2 can be set by switching the voltage value VL of the signal φVPS. it can. Note that the amount of photoelectric charge flowing into the MOS transistor T2 until reaching the gate voltage of the MOS transistor T2 when changing to the logarithmic conversion operation at the time of imaging is the same in all the pixels.

  In this configuration example, a solid-state imaging device including pixels configured as shown in FIG. 5 is used. However, the present invention is not limited to this configuration, and linear conversion operation and logarithmic conversion operation are automatically performed in each pixel. As long as it can be switched to the above, it may be composed of pixels having other configurations such as a pixel having a configuration as shown in Patent Document 2. In addition, the inflection point between the linear conversion operation and the logarithmic conversion operation is changed by changing the voltage value VL of the signal φVPS at the time of imaging. However, the linear value can be changed by changing the voltage value VH of the signal φVPS at the time of resetting. The inflection point between the conversion operation and the logarithmic conversion operation may be changed. The inflection point may be changed by changing the reset time. Further, although each pixel is provided with an RGB filter, other color filters such as cyan, magenta, and yellow may be provided.

<First Example of AE / WB Evaluation Value Detection Circuit>
A first example of the AE / WB evaluation value detection circuit in the imaging apparatus configured as shown in FIG. 1 will be described in detail below with reference to the drawings. FIG. 8 is a block diagram showing the internal configuration of the AE / WB evaluation value detection circuit of this example.

  As shown in FIG. 8, the AE / WB evaluation value detection circuit 7 of this example is provided with each of the RGB signals from which the FPN component has been removed by the FPN correction circuit 6 and is subjected to either linear conversion or logarithmic conversion. Photoelectric conversion characteristic discriminating units 71r, 71g, 71b for confirming whether or not, and average value calculation units 72r, 72g for obtaining average values r1av, g1av, b1av of the RGB signals subjected to linear conversion (with linear conversion characteristics) , 72b, and average value calculation units 73r, 73g, 73b for obtaining the average values r2av, g2av, b2av of the logarithmically converted RGB signals (having logarithmic conversion characteristics), and average value calculation units 72r, 72g, respectively. A WB evaluation value calculation unit 74r for obtaining a WB evaluation value wr1 for the R signal from the average values r1av and g1av of the RG signals, and an average value calculation unit 72g , 72b, a WB evaluation value calculation unit 74b for obtaining a WB evaluation value wb1 for the B signal from the average values g1av, b1av of the GB signals respectively received from the respective GB signals, and average values of the RG signals supplied from the average value calculation units 73r, 73g, respectively. The WB evaluation value calculation unit 75r for obtaining the WB evaluation value wr2 for the R signal from r2av and g2av, and the WB evaluation value wb2 for the B signal from the average values g2av and b2av of the GB signals given from the average value calculation units 73g and 73b, respectively. The WB evaluation value wr for the R signal is generated by weighted addition of the WB evaluation value calculation unit 75b to be obtained and the WB evaluation values wr1 and wr2 from the WB evaluation value calculation units 74r and 75r, respectively, and output to the overall control unit 13. WB evaluations from the weighted addition unit 76r and the WB evaluation value calculation units 74b and 75b, respectively. And a weighted addition unit 76b outputs the total control unit 13 generates a WB evaluation value wb for the B signal by weighted addition value wb1, wb2.

  Further, as shown in FIG. 9, the overall control unit 13 adjusts the dynamic range of the solid-state imaging device 2 and controls the timing of the clock output from the timing generation circuit 15, and AE / WB evaluation. In other words, the microcomputer 132 controls the sensor driving unit 131 according to the AE evaluation value and the WB evaluation value detected by the value detection circuit 7 and generates data to be given to the WB control circuit 8, in other words, according to the dynamic range of the solid-state imaging device 2. For example, a memory 133 that stores data that provides photoelectric conversion characteristics according to the position of the switching point between the linear conversion characteristic and the logarithmic conversion characteristic. For example, the microcomputer 132 provides the sensor driving unit 131 with a dynamic range control signal for changing the dynamic range of the solid-state imaging device 2 so that an appropriate dynamic range can be obtained according to the luminance range of the subject. The sensor driving unit 131 changes the driving condition based on the dynamic range control signal, and changes the dynamic range of the solid-state imaging device 2.

The operation of the AE / WB evaluation value detection circuit 7 configured as shown in FIG. 8 will be described below with reference to the drawings. First, the RGB signal from which the FPN component has been removed by the FPN correction circuit 6 is given to each of the photoelectric conversion characteristic discriminating units 71r, 71g, 71b. A typical example of the RGB signal input in this way is shown in FIG. FIG. 10 is a graph showing the relationship of the signal level of the RGB signal with respect to the luminance value, and the luminance value is represented by a logarithmic value. That is, when the voltage VL of the signal φVPS supplied from the sensor driving unit 131 to the solid-state imaging device 2 is set by the dynamic range control signal from the microcomputer 132 of the overall control unit 13, the black reference correction circuit 5 and the FPN correction circuit 6 are set. In order to eliminate the offset, the potential positions at which the operation of the MOS transistor T2 of each pixel determined by the voltage VL of the signal φVPS is switched can be made substantially equal. Therefore, as shown in FIG. 10, in each of the RGB signals, the signal level that becomes an inflection point at which the linear conversion characteristic is switched to the logarithmic conversion characteristic becomes equal.

A signal level serving as an inflection point at which the linear conversion characteristic in the RGB signal is switched to the logarithmic conversion characteristic is defined as a threshold level Vth. When the voltage VL of the signal φVPS to be given to the solid-state imaging device 2 is set by the sensor driving unit 131 of the overall control unit 13, this threshold level Vth is obtained from the microcomputer 132 of the overall control unit 13 as dynamic range data. It is given to each of the photoelectric conversion characteristic discriminating units 71r, 71g, 71b. Therefore, the photoelectric conversion characteristic discriminating units 71r, 71g, 71b determine that the signal level is logarithmically converted if the signal level is higher than the threshold level Vth, and if the signal level is equal to or lower than the threshold level Vth, the signal is linearly converted. Judge that there is. The signal level may be determined to be a logarithmically converted signal when it is equal to or higher than the threshold level Vth, and may be determined to be a linearly converted signal when the signal level is lower than the threshold level Vth. The same applies to the following description.

  Then, the R signal determined by the photoelectric conversion characteristic determination unit 71r to be a signal linearly converted with the signal level equal to or lower than the threshold level Vth is given to the average value calculation unit 72r, and also in the photoelectric conversion characteristic determination unit 71r. The R signal determined to be a logarithmically converted signal having a signal level higher than the threshold level Vth is provided to the average value calculator 73r. Similarly, the G signal determined by the photoelectric conversion characteristic determination unit 71g to be a signal linearly converted with the signal level equal to or lower than the threshold level Vth is given to the average value calculation unit 72g, and the photoelectric conversion characteristic determination unit 71g. The G signal determined to be a logarithmically converted signal having a signal level higher than the threshold level Vth is provided to the average value calculation unit 73g. In addition, the B signal determined by the photoelectric conversion characteristic determination unit 71b as a signal linearly converted with the signal level equal to or lower than the threshold level Vth is given to the average value calculation unit 72b, and the photoelectric conversion characteristic determination unit 71b The B signal determined to be a logarithmically converted signal having a signal level higher than the threshold level Vth is provided to the average value calculation unit 73b.

  The average value calculators 72r, 72g, and 72b add the signal levels of the linearly converted RGB signals given from the photoelectric conversion characteristic discriminators 71r, 71g, and 71b, respectively, and each of the given RGB signals. Count the total number. Similarly, the average value calculation units 73r, 73g, and 73b add the respective signal levels of the logarithmically converted RGB signals provided from the photoelectric conversion characteristic determination units 71r, 71g, and 71b, respectively. Count the total number of In this way, when all the RGB signals are output from the photoelectric conversion characteristic determination units 71r, 71g, 71b, a signal indicating that all the RGB signals have been output is sent from the photoelectric conversion characteristic determination unit 71r to the average value calculation units 72r, 73r. The photoelectric conversion characteristic discriminating part 71g is sent to the average value calculating parts 72g and 73g, and the photoelectric conversion characteristic discriminating part 71b is sent to the average value calculating parts 72b and 73b, respectively.

  Thereafter, in each of the average value calculation units 72r, 72g, 72b, 73r, 73g, and 73b, the average value calculation is performed by dividing the summed signal level by the total number of given signals. In this way, the average value r1av of the linearly converted R signal is changed from the average value calculation unit 72r to the WB evaluation value calculation unit 74r, and the average value g1av of the linearly converted G signal is changed from the average value calculation unit 72g to WB. The average value b1av of the linearly converted B signal is sent from the average value calculation unit 72b to the WB evaluation value calculation unit 74b to the evaluation value calculation units 74r and 74b. Similarly, the average value r2av of the logarithmically converted R signal is converted from the average value calculator 73r to the WB evaluation value calculator 75r, and the average value g2av of the logarithmically converted G signal is converted from the average value calculator 73g to the WB evaluation value calculator. The average value b2av of the B signal logarithmically converted is sent to 75r and 75b from the average value calculation unit 73b to the WB evaluation value calculation unit 75b, respectively.

