KR101436076B1 - Image processor and data processing method thereof - Google Patents

Abstract

An image processor and a data processing method thereof are disclosed. Junction capacitance of a photo sensing element included in the image sensor can vary depending on a voltage of both ends of photo sensing element. The image processor according to an embodiment of the present invention can compensate for source data output by an image sensor by a capacity correction constant calculated by reflecting a change in the junction capacitance when a gate voltage of a transfer transistor connected to the photo sensing element varies.

Description

≪ Desc / Clms Page number 1 > Image processor and its data processing method &

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processor and a data processing method thereof, and more particularly, to an image processor and a data processing method thereof for correcting a change in a junction capacitance of a photo sensing element according to a gate voltage of a transfer transistor.

Generally, an image sensor refers to an electronic device that converts an image into an electrical signal. Image sensors are typically CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors. CMOS image sensors are fabricated based on CMOS LSI (large scale integration) fabrication processes, while CCD image sensors are fabricated based on specially developed fabrication processes. Because of this, CMOS image sensors can integrate various functional circuits together to better perform the performance of CCD as well as the performance of general CMOS image sensor. The dynamic range is one of the factors that indicate the performance of the image sensor and refers to the brightness range of the image that the image sensor can acquire without loss.

On the other hand, the image processor can receive the source data output by the image sensor, process it, and output the image data. For example, an image processor may generate and output image data by computing a correction constant and source data received from an image sensor to compensate for non-ideal characteristics of the image sensor.

The present invention relates to an image processor and a data processing method thereof, and in particular, it is an object of the present invention to provide an image processor and a data processing method thereof that compensate electrostatic capacitance of a photo sensing element which varies as the gate voltage of a transfer transistor varies .

In order to achieve the above object, an image processor according to an exemplary embodiment of the present invention processes source data output from an image sensor composed of N pixels including a photo sensing element and a transfer transistor connected to the photo sensing element A storage unit for storing a plurality of first and second capacitance correction coefficients calculated by reflecting a change in junction capacitance of the photo sensing device according to a gate voltage of the transfer transistor; And an operation unit for calculating the source data based on the first and second capacity correction constants and outputting image data.

According to an exemplary embodiment of the present invention, the storage unit stores the N offset correction constants calculated reflecting the dispersion of the threshold voltage of the transfer transistor and the N gain correction constants calculated by reflecting the dispersion of the ideal factor And the arithmetic unit may calculate the source data based on the offset correction constant and the gain correction constant to output the image data.

According to an exemplary embodiment of the present invention, the intensity of light absorbed by the image sensor and the source data may be related to a logarithmic function, and the arithmetic operation unit may calculate a sum of the second capacity correction constant and the gain correction constant Multiply the logarithm function, and add the product of the first capacity correction constant and the offset correction constant to the logarithm function to generate the image data.

Meanwhile, a data processing method of an image processor according to an exemplary embodiment of the present invention is capable of processing source data output from an image sensor including N pixels, and at least one of the N pixels Receiving source data corresponding to a pixel; Reading a first and second capacity correction constants corresponding to the source data in a storage unit; And outputting image data by calculating the source data, the first and second correction constants, and the first and second capacitance correction constants may be calculated using a transfer transistor connected to the photo sensing element included in the pixel, The junction capacitance of the photo-sensing device depending on the gate voltage of the photo-sensing device can be reflected.

According to an exemplary embodiment of the present invention, the method may further include reading an offset correction constant and a gain correction constant corresponding to the source data in the storage, and the step of outputting the image data may include: The gain correction constant may be further calculated to output the image data, the offset correction constant may reflect the dispersion of the threshold voltage of the transfer transistor, and the gain correction constant may reflect the dispersion of the anomalous factor .

According to an exemplary embodiment of the present invention, the intensity of the light absorbed by the image sensor and the source data may be in a log function relationship, and the step of outputting the image data may include: Multiplying the logarithmic function by the sum of the gain correction constants; And adding the product of the first capacity correction constant and the offset correction constant to the log function.

According to an exemplary embodiment of the present invention, the method may further include a correction constant determination step performed in the initial operation, wherein the correction constant determination step comprises: photographing a uniform image with the image sensor; Determining the offset correction constant and the gain correction constant based on source data output from the image sensor; And storing the offset correction constant and the gain correction constant in the storage unit.

Meanwhile, an image pickup apparatus according to an exemplary embodiment of the present invention may include an image sensor and an image processor, and the image sensor includes a plurality of pixels including a photo sensing element and a transfer transistor connected to the photo sensing element Gt; A row driver for applying a variable voltage to the gate of the transfer transistor in the pixel array; A read circuit that measures a signal output from the pixel array to generate source data; And a controller for controlling the row driver and the read circuit and outputting a status signal including voltage information of the gate and pixel position information corresponding to the source data, A storage unit for storing a plurality of capacitance correction constants calculated by reflecting a change in junction capacitance of the photo sensing element according to a gate voltage of the transistor and outputting at least one of the plurality of capacitance correction constants in accordance with the status signal; And an operation unit for calculating the source data based on the capacity correction constant and outputting image data.

According to such an image sensor and its data processing method, the image pickup device can vary the gate voltage of the transfer transistor according to the photographing environment, and can reduce the noise generated in the image.

1 is a block diagram showing the structure of an image pickup apparatus according to an exemplary embodiment of the present invention.
Figure 2 is an illustration of an implementation of a pixel circuit included in the pixel array of Figure 1 in accordance with an exemplary embodiment of the present invention.
3 is a graph showing the relationship between the intensity of light according to the gate voltage of the transfer transistor of FIG. 2 and the output voltage of the pixel circuit according to an exemplary embodiment of the present invention.
Figure 4 is a diagram illustrating the characteristics of the pixel circuit of