  Then, in the WB evaluation value calculation unit 74r to which the average values r1av and g1av of the linearly converted RG signal are given, photoelectric conversion of the average values r1av and g1av of the RG signal and the G signal given from the microcomputer 132 of the overall control unit 13 is performed. From the characteristics, the WB evaluation value wr1 for the linearly converted R signal is obtained, and the average value g1av of the GB signal is obtained in the WB evaluation value calculation unit 74b to which the average value g1av and b1av of the linearly converted GB signal is given. The WB evaluation value wb1 for the linearly converted B signal is obtained from b1av and the photoelectric conversion characteristics of the G signal given from the microcomputer 132 of the overall control unit 13.

  Similarly, in the WB evaluation value calculator 75r to which the logarithmically converted RG signal average values r2av and g2av are given, the RG signal average values r2av and g2av and the G signal photoelectricity given from the microcomputer 132 of the overall control unit 13 are used. From the conversion characteristics, the WB evaluation value wr2 for the logarithmically converted R signal is obtained, and the average value g2av of the GB signal is obtained in the WB evaluation value calculation unit 75b to which the average values g2av and b2av of the logarithmically converted GB signal are given. , B2av and the photoelectric conversion characteristic of the G signal given from the microcomputer 132 of the overall control unit 13, the WB evaluation value wb2 for the logarithmically converted B signal is obtained. The WB evaluation value calculators 74r, 74b, 75r, and 75b are each given a G signal photoelectric conversion characteristic according to the dynamic range of the solid-state imaging device 2 from the microcomputer 132 of the overall controller 13.

Processing operations in the WB evaluation value calculation units 74r, 74b, 75r, and 75b will be described by taking the WB evaluation value calculation units 74r and 75r as an example. It is assumed that the photoelectric conversion characteristics of the G signal as shown in FIG. 11 are given to the WB evaluation value calculation units 74r, 74b, 75r, and 75b from the microcomputer 132 of the overall control unit 13. At this time, the WB evaluation value calculation unit 74r first obtains the luminance value Lav in the average value g1av of the G signal based on the photoelectric conversion characteristics of the G signal as shown in FIG. That is, when the linear conversion characteristic region of the G signal is expressed by the equation (1), the luminance value Lav (= (g1av−C) is calculated by substituting the average value g1av of the G signal into the equation (1). ) / Ag).
V = Ag × L + C (1)
(V: signal level, L: luminance, Ag: photoelectric conversion coefficient for G signal, C: offset).

Then, assuming that the average value r1av of the R signal is obtained for this luminance value Lav, the photoelectric conversion coefficient Ar (= (r1av−C) / Lav) for the R signal is obtained, and FIG. Thus, the photoelectric conversion characteristic of the R signal in the linear conversion characteristic region is obtained. It should be noted that the expression representing the linear conversion characteristic region of the R signal is expressed as Expression (2), and the offset C is equal to Expression (1).
V = Ar × L + C (2).

  When the photoelectric conversion characteristic of the R signal in the linear conversion characteristic region is obtained in this way, the luminances Lrth and Lgth for the RG signals having the threshold level Vth are obtained from the photoelectric conversion characteristics of the RG signals as shown in FIG. It is done. That is, the luminance levels Lgth (= (Vth−C) / Ag) and Lrth (= (Vth−C) / Ar) are calculated by substituting the threshold level Vth into each of the expressions (1) and (2). Is required. The WB evaluation value wr1 for the linearly converted R signal is obtained as the difference value Lgth-Lrth based on the luminances Lrth and Lgth of the RG signals having the threshold level Vth thus obtained.

Further, in the WB evaluation value calculation unit 75r, first, as shown in FIG. 12A, the logarithm value ln (Lav) of the luminance value in the average value g2av of the G signal is obtained based on the photoelectric conversion characteristics of the G signal. That is, when the logarithmic conversion characteristic region of the G signal is expressed by the expression (3), the logarithmic value ln (Lav) of the luminance value is calculated by substituting the average value g2av of the G signal into the expression (3) and performing the reverse calculation. (= (G2av−βg) / α) can be obtained. Note that the photoelectric conversion characteristic of the G signal in FIG. 12 is equal to the photoelectric conversion characteristic of the G signal in FIG.
V = α × ln (L) + βg (3)
(Α: predetermined amplification factor, βg: logarithmic conversion value of photoelectric conversion coefficient for G signal).

Then, by assuming that the average value r2av of the R signal is obtained for the logarithmic value ln (Lav) of this luminance value, the logarithmic conversion value βr (= r2av−α × ln (Lav) of the photoelectric conversion coefficient for the R signal is obtained. ) = R2av−g2av + βg), and the photoelectric conversion characteristic of the R signal in the logarithmic conversion characteristic region is obtained as shown in FIG. The expression representing the logarithmic conversion characteristic region of the R signal is expressed as the following expression (4), and the amplification factor α is equal to the expression (3).
V = α × ln (L) + βr (4).

  When the photoelectric conversion characteristic of the R signal in the logarithmic conversion characteristic region is obtained in this way, the logarithmic values ln (Lrth) and ln (Lgth) of the luminance for each RG signal having the threshold level Vth are as shown in FIG. It is obtained from the photoelectric conversion characteristics of each RG signal. That is, by substituting the threshold level Vth into each of the equations (3) and (4) and calculating backward, the luminance logarithm value ln (Lgth) (= (Vth−βg) / α), ln (Lrth) ( = (Vth−βr) / α). Therefore, the luminance Lrth (= exp ((Vth−βr) / α)) and Lgth (= exp ((Vth−βg) / α)) for each RG signal having the threshold level Vth is finally obtained. The WB evaluation value wr2 for the logarithmically converted R signal is obtained as the difference value Lgth-Lrth based on the luminances Lrth and Lgth of the RG signals having the threshold level Vth thus obtained.

When the WB evaluation values wr1, wb1, wr2, and wb2 are output by performing such processing operations in the WB evaluation value calculation units 74r, 74b, 75r, and 75b, the WB evaluation values wr1 and wr2 are weighted and added. The WB evaluation values wb1 and wb2 are given to the weighted addition unit 76b. A weighting coefficient corresponding to the set dynamic range of the solid-state imaging device 2 is given to each of the weighted addition units 76r and 76b from the microcomputer 132 of the overall control unit 13. Therefore, when weighting coefficients xr, yr for the WB evaluation values wr1, wr2 are given in the weighted addition unit 76r, the WB evaluation value wr is obtained as shown in equation (5). In addition, when weighting factors xb and yb for the WB evaluation values wb1 and wb2 are given in the weighted addition unit 76b, the WB evaluation value wb is obtained as shown in equation (6).
wr = xr * wr1 + yr * wr2 (5)
wb = xb × wb1 + yb × wb2 (6).

  The WB evaluation values wb and wr obtained in this way by the weighted addition units 76r and 76b are given to the microcomputer 132 of the overall control unit 13. The microcomputer 132 determines a set value to be given to the WB control unit 8 based on the WB evaluation values wb and wr and the dynamic range data. In this example, the weighting factors xr, yr, xb, and yb given to the weighted addition units 76r and 76b are set according to the set dynamic range of the solid-state imaging device 2. The microcomputer 132 may be set according to the distribution range or the luminance value and given to the weighted addition units 76r and 76b. Further, the weight coefficients xr, yr, xb, yb may be set from the outside.

<Second Example of AE / WB Evaluation Value Detection Circuit>
The AE / WB evaluation value detection circuit 7 in the imaging apparatus configured as shown in FIG. 1 will be described in detail below with reference to the drawings. FIG. 13 is a block diagram showing the internal configuration of the AE / WB evaluation value detection circuit of this example. In the AE / WB evaluation value detection circuit shown in FIG. 13, the detailed description of the parts used for the same purpose as the AE / WB evaluation value detection circuit of FIG. 8 is omitted, and the same reference numerals are given.

  As shown in FIG. 13, the AE / WB evaluation value detection circuit 7 of this example includes photoelectric conversion characteristic determination units 71r, 71g, 71b, average value calculation units 72r, 72g, 72b, 73r, 73g, 73b, and WB. The total number of each of the linearly converted signal and the logarithmically converted signal confirmed by the evaluation value calculating units 74r, 74b, 75r, and 75b, the weighted adding units 76r and 76b, and the photoelectric conversion characteristic discriminating units 71r, 71g, and 71b. And a weighting factor setting unit 77 that counts and sets the weighting factors xr, yr, xb, and yb based on these count values.

  When configured in this manner, the photoelectric conversion characteristic discriminating units 71r, 71g, 71b, the average value calculating units 72r, 72g, 72b, 73r, 73g, 73b, the WB evaluation value calculating units 74r, 74b, 75r, 75b, and The weighted addition units 76r and 76b perform the same operation as the AE / WB evaluation value detection circuit (FIG. 8) in the first example. That is, in the photoelectric conversion characteristic discriminating units 71r, 71g, 71b, the signal level of the input RGB signal is compared with the threshold level Vth, and it is a logarithmically converted signal or a linearly converted signal. Is determined. Then, RGB signals confirmed to be linearly converted by the photoelectric conversion characteristic discriminating units 71r, 71g, 71b are given to the average value calculating units 72r, 72g, 72b, and the average values r1av, g1av, b1av are given. The RGB signals obtained and confirmed to be logarithmically converted by the photoelectric conversion characteristic discriminating units 71r, 71g, 71b are given to the average value calculating units 73r, 73g, 73b, and the average values r2av, g2av , B2av.

  Thereafter, the WB evaluation value calculation unit 74r obtains the WB evaluation value wr1 for the linearly converted R signal based on the average values r1av and g1av and the photoelectric conversion characteristics of the G signal, and the WB evaluation value calculation unit 75r Based on the average values r2av, g2av and the photoelectric conversion characteristics of the G signal, a WB evaluation value wr2 for the logarithmically converted R signal is obtained. Further, in the WB evaluation value calculation unit 74b, the WB evaluation value wb1 for the linearly converted B signal is obtained based on the average values g1av, b1av and the photoelectric conversion characteristics of the G signal, and in the WB evaluation value calculation unit 75b, Based on the average values g2av, b2av and the photoelectric conversion characteristics of the G signal, a WB evaluation value wb2 for the logarithmically converted B signal is obtained. Then, the weighted addition unit 76r performs weighted addition of the WB evaluation values wr1 and wr2 using the weighting factors xr and yr given from the weighting factor setting unit 77, thereby obtaining the WB evaluation value wr and performing the weighted addition. The unit 76b performs weighted addition of the WB evaluation values wb1 and wb2 using the weighting factors xb and yb given from the weighting factor setting unit 77, thereby obtaining the WB evaluation value wb.

  Thus, when obtaining the WB evaluation values wr and wb, unlike the first example, the weighting factor setting unit 77 sets weighting factors xr, yr, xb and yb to be given to the weighting addition units 76r and 76b. Therefore, hereinafter, the operation of the weighting coefficient setting unit 77 will be described. First, when the discrimination results for the RGB signals are given to the weighting coefficient setting unit 77 by the photoelectric conversion characteristic discriminating units 71r, 71g, 71b, the total number or logarithmically converted signals are linearly converted according to the given discrimination result. Count the total number of signals. Therefore, the total number of R signals transmitted from the photoelectric conversion characteristic determination unit 71r to the average value calculation units 72r and 73r is n1r and n2r, respectively, and is output from the photoelectric conversion characteristic determination unit 71g to the average value calculation units 72g and 73g, respectively. When the total number of G signals is n1g and n2g, and the total number of B signals sent from the photoelectric conversion characteristic determination unit 71b to the average value calculation units 72b and 73b is n1b and n2b, the total number of linearly converted signals Is n1 (= n1r + n1g + n1b), and the total number of logarithmically converted signals is n2 (= n2r + n2g + n2b).

  Then, the weighting coefficients xr, yr, xb, yb are set according to the ratio of the total number n1 of linearly converted signals and the total number n2 of logarithmically converted signals. At this time, for example, xr = xb = n1 / (n1 + n2) and yr = yb = n2 / (n1 + n2) are set so that the weighting coefficient for a signal whose total number increases is increased. When the weighting coefficients xr, yr, xb, yb are set in this way, the weighting coefficients xr, yr are given to the weighted addition unit 76r, and the weighting coefficients xb, yb are given to the weighted addition unit 76b.

  In the AE / WB evaluation value setting unit 7 of this example, the weighting coefficient setting unit 77 uses the total number n1 of linearly converted signals and the total number n2 of logarithmically converted signals for all RGB signals. The weighting coefficients xr, yr, xb, and yb are obtained, but the total number n1r, n1g, and n1b of the linearly converted signals for each of the RGB signals and the total number n2r, n2g, and n2b of the logarithmically converted signals. And the weighting coefficients xr, yr, xb, and yb may be obtained. At this time, the weighting coefficients xr and yr are obtained from the relationship between the total number n1r of the R signals subjected to linear transformation and the total number n2r of the logarithmically transformed R signals, and the weighting factors xb and yb are obtained from the linearly transformed B signal. May be obtained from the relationship between the total number n1b of the B signals and the total number n2b of the logarithmically converted B signals. Further, the weighting coefficients xr and yr are obtained from the relationship between the total number n1r and n1g of each of the linearly converted RG signals and the total number n2r and n2g of the logarithmically converted RG signals, and the weighting coefficients xb and yb are linearly converted. The total number n1g and n1b of the GB signals thus obtained and the total number n2g and n2b of the logarithmically converted GB signals may be obtained.

  In addition, when an autofocus (AF) function for detecting the main subject is provided, the pixels in the region centered on the main subject detected by the AF function are logarithmically converted with the number of pixels that output a linearly converted signal. The weighting coefficient may be set according to the relationship with the number of pixels that output a signal.

  In the AE / WB evaluation value setting unit 7 of the first and second examples described above, the photoelectric conversion characteristics of the G signal are given to the WB evaluation value calculation units 74r, 74b, 75r, and 75b, and the WB evaluation value wr1. , Wb1, wr2, and wb2 are obtained, the luminance value L1av in the average value of the linearly converted signal is given to the WB evaluation value calculation units 74r and 74b, and the luminance in the average value of the logarithmically converted signal The value L2av may be given to the WB evaluation value calculators 75r and 75b to obtain the WB evaluation values wr1, wb1, wr2, and wb2.

  At this time, the WB evaluation value calculation unit 74r confirms the photoelectric conversion characteristics of each of the RG signals based on the relationship between the average values r1av and g1av of each of the linearly converted RG signals and the luminance value L1av, and the threshold level of each of the RG signals. A WB evaluation value wr1 that is a difference in luminance value corresponding to Vth is obtained. Similarly, the WB evaluation value calculation unit 75r confirms the photoelectric conversion characteristics of each RG signal from the relationship between the average values r2av and g2av of each logarithmically converted RG signal and the luminance value L2av, and obtains the WB evaluation value wr2. . Similarly, the WB evaluation value calculation unit 74b confirms the photoelectric conversion characteristics of each GB signal from the relationship between the average values g1av and b1av and the luminance value L1av of each linearly converted GB signal, and obtains the WB evaluation value wb1. In addition, the WB evaluation value calculation unit 75b confirms the photoelectric conversion characteristics of each GB signal from the relationship between the average values g2av and b2av of each logarithmically converted GB signal and the luminance value L2av, and obtains the WB evaluation value wb2. .

<First Example of Data Table Generation Operation by Overall Control Unit>
Below, the 1st example of the data table production | generation operation | movement by the whole control part is demonstrated. When the AE / WB evaluation value setting unit 7 operates as in the first example or the second example of the AE / WB evaluation value setting unit and the WB evaluation values wr and wb are set in the AE / WB evaluation value setting unit 7, the configuration shown in FIG. This is given to the microcomputer 132 of the overall control unit 13. When the microcomputer 132 confirms the WB evaluation values wr and wb, the photoelectric conversion characteristic for each of the RGB signals is obtained from the memory 133 based on the WB evaluation values wr and wb and the size of the dynamic range set for the solid-state imaging device 2. read out. Then, the microcomputer 132 generates a data table for performing white balance processing, and supplies the data table to the WB control circuit 8.

  At this time, the photoelectric conversion characteristics of the G signal are discretely stored in the memory 133 according to the dynamic range of the solid-state imaging device 2, for example, as shown in the graph of FIG. The photoelectric conversion characteristics are stored discretely as shown in the graph of FIG. 14 according to the WB evaluation value for each dynamic range. Further, as shown in the graph of FIG. 7, four types of photoelectric conversion characteristics a1 to a4 are stored as G signal photoelectric conversion characteristics, and as shown in the graph of FIG. 14, RB signal photoelectric conversion characteristics are 6 for each dynamic range. When the types of photoelectric conversion characteristics b1 to b6 are stored, 4 × 6 types of photoelectric conversion characteristics are stored in the memory 133.

At this time, the parameters A and C in the equation (7) representing the linear conversion characteristic region of the photoelectric conversion property and the parameters α and β in the equation (8) representing the logarithmic conversion property region of the photoelectric conversion property are stored in the memory 133. 28 types are stored. FIG. 14 is based on the photoelectric conversion characteristics of the G signal when the dynamic range corresponding to the photoelectric conversion characteristics a2 in FIG. 7 is selected.
V = A × L + C (7)
V = α × ln (L) + β (8).

  Then, when the solid-state imaging device 2 is set to have a predetermined dynamic range, the photoelectric conversion characteristic of the G signal corresponding to the selected dynamic range is read from the memory 133. Further, when the WB evaluation values wr and wb are given from the AE / WB evaluation value detection circuit 7, the selected dynamic range, the photoelectric conversion characteristic of the R signal according to the WB evaluation value wr, the selected dynamic range, The photoelectric conversion characteristics of the B signal corresponding to the WB evaluation value wb are read from the memory 133. That is, when the sensor driving unit 131 drives and controls the solid-state imaging device 2 so that the dynamic range according to the photoelectric conversion characteristic a2 in FIG. 7 is obtained, first, the photoelectric conversion characteristic a2 is obtained as the G signal photoelectric conversion characteristic from the memory 133. Read out. When a WB evaluation value wr that is ΔL1 and a WB evaluation value wb that is −ΔL2 are given, the photoelectric conversion characteristic b4 is the photoelectric conversion characteristic of the R signal, and the photoelectric conversion characteristic b2 is the photoelectric conversion characteristic of the B signal. Are read from the memory 133.

  As described above, when the photoelectric conversion characteristics of the RGB signals are read from the memory 133, the microcomputer 132 generates data tables Dr and Db for the RB signals to be given to the WB control circuit 8 using these photoelectric conversion characteristics. The operation of the microcomputer 132 will be described with reference to the drawings. FIG. 15 shows the flow of data table generation for each RB signal in the microcomputer 132 in the form of a functional block diagram. Now, it is assumed that the signal levels of the RGB signals are each represented by 10 bits (0 to 1023).

  In the microcomputer 132, first, in the luminance calculation block 134r, the luminance value of each of the signal levels 0 to 1023 of the R signal is obtained based on the photoelectric conversion characteristics of the R signal read out by the memory 133. Similarly, in the luminance calculation block 134b, the luminance values of the signal levels 0 to 1023 of the B signal are obtained based on the photoelectric conversion characteristics of the B signal read out by the memory 133. That is, for the R signal, the luminance value of each signal level is obtained based on the photoelectric conversion characteristic b4, and for the B signal, the luminance value of each signal level is obtained based on the photoelectric conversion characteristic b2. Therefore, for each RB signal, for example, luminance values Lrx and Lbx with respect to the signal level Vx are obtained by using the photoelectric conversion characteristics b4 and b2 as shown in FIG.

  The luminance values obtained by the luminance calculation blocks 134r and 134b are given to the signal value calculation blocks 135r and 135b. Then, in the signal value calculation block 135r, based on the photoelectric conversion characteristics of the G signal read out by the memory 133, the signal level after the correction processing for each luminance value of the signal level 0 to 1023 of the R signal is obtained. Similarly, in the signal value calculation block 135b, based on the photoelectric conversion characteristics of the G signal read out by the memory 133, the signal level after the correction processing for each luminance value of the signal level 0 to 1023 of the B signal is obtained. That is, based on the photoelectric conversion characteristic a2, the signal level for the luminance value obtained for each signal level is obtained. Therefore, for each RB signal, as shown in FIG. 16B, the photoelectric conversion characteristic a2 is used. For example, from the luminance values Lrx and Lbx for the signal level Vx, the signal level Vrx after the correction processing for the signal level Vx. , Vbx.

  In this way, when the signal level after correction processing is obtained for each of the signal levels 0 to 1023 of each RB signal, the signal level after correction processing of each RB signal is obtained from the signal value calculation blocks 135r and 135b. Is provided to the database generation blocks 136r and 136b. In this database generation block 136r, signal levels 0 to 1023 of the R signal are used as input addresses. Then, a database Dr is generated that stores the 1024 corrected signal levels finally obtained by the signal value calculation block 135r for each of the signal levels 0 to 1023 in correspondence with the input addresses 0 to 1023. . Similarly, in the database generation block 136b, signal levels 0 to 1023 of the B signal are used as input addresses. Then, a database Db is generated that stores the 1024 corrected signal levels finally obtained by the signal value calculation block 135b for each of the signal levels 0 to 1023 in correspondence with the input addresses 0 to 1023. . The databases Dr and Db generated in this way are sent to the WB control circuit 8.

  In the above description, the photoelectric conversion characteristics of each of the RGB signals are stored in the memory 133, but only the photoelectric conversion characteristics of the G signal are stored in the memory 133, and the photoelectric conversion characteristics of the RB signal are the above-described WB evaluation value wr. , Wb may be obtained by calculation. For example, the parameter A (Ar) in the equation (7) representing the linear characteristic region of the photoelectric conversion property with respect to the R signal can be calculated from the following equations (9) to (11).

Vth = Ag × Lg + C (9)
Vth = Ar × (Lg + wr) + C (10)
From the formulas (9) and (10) Ar = (Ag × Lg) / (Lg + wr) (11)
However, Ag shows the photoelectric conversion coefficient with respect to G signal, Lg shows the brightness | luminance of G signal.

  Similarly, the logarithmic characteristic region of the R signal can be obtained by calculation. Further, the photoelectric conversion characteristic regarding the B signal can be obtained by calculation similarly to the R signal. As described above, when the photoelectric conversion characteristics are obtained by calculation, high-accuracy white balance processing can be performed.

<Second Example of Data Table Generation Operation by Overall Control Unit>
Next, a second example of the data table generation operation by the overall control unit will be described. In this example, for the same part as the first example of the data table generation operation described above, the first example of the data table generation operation is referred to, and detailed description thereof is omitted. In this example, unlike the first example, only the G signal photoelectric conversion characteristics corresponding to the dynamic range of the solid-state imaging device 2 are stored in the memory 133, and the photoelectric conversion characteristics of each RB signal are as follows: It is generated based on the photoelectric conversion characteristics read out by the memory 133.

  The data table generation operation in this example will be described below with reference to FIG. FIG. 17 shows the flow of data table generation operation for each RB signal in the microcomputer 132 in the form of a functional block diagram. Now, it is assumed that the signal levels of the RGB signals are each represented by 10 bits (0 to 1023). In the microcomputer 132, first, the photoelectric conversion characteristic of the G signal read from the memory 133 and the WB evaluation value wr from the AE / WB evaluation value detection circuit 7 are given to the photoelectric conversion characteristic generation block 137r, and the photoelectric conversion characteristic of the R signal is Generated. Similarly, the photoelectric conversion characteristic of the G signal and the WB evaluation value wb are given to the photoelectric conversion characteristic generation block 137b, and the photoelectric conversion characteristic of the B signal is generated.

  That is, when the photoelectric conversion characteristics of the G signal are read out from the memory 133, the photoelectric conversion characteristic generation blocks 137r and 137b respectively perform the following equation (7) for each RB signal based on the WB evaluation values wr and wb. A and β in Equation A and Equation (8) are obtained, and photoelectric conversion characteristics of each RB signal are generated. Therefore, for example, when the dynamic range of the solid-state imaging device 2 is set, the photoelectric conversion characteristic a2 in FIG. 7 is read as the G signal photoelectric conversion characteristic, and the WB evaluation values wr and wb are ΔLr and ΔLb, respectively. As shown in FIG. 18, the photoelectric conversion characteristic of the R signal becomes the photoelectric conversion characteristic br, and the photoelectric conversion characteristic of the B signal becomes the photoelectric conversion characteristic bb.

  The photoelectric conversion characteristics of the RB signals generated in the photoelectric conversion characteristic generation blocks 137r and 137b are given to the luminance calculation blocks 134r and 134b. Therefore, when the photoelectric conversion characteristic of each RB signal is set as shown in FIG. 18, the luminance calculation block 134r obtains the luminance value for each of the signal levels 0 to 1023 of the R signal based on the photoelectric conversion characteristic br. In the luminance calculation block 134b, the luminance value for each of the signal levels 0 to 1023 of the B signal is obtained based on the photoelectric conversion characteristic bb. Thereafter, in the signal value calculation blocks 135r and 135b, the signal level after the correction processing is obtained based on the luminance values obtained in the luminance calculation blocks 134r and 134b, respectively. In the database generation blocks 136r and 136b, the RB signals are obtained. Databases Dr and Db are generated.

  Therefore, the database Dr uses the signal level 0 to 1023 of the R signal as an input address, and the signal level after correction processing for the signal level 0 to 1023 obtained by the signal value calculation block 135r corresponds to each input address. Stored. Further, the database Db uses the signal level 0 to 1023 of the B signal as an input address, and the signal level after correction processing for the signal level 0 to 1023 obtained by the signal value calculation block 135b corresponds to each input address. Stored. The luminance calculation blocks 134r and 134b, the signal value calculation blocks 135r and 135b, and the database generation blocks 136r and 136b perform the same operation as in the first example.

<Third example of data table generation operation by overall control unit>
Next, a third example of the data table generation operation by the overall control unit will be described. In this example, for the same part as the second example of the data table generation operation described above, the second example of the data table generation operation is referred to, and the detailed description thereof is omitted. In this example, unlike the second example, after the luminance value corresponding to the signal level of the RB signal is obtained, AE gain adjustment and gradation conversion are performed.

  The data table generation operation in this example will be described below with reference to FIG. FIG. 19 shows the flow of data table generation for each RB signal in the microcomputer 132 in the form of a functional block diagram. Now, it is assumed that the signal levels of the RGB signals are each represented by 10 bits (0 to 1023). In the microcomputer 132, first, similarly to the second example, in each of the photoelectric conversion characteristic generation blocks 137r and 137b, the photoelectric conversion characteristic of the G signal read from the memory 133 and the WB evaluation value wr, Based on wb, photoelectric conversion characteristics of each RB signal are generated.

  Then, the photoelectric conversion characteristics of the RB signals generated in the photoelectric conversion characteristic generation blocks 137r and 137b are given to the luminance calculation blocks 134r and 134b, the luminance values for the signal levels 0 to 1023 of the R signal, and the B signal The luminance value for each of the signal levels 0 to 1023 is obtained. In the luminance calculation block 134g, the luminance value for each of the signal levels 0 to 1023 of the G signal is obtained based on the photoelectric conversion characteristics of the G signal read from the memory 133. In this way, the luminance value of each signal level in each of the RGB signals is given to the AE gain adjustment blocks 138r, 138g, and 138b.

  The AE gain adjustment blocks 138r, 138g, and 138b amplify or reduce each luminance value based on the AE evaluation value given from the AE / WB evaluation value detection circuit 7. This AE gain adjustment is a process of changing the brightness by changing the gain of the luminance value and performing gain adjustment to brighten or darken the imaged subject. That is, in the AE gain adjustment block 138r, the luminance value for each of the signal levels 0 to 1023 of the R signal is amplified or reduced by the amplification factor based on the AE evaluation value, and the signal level 0 to 1023 of the G signal in the AE gain adjustment block 138g. The luminance value for each is amplified or reduced by the amplification factor based on the AE evaluation value, and the luminance value for each of the signal levels 0 to 1023 of the B signal is amplified or reduced by the amplification factor based on the AE evaluation value in the AE gain adjustment block 138b. .

  The luminance values corresponding to the signal levels 0 to 1023 of the RGB signals subjected to gain adjustment in this way are given to the gradation conversion blocks 139r, 139g, and 139b. In the gradation conversion blocks 139r, 139g, and 139b, the AE gain adjustment is performed to give each luminance value of the RGB signal a characteristic for obtaining a target luminance when reproduced and displayed on a reproduction output device such as a monitor. The luminance value given from each of the blocks 138r, 138g, and 138b is subjected to gradation conversion by gradation characteristics in the reproduction output device. That is, when the reproduction output device is a CRT monitor, the characteristic by the γ curve becomes the gradation characteristic, and therefore, in the gradation conversion block 139r, the luminance value for each of the signal levels 0 to 1023 of the R signal subjected to gain adjustment. In the gradation conversion block 139g, the luminance value for each of the signal levels 0 to 1023 of the G signal subjected to gain adjustment is subjected to γ correction, and in the gradation conversion block 139b, Γ correction is performed on the luminance value for each of signal levels 0 to 1023 of the B signal subjected to gain adjustment.

  The luminance values corresponding to the signal levels 0 to 1023 of the RGB signals subjected to gain adjustment and gradation conversion in this way are given to the signal value calculation blocks 135r, 135g, and 135b. Thereafter, in the signal value calculation blocks 135r, 135g, and 135b, correction processing is performed based on the luminance values given from the gradation conversion blocks 139r, 139g, and 139b and the photoelectric conversion characteristics of the G signal read from the memory 133. The later signal level is determined. Thereafter, when the signal level after the correction processing is given to the database generation blocks 136r, 136g, and 136b, the databases Dr, Dg, and Db of the RGB signals are generated. The signal value calculation blocks 135r, 135g, 135b and the database generation blocks 136r, 136g, 136b perform the same operations as the signal value calculation blocks 135r, 135b and the database generation blocks 136r, 136b in the first and second examples. .

  Therefore, the database Dg generated as described above is a database that stores data obtained by performing gain adjustment and gradation conversion on the G signal, and the databases Dr and Db are respectively stored in the RB signal. On the other hand, it is a database that stores data on which white balance processing, gain adjustment, and gradation conversion have been performed. Accordingly, by performing the data table generation operation processing in this example, the WB control unit 8 can perform white balance processing, gain adjustment, and gradation conversion for each of the RGB signals. 1 can be omitted.

  In each example of the data table generation operation described above, the case where the dynamic range of the solid-state image sensor 2 is switched discretely has been described above. However, in the case where the dynamic range of the solid-state image sensor 2 is continuously switched. The following operation process may be performed. First, the memory 133 stores a plurality of stages of photoelectric conversion characteristics as in the case where the dynamic range of the solid-state imaging device 2 is discretely switched. Then, when the set dynamic range value of the solid-state imaging device 2 (for example, the voltage value VL of the signal φVPS) becomes a value between two discretely set dynamic ranges, it is set discretely. Two photoelectric conversion characteristics for two dynamic ranges are read from the memory 133.

  Then, the dynamic range value set for the solid-state imaging device 2 (for example, the voltage value VL of the signal φVPS) is read from the memory 133 based on the relationship between the two dynamic range values set discretely and 2 A new photoelectric conversion characteristic is generated by interpolating each coefficient (A in equation (7) and α, β in equation (8)) of the two photoelectric conversion characteristics. The photoelectric conversion characteristics generated in this way are used as the G signal photoelectric conversion characteristics for the dynamic range currently set for the solid-state imaging device 2. That is, for example, as in the graph of FIG. 7, four types of data tables for the photoelectric conversion characteristics a1 to a4 of the solid-state imaging device 2 are stored in the memory 133, and the photoelectric conversion between the photoelectric conversion characteristics a2 and a3 is performed. It is assumed that a dynamic range serving as conversion characteristics is set for the solid-state imaging device 2. At this time, the photoelectric conversion characteristics a2 and a3 are interpolated to obtain the photoelectric conversion characteristics ax for the dynamic range currently set for the solid-state imaging device 2, as shown in FIG. Used as a characteristic. Each of the photoelectric conversion characteristics of the RB signal is obtained using the photoelectric conversion characteristics of the G signal thus obtained and the WB evaluation values wr and wb. At this time, the photoelectric conversion characteristic of the RB signal is back-calculated using the photoelectric conversion characteristic of the G signal and the luminance difference at the threshold level Vth obtained from the WB evaluation values wr and wb.

<First Example of WB Control Circuit>
A first example of the WB control circuit in the imaging apparatus configured as shown in FIG. 1 will be described in detail below with reference to the drawings. FIG. 21 is a block diagram showing the internal configuration of the WB control circuit of this example. The WB control circuit of this example is provided with the data tables Dr and Db generated in the first example or the second example of the data table generation operation by the overall control unit.

  As shown in FIG. 21, the WB control circuit 8 of this example includes a signal value conversion unit 81 r that converts the signal level of the R signal from which the FPN component has been removed by the FPN correction circuit 6, and an FPN component that is converted by the FPN correction circuit 6. A signal value conversion unit 81b that converts the signal level of the removed B signal, an LUT (Look Up Table) 82r that stores a data table Dr that represents an input / output conversion value of the signal level of the R signal, and a signal level of the B signal The output timing of the LUT 82b for storing the data table Db representing the input / output conversion values of the RB, the RB signal output from each of the signal value conversion units 81r and 81b, and the G signal from which the FPN component has been removed by the FPN correction circuit 6 is adjusted. And a timing adjustment unit 83.

  When the data tables Dr and Db generated in the microcomputer 132 of the overall control unit 13 are given, the WB control circuit 8 configured as described above stores the data tables Dr and Db in the LUTs 82r and 82b, respectively. When each of the RGB signals corrected by the FPN correction circuit 6 is input to the WB control circuit 8, the R signal is supplied to the signal value conversion unit 81r and the B signal is supplied to the signal value conversion unit 81b. When the signal value conversion unit 81r confirms the signal level of the input R signal, the signal value conversion unit 81r refers to the data table Dr in the LUT 82r, and after correction processing stored for the same input address as the signal level of the input R signal. Read the signal level. Then, the read signal level after the correction process is sent to the timing adjustment unit 83 as a new signal level of the R signal. Similarly, when the signal level conversion unit 81b confirms the signal level of the input B signal, the signal level Db in the LUT 82b is referred to read the signal level after the correction process, and the signal level after the correction process Is sent to the timing adjustment unit 83 as the signal level of the new B signal.

  Therefore, white balance processing based on the G signal is performed in each of the signal value conversion units 81r and 81b. At this time, when the photoelectric conversion characteristics of the input RGB signal are as shown in the graph of FIG. 22A, the input / output relationship of each of the RGB signals is as shown in the graph of FIG. 22B. Become. That is, in FIG. 22B, the input / output relationship of the G signal is a linear relationship. Then, the input / output relationship of the RB signal is in a state where the slope of the input / output relationship of the G signal is changed for the linear conversion characteristic region (linear region) where the photoelectric conversion property overlaps the linear conversion property of the photoelectric conversion property of the G signal, In addition, in the logarithmic conversion characteristic region (logarithmic region) where the photoelectric conversion characteristic overlaps the logarithmic conversion characteristic of the G signal photoelectric conversion characteristic, the input / output relationship of the G signal is translated. In the input / output relationship of the RB signal, the logarithmic conversion characteristic of the photoelectric conversion characteristic overlaps the linear conversion characteristic of the photoelectric conversion characteristic of the G signal, or the logarithmic conversion characteristic of the photoelectric conversion characteristic is linear of the photoelectric conversion characteristic of the G signal. The intermediate region that overlaps with the conversion characteristic is in a state where a combination of multiplication / division of the input / output relationship of the G signal in the linear region and an addition / subtraction of the input / output relationship of the G signal in the logarithmic region are combined.

  Thus, the RB signal converted to the signal level after the correction processing by the signal value conversion units 81r and 81b and the G signal corrected by the FPN correction circuit 6 are input to the timing adjustment unit 83. The timing adjustment unit 83 adjusts the timing for outputting the RB signal converted by the signal value conversion units 81r and 81b and the G signal that is not subjected to the conversion process. The RGB signal whose output timing is adjusted in this way is output to the color interpolation circuit 9 in the subsequent stage, and signal processing corresponding to each pixel can be performed in each circuit in the subsequent stage.

<Second Example of WB Control Circuit>
A second example of the WB control circuit in the imaging apparatus configured as shown in FIG. 1 will be described in detail below with reference to the drawings. FIG. 23 is a block diagram showing the internal configuration of the WB control circuit of this example. The WB control circuit of this example is provided with the data tables Dr and Db generated in the third example of the data table generation operation by the overall control unit. Further, in the WB control circuit shown in FIG. 23, the parts used for the same purpose as those of the WB control circuit of FIG.

  As shown in FIG. 23, the WB control circuit 8 of this example converts the signal level of the G signal from which the FPN component has been removed by the signal value conversion units 81r and 81b, the LUTs 82r and 82b, and the FPN correction circuit 6. The output timing of each of the RGB signals output from the value converter 81g, the LUT 82g for storing the data table Dg representing the input / output conversion values of the signal level of the G signal, and the signal value converters 81r, 81g, 81b is adjusted. A timing adjustment unit 83.

  When the data tables Dr, Dg, Db generated in the microcomputer 132 of the overall control unit 13 are given, the WB control circuit 8 configured as described above converts the data tables Dr, Dg, Db into LUTs 82r, 82g, 82b, respectively. Store. When the RGB signals corrected by the FPN correction circuit 6 are input to the WB control circuit 8, the RGB signals are respectively supplied to the signal value conversion units 81r, 81g, and 81b. Similarly to the first example, the signal value conversion units 81r and 81b refer to the data tables Dr and Db in the LUTs 82r and 82b, and after correction processing stored for the same input address as the signal level of the input RB signal. Is sent to the timing adjustment unit 83 as a new RB signal. Also in the signal value conversion unit 81g, when the signal level of the input G signal is confirmed, the correction is stored with respect to the same input address as the signal level of the input G signal by referring to the data table Dg in the LUT 82g. The processed signal level is read and sent to the timing adjustment unit 83 as a new G signal.

  Therefore, in each of the signal value conversion units 81r and 81b, white balance processing based on the G signal is performed, and gain adjustment and gradation conversion are performed on the RB signal. In the signal value converter 81g, gain adjustment and gradation conversion are performed on the G signal. The timing adjustment unit 83 adjusts the output timing of the RGB signals converted into the signal levels after the correction processing by the signal value conversion units 81r, 81g, and 81b as described above. The RGB signal whose output timing is adjusted in this way is output to the color interpolation circuit 9 in the subsequent stage, and signal processing corresponding to each pixel can be performed in each circuit in the subsequent stage.

  In this embodiment, the solid-state imaging device is operated so as to remove pixel variation in the device by subtracting the noise signal from the image signal, and the FPN component further remaining in the image signal in the FPN correction circuit. However, the FPN correction circuit may be configured to remove all FPN components generated by pixel variation or the like without reading the noise signal in the solid-state imaging device.

  In the present embodiment, a single-plate solid-state image sensor having a plurality of types of color filters provided in one solid-state image sensor is used. For example, a three-plate solid-state image sensor having a solid-state image sensor for each RGB color filter As described above, a solid-state imaging device having the same color filter may be provided for each type of color filter. In the present embodiment, the photoelectric conversion characteristic including the linear characteristic region and the logarithmic characteristic region has been described. However, the present invention is not limited to this. For example, from the first linear conversion characteristic to the first linear conversion characteristic. This applies to what is called an adaptive sensor, such as one that changes to a second linear conversion characteristic having a different slope, or one that includes a linear conversion characteristic and a nonlinear conversion characteristic other than a logarithmic conversion characteristic.

<Imaging system>
In the imaging device described above, various signal processing including white balance processing is performed in the imaging device, but data obtained by the imaging device is given without performing these various signal processes in the imaging device. An imaging system that performs the above-described various signal processes in a computer can also be configured. Hereinafter, an imaging system including such an imaging apparatus and a computer will be described with reference to the drawings.

  As shown in FIG. 24, the imaging system receives an RGB signal output from the imaging device 200 and captures a subject to generate RGB signals, and performs various signal processing including white balance processing. And a computer 250. At this time, the imaging apparatus 200 performs black reference correction and FPN correction on the RGB signal obtained by imaging the subject, and detects an AE evaluation value for setting the exposure amount. On the other hand, the computer 250 detects the WB evaluation value and performs various signal processing after the white balance processing on the RGB signal given from the imaging device 200.

  In such an imaging system, the imaging apparatus 200 includes an optical system 1, a solid-state imaging device 2, an amplifier 3, an AD conversion circuit 4, a black reference correction circuit 5, an FPN correction circuit 6, an aperture control unit 14, and a timing generation circuit 15. An AE evaluation value detection circuit 7a for detecting an AE evaluation value, an overall control unit 13a for controlling each block, a memory 201 for temporarily storing RGB signals corrected by the FPN correction circuit 6, and a memory An input / output interface 202 that reads out the RGB signals temporarily stored in 201 and transmits them to the outside.

  The computer 250 is a PC (Personal Computer), a PDA (Personal Digital Assistant) or the like, and includes a CPU (Central Processing Unit) 251 that performs data processing operations, a memory 252 that temporarily stores data, an application, It includes a hard disk 253 for storing data, an input unit 254 such as a keyboard and mouse for inputting data, a display 255 for displaying video, and an input / output interface 256 for exchanging data with the outside.

  As described above, when the imaging apparatus 200 and the computer 250 are respectively configured, an application for performing various signal processing after the white balance processing on the RGB signals in the computer 250 is stored in the hard disk 253. By reading this application from the hard disk 253 and storing it in the memory 252, it is possible to perform the WB evaluation value detection operation and various signal processing after the white balance processing. Also, by starting this application, a user interface (UI) for the user to specify parameters in various signal processing is displayed on the display 255.

  Hereinafter, operations of the imaging apparatus 200 and the computer 250 in the imaging system will be described with reference to the drawings.

  First, in the imaging device 200, when light is incident on the solid-state imaging device 2, an RGB signal that is an analog signal is generated and amplified by the amplifier 3 as in the imaging device of FIG. The signal is converted into a digital signal by the conversion circuit 4. The RGB signal to be a digital signal is subjected to FPN by subtracting the FPN component stored in the FPN correction circuit 6 after the black level that is the lowest luminance value is corrected to the reference value in the black reference correction circuit 5. Ingredients are removed. Then, the RGB signal from which the FPN component has been removed is stored in the memory 201. When the RGB signal from which the FPN component is removed is given to the AE evaluation value detection circuit 7a when operating in this way, the luminance range of the subject is confirmed and the aperture of the diaphragm 1a set by the diaphragm controller 14 is determined. An AE evaluation value is detected.

In addition, the imaging apparatus 200 checks the dynamic range information indicating the photoelectric conversion characteristics set for the solid-state imaging device 2 when performing the imaging operation for each captured image, and stores it in the memory 201 together with the RGB signal of the image. Store. This dynamic range information includes at least one of the following four pieces of information (1) and (2) and at least one of (3) and (4), or (1) to Only at least one of (4) is provided.
(1) Inflection point Vth of the photoelectric conversion characteristics of the solid-state imaging device 2
(2) Mode number M for setting the photoelectric conversion characteristics of the solid-state imaging device 2
(3) Coefficients A, C, α, β of approximate expressions indicating the photoelectric conversion characteristics of the solid-state imaging device 2
(4) Imaging conditions of the imaging apparatus 200

  In these dynamic range information, the inflection point Vth of the photoelectric conversion characteristic of the solid-state image sensor 2 indicates the signal level of the RGB signal when the photoelectric conversion characteristic logarithmic conversion characteristic of the solid-state image sensor 2 is changed to the linear conversion characteristic. Further, the mode number M for setting the photoelectric conversion characteristics of the solid-state imaging device 2 is set on the computer 250 side, so that the photoelectric conversion characteristics of the solid-state imaging device 2 of the imaging apparatus 200 are set. Is. The coefficients of the approximate expression indicating the photoelectric conversion characteristics of the solid-state imaging device 2 are the coefficients A and C in the equation (a) V = A × L + C representing the linear conversion characteristic, and the equation (b) representing the logarithmic conversion characteristic V = It is constituted by the coefficients α and β in α × ln (L) + β. Further, when the imaging condition of the imaging apparatus 200 is set, the voltage difference ΔVPS between the voltage values VH and VL of the signal φVPS, the exposure time tx to the solid-state imaging device 2, the aperture ratio rx of the diaphragm 1a, and the solid-state imaging device 2 The amplification factor ax of the internal amplifier and the amplifier 3 is dynamic range information. When the imaging conditions of the imaging apparatus 200 are dynamic range information, the relationship between the coefficient A in (A) and (exposure time × aperture ratio of the diaphragm 1a × amplification factor) is known, and (B) The voltage difference ΔVPS between the coefficient β and the signal φVPS and the relationship between the coefficient α and the amplification factor are known.

  When the input unit 254 is operated to read the application from the hard disk 253 and the operation designated by the application is started, the computer 250 displays a UI on the display 255 as shown in FIG. A screen is displayed. On the screen of FIG. 25, an image display area X1 for displaying an image obtained by imaging, an image processing condition setting area X2 for setting image processing conditions such as setting of image sharpness and color shading, Color correction is performed for an image acquisition button X3 for instructing the start of capturing an image captured by the imaging apparatus 200, a WB setting region X4 for setting a photoelectric conversion characteristic that is used as a reference when performing white balance processing. A gradation characteristic display area X5 indicating gradation characteristics after gradation conversion performed on the RGB signal signals is displayed.

  At this time, when the sharpness of the image is changed by operating the scroll bar SB1 in the image processing condition setting region X2, the edge enhancement amount for setting the edge component in the coring circuit 12 is changed, and the scrolling is performed. When the bar SB2 is operated to change the color density of the image, the matrix coefficients a1 to a3, b1 to b3, and c1 to c3 in the color correction process are changed. At this time, the edge enhancement amount obtained based on the dynamic range information given from the imaging device 200 or a matrix coefficient in the color correction processing may be changed as a reference. It may be changed based on the matrix coefficient in the color correction process.

  In addition, when the three option buttons Ob1 to Ob3 are designated in the image processing condition setting area X2, the edge enhancement amounts and matrix coefficients a1 to a3, b1 to b3, c1 to be designated by the scroll bars SB1 and SB2 respectively. The target image to use c3 is designated. That is, when the edge enhancement amount specified by the scroll bars SB1 and SB2 and the use of the matrix coefficients a1 to a3, b1 to b3, and c1 to c3 are specified by the option button Ob1, the obtained image has a photoelectric conversion characteristic. Is performed in both cases of the linear conversion characteristic and the logarithmic conversion characteristic, and when the option button Ob2 is designated, the obtained image is performed only when the photoelectric conversion characteristic is the linear conversion characteristic. In addition, when the option button Ob3 is designated, it indicates that the obtained image is performed only when the photoelectric conversion characteristic is the logarithmic conversion characteristic.

  In addition, by specifying five option buttons Wb1 to Wb5 in the WB setting area X4, WB evaluation values wr and wb for performing white balance processing are set. That is, when the option button Wb1 is designated, the white balance processing is set to be performed using the WB evaluation values wr and wb automatically set based on the RGB signals given from the imaging device 200, and the option button Wb2 When .about.Wb5 is designated, white balance processing is set to be performed using WB evaluation values wr and wb which are preset values. When the option buttons Wb2 to WB5 are designated, the WB evaluation values wr and wb corresponding to the image under the fluorescent lamp, the WB evaluation values wr and wb corresponding to the image under the incandescent lamp, and the outdoor sunny day, respectively. The WB evaluation values wr and wb corresponding to the image at, and the WB evaluation values wr and wb corresponding to the image during outdoor cloudy weather are set.

  In the gradation characteristic display area X5, the displayed gradation characteristic indicates a relationship before and after conversion when gradation conversion is performed on each of the RGB signals subjected to color correction processing. Then, by changing the position of the inflection point that switches from the linear conversion characteristic to the logarithmic conversion characteristic in the displayed gradation characteristic, in the dynamic range, the magnitude of the gradation in the linear region that is a signal by the linear conversion characteristic The gradation level in the logarithmic region that becomes a signal based on the logarithmic conversion characteristic can be set. The position of the inflection point of the gradation characteristic may be set with reference to a position obtained based on dynamic range information given from the imaging device 200, or set with reference to a predetermined position set in advance. It doesn't matter if it is done. Further, a plurality of LUTs indicating gradation characteristics may be provided, and the LUT displayed in the gradation characteristic display region X5 may be changed by switching the LUTs.

  As described above, when the application is activated in the computer 250 and the UI as shown in FIG. 25 is displayed on the display 255, the computer 250 operates according to the flowchart in FIG. It is displayed on the display 255. First, in the computer 250, when the input unit 254 is operated and the image acquisition button X3 in the UI screen is pressed (STEP 1), the imaging apparatus 200 in which the input / output interface 202 is connected to the input / output interface 256 is displayed. A line with the imaging device 200 is secured (STEP 2). At this time, a line can be secured by repeating the communication request and response between the imaging apparatus 200 and the computer 250.

  Then, it is confirmed whether or not a line with the imaging apparatus 200 is secured (STEP 3). When it is confirmed that a line with the imaging apparatus 200 is secured (Yes), the imaging apparatus 200 is imaged. The output of the received RGB signal is requested (STEP 4). At this time, when receiving an RGB signal output request from the computer 250, the imaging apparatus 200 reads the RGB signal and dynamic range information for one frame stored in the memory 201 and outputs them from the input / output interface 202. . At this time, when frame data based on RGB signals for one frame is generated and output, dynamic range information is added to the header portion of the frame data.

  When the frame data from the imaging device 200 is received by the input / output interface 256 and stored in the temporary storage area of the hard disk 253 (STEP 5), dynamic range information is acquired from the header portion of this frame data (STEP 6). . Based on the acquired dynamic range information, parameters used for each signal processing are set, and display corresponding to the set parameters is performed on the UI image of the display 255 (STEP 7).

  That is, WB detection values wr and wb for white balance processing, matrix coefficients a1 to a3, b1 to b3 and c1 to c3 for color correction processing, gradation characteristics for gradation conversion processing, and edge enhancement amounts for coring processing are set. At the same time, display according to each set parameter is performed in each of the image processing condition setting area X2, the WB setting area X4, and the WB setting area X4.

  When each parameter is set in this way, in order to set the WB evaluation values wb and wr used in the white balance processing, first, from the inflection point Vth or mode number M obtained from the dynamic range information, A threshold level Vth (see FIGS. 10 to 12) for determining the photoelectric conversion characteristics of each of the RGB signals is set. At this time, when the inflection point Vth is included in the dynamic range information, the inflection point Vth is set as it is as the threshold level Vth. The threshold level Vth corresponding to the mode number M stored therewith is read out and set.

  For each of the coefficients Ag, C, α, and βg in the equations (a) and (b) showing the photoelectric conversion characteristics of the G signal as a reference for performing white balance processing, the coefficient A obtained from the dynamic range information , C, α, β, or the imaging conditions of the imaging apparatus 200, and the threshold level Vth is set based on the photoelectric conversion characteristics confirmed from the coefficients Ag, C, α, βg. At this time, when the coefficients A, C, α, and β are included in the dynamic range information, the coefficients A, C, α, and β are directly used as the coefficients Ag, C, α, and βg in the equations (a) and (b). To set.

In addition, when the shooting conditions (voltage difference ΔVPS, exposure time tx, aperture ratio rx, amplification factor ax) are included in the dynamic range information, coefficients A0, C0, α0, exposure time tx0, aperture ratio rx0, amplification, which are reference values, are included. The rate ax0 is stored together with the application of the hard disk 253 in advance. The coefficients Ag, C, α, and βg are set by being calculated based on the following formulas (c) to (f). Note that β0 is a value corresponding to the voltage difference ΔVPS of the signal φVPS stored together with the application of the hard disk 253 in advance.
Ag = A0 × (tx / tx0) × (rx / rx0) × (ax / ax0) (C)
C = C0 (D)
α = α0 × (tx / tx0) (e)
βg = β0 × (tx / tx0) (f)

  When the parameters set in this way are given to the application stored in the memory 252, the signal processing according to the set parameters is performed on the RGB signals obtained from the frame data received in STEP 5 by this application. Performed (STEP 8). That is, each signal processing is performed on the RGB signal obtained from the frame data in the order of white balance processing, color interpolation processing, color correction processing, gradation conversion processing, and coring processing. Each signal processing is the same as the signal processing in the imaging apparatus shown in FIG.

  The frame data based on the RGB signals subjected to the signal processing is stored in the hard disk 253, and an image based on the frame data is displayed in the image display area X1 of the display 255 (STEP 9). Then, the input unit 254 is operated, and operations in the image processing condition setting area X2, the WB setting area X4, and the WB setting area X4 are performed, and it is confirmed whether or not each parameter is instructed (STEP 10). . If parameter change is instructed (Yes), each parameter is changed in accordance with the instructed change amount (STEP 11), and then the process proceeds to STEP 8.

  If it is not confirmed in STEP 3 that the line is secured (No), a display indicating that the line is not connected is displayed on the display 255 (STEP 12), and the process proceeds to STEP 2. Further, in STEP 10, when the instruction for changing each parameter is not confirmed (No), the operation is terminated.

  As described above, according to the present system, each signal processing with a calculation load is performed on the computer 250 side, so that the configuration of the imaging apparatus 200 is simplified and the processing speed can be increased. In this system, the signal output from the imaging apparatus 200 to the computer 250 may be not only frame data based on the above-described still image but also frame data or stream data based on a moving image. At this time, when a moving image is formed by a plurality of still image frame data, dynamic range information is recorded in the header of each frame data, and the moving image is generated by stream data that performs image compression on the time axis. In this case, the dynamic range information is transmitted as information different from the stream data.

  Further, in the imaging apparatus 200, the overall control unit 13 a converts the format of frame data or stream data based on RGB signals transmitted to the computer 250 into a compressed image such as JPEG, motion JPEG, or MPEG, and outputs it from the input / output interface 202. It does n’t matter what you do. Further, in the computer 250, the UI displayed on the display 255 displays a histogram of the image displayed in the image display area X1, and a display for identifying the pixel area based on the logarithmic conversion characteristic and the pixel area based on the linear conversion characteristic. You may make it perform.

  In the imaging system of FIG. 24, the imaging apparatus 200 includes the black reference correction circuit 5 and the FPN component correction circuit 6, but the imaging apparatus 200 has the black reference correction circuit 5 and the FPN component from the configuration of FIG. The configuration may be such that the correction circuit 6 is omitted, and the computer 250 performs black reference correction processing and FPN correction processing. At this time, the black level for performing the black reference correction process and the FPN component for performing the FPN correction process may be transmitted together with the dynamic range information.

  Furthermore, when the black reference correction process and the FPN correction process are performed in the computer 250 as described above, the computer 250 may store the black level and the FPN component in the hard disk 253 together with the application. At this time, a plurality of black levels are also stored for the inflection point Vth of the photoelectric conversion characteristics, and the inflection points of the photoelectric conversion characteristics obtained from the prestored black level by the dynamic range information as described above. A black level corresponding to Vth is selected. Further, since the FPN component differs depending on the solid-state imaging device 2 in each imaging device 200, it is stored for each imaging device 200.

  Further, when the computer 250 performs white balance processing, the RGB signal is converted into a signal whose logarithmic conversion characteristics are all photoelectric conversion characteristics or a signal whose linear conversion characteristics are all photoelectric conversion characteristics, and then the white balance processing is performed. It doesn't matter what you do. That is, when all the photoelectric conversion characteristics are converted into signals with logarithmic conversion characteristics, the signal values obtained by the linear conversion characteristics are converted into signal values with logarithmic conversion characteristics, and all the photoelectric conversion characteristics are signals with the linear conversion characteristics. In the case of conversion to, the signal value obtained by the logarithmic conversion characteristic is converted to a signal value by the linear conversion characteristic. Note that the calculation for such conversion processing may be performed with reference to the LUT, or may be performed by an arithmetic expression.

  24, the input / output interface 202 of the imaging apparatus 200 and the input / output interface 256 of the computer 250 are communicatively connected, so that frame data obtained by imaging by the imaging apparatus 200 is transferred to the computer 250. Although the imaging apparatus 200 includes a recording unit that records frame data or stream data on a recording medium such as a flexible disk, a compact flash, or a memory card, the computer 250 uses the frame data or stream of the recording medium. A reproducing unit that reads data may be provided. In this way, frame data or stream data obtained by imaging can be transferred from the imaging device 200 to the computer 250 via the recording medium.

These are block diagrams which show the structure of the imaging device which is embodiment of this invention. These are figures which show the arrangement | sequence of the color filter provided in a solid-state image sensor. These are graphs showing level conversion characteristics for edge components in a coring circuit. FIG. 3 is a circuit block diagram for explaining the overall configuration of the solid-state imaging device. These are circuit diagrams which show one structural example of the pixel which comprises the solid-state image sensor of FIG. These are timing charts showing the operation of the pixel of FIG. These are graphs showing the relationship between the luminance of a subject and the output of a pixel. These are block diagrams which show an example of an internal structure of an AE / WB evaluation value detection circuit. These are block diagrams which show the internal structure of a whole control part. These are graphs showing the relationship between luminance values of RGB signals and signal levels. These are figures for showing operation of a WB evaluation value operation part. These are figures for showing operation of a WB evaluation value operation part. These are block diagrams which show the other example of an internal structure of an AE * WB evaluation value detection circuit. These are figures which show an example of the photoelectric conversion characteristic of the RB signal stored in the memory of a whole control part. These show an example of the production | generation procedure of the data table of a whole control part as a functional block diagram. FIG. 10 is a diagram for explaining a data table generation operation; These show another example of the production | generation procedure of the data table of the whole control part as a functional block diagram. FIG. 5 is a diagram for explaining an operation of generating photoelectric conversion characteristics. These show another example of the production | generation procedure of the data table of the whole control part as a functional block diagram. FIG. 5 is a diagram for explaining an operation of generating photoelectric conversion characteristics. These are block diagrams showing an example of the internal configuration of the WB control circuit. These are graphs showing the input / output relationship of RGB signals in the WB control circuit. These are block diagrams which show the other example of the internal structure of a WB control circuit. These are block diagrams which show the structure of the imaging system which is embodiment of this invention. FIG. 25 is a diagram illustrating an example of a screen displayed on the computer of the imaging system in FIG. 24. FIG. 25 is a flowchart showing a signal processing operation in the computer of the imaging system of FIG. 24.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical system 2 Solid-state image sensor 3 Amplifier 4 AD conversion circuit 5 Black reference correction circuit 6 FPN correction circuit 7 AE / WB evaluation value detection circuit 8 WB control circuit 9 Color interpolation circuit 10 Color correction circuit 11 Gradation conversion circuit 12 Coring Circuit 13 Overall control unit 14 Aperture control unit 15 Timing generation circuit

Claims (17)

A photoelectric conversion characteristic including a first region in which an output signal changes with a first characteristic with respect to an incident light amount and a second region in which an output signal changes with a second characteristic different from the first characteristic with respect to the incident light amount. A solid-state image sensor provided with a plurality of types of color filters, a white balance circuit that performs white balance processing on color signals for each type of the color filter output from the solid-state image sensor, In an imaging apparatus comprising:
The white balance circuit includes a first look-up table that provides, as output data, a signal level in which a shift between the color signals is corrected with respect to the level of the input color signal, and the first look-up table is the first look-up table. An imaging apparatus characterized by being associated with both the first and second characteristics.   The imaging apparatus according to claim 1, wherein the first characteristic is a linear change with respect to an incident light amount.   The imaging apparatus according to claim 1, wherein the second characteristic is a natural logarithmic change with respect to an incident light amount. When one of the plurality of types of color signals is used as a reference first color signal and a color signal other than the reference color signal is used as a second color signal,
The first lookup table is:
The signal level of the second color signal is used as an input address, and the signal level when the photoelectric conversion characteristic in the second color signal is converted into the photoelectric conversion characteristic of the first color signal is used as output data for the input address. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is provided. The white balance circuit includes a second look-up table having the signal level of the first color signal as an input address and the signal level subjected to gradation conversion processing as output data for the input address,
The first look-up table converts the photoelectric conversion characteristic of the second color signal into the photoelectric conversion characteristic of the first color signal and the signal level on which the gradation conversion processing has been performed, and the output data for the input address The imaging apparatus according to claim 4, wherein: The first color that is input from the solid-state image sensor for each type of the second color signal is an evaluation value that represents the relationship between the photoelectric conversion characteristic of the first color signal and the photoelectric conversion characteristic of the second color signal. An evaluation value detection circuit for detecting from the relationship between the signal and the signal level of the second color signal,
It said first look-up table, the imaging apparatus according to claim 4 or claim 5, characterized in that it is generated based on the photoelectric conversion characteristics of the said evaluation value first color signal. In the evaluation value detection circuit, for each type of the second color signal, the evaluation value is obtained based on a relationship between average values of the first color signal and the second color signal given from the solid-state imaging device. The imaging apparatus according to claim 6 , wherein In the evaluation value detection circuit,
For each type of the second color signal,
A first evaluation value is obtained based on the relationship between the average values of the first color signal and the second color signal that have changed with the first characteristic with respect to the amount of incident light applied from the solid-state imaging device. ,
Based on the relationship between the average values of the first color signal and the second color signal that have changed in the second characteristic with respect to the amount of incident light applied from the solid-state imaging device, a second evaluation value is obtained,
An evaluation value representing a relationship between the photoelectric conversion characteristic of the first color signal and the photoelectric conversion characteristic of the second color signal is obtained by weighted addition of the first evaluation value and the second evaluation value. The imaging device according to claim 6 . The weighted addition is based on the relationship between the number of pixels that output a signal that varies with the first characteristic with respect to the incident light amount and the number of pixels that output a signal that varies with the second characteristic with respect to the incident light amount. The imaging apparatus according to claim 8 , wherein a weighting coefficient is set. While determining the photoelectric conversion characteristics of the first color signal based on the dynamic range of the solid-state imaging device,
The photoelectric conversion characteristic of the second color signal, the image pickup apparatus according to any one of claims 6 to claim 9, wherein determining, based on the evaluation value and the photoelectric conversion characteristics of the first color signal. After obtaining the luminance value for each signal level of the second color signal based on the photoelectric conversion characteristics of the second color signal, the obtained signal level for each luminance value is used as the photoelectric conversion characteristic of the first color signal. with output data for the input address determined based imaging apparatus according to any one of claims 4 to claim 10, wherein generating the first look-up table. A photoelectric conversion characteristic including a first region in which an output signal changes with a first characteristic with respect to an incident light amount and a second region in which an output signal changes with a second characteristic different from the first characteristic with respect to the incident light amount. An imaging device including a solid-state image sensor provided with a plurality of types of color filters, and an arithmetic device that performs image processing on an image signal obtained by imaging a subject with the imaging device In an imaging system composed of
From the imaging device, an image signal obtained by imaging with the solid-state imaging device, and dynamic range information indicating photoelectric conversion characteristics set for the solid-state imaging device when outputting the image signal, Output to the arithmetic unit,
When the arithmetic unit performs white balance processing on the color signal for each type of the color filter based on the image signal, it gives a signal level in which a shift between the color signals is corrected as output data and the first and first An imaging system characterized in that processing is performed with reference to a look-up table associated with both of the two characteristics. When one of the plurality of types of color signals is used as a reference first color signal and a color signal other than the reference color signal is used as a second color signal,
The lookup table is
The signal level of the second color signal is used as an input address, and the signal level when the photoelectric conversion characteristic in the second color signal is converted into the photoelectric conversion characteristic of the first color signal is used as output data for the input address. The imaging system according to claim 12, wherein there is an imaging system. In the arithmetic unit,
An evaluation value representing the relationship between the photoelectric conversion characteristic of the first color signal and the photoelectric conversion characteristic of the second color signal is input from the solid-state imaging device for each type of the second color signal. Detected from the relationship between the signal and the signal level of the second color signal,
The imaging system according to claim 12 or 13 , wherein the first look-up table is generated based on the evaluation value and a photoelectric conversion characteristic of the first color signal. In the arithmetic unit, a plurality of evaluation values representing a relationship between the photoelectric conversion characteristics of the first color signal and the photoelectric conversion characteristics of the second color signal are set and stored for each of a plurality of predetermined photographing conditions,
When one of the shooting conditions is selected, the evaluation value corresponding to the selected shooting condition is read, and based on the read evaluation value and the photoelectric conversion characteristic of the first color signal, the imaging system according to any one of claims 12 to claim 14, wherein said first look-up table is generated. The first characteristic, the imaging system according to any one of claims 12 to claim 15, characterized in that a linear change with respect to the amount of incident light. The second characteristic is a natural logarithmic change with respect to an incident light amount.
The imaging device according to any one of claims 12 to 16 .

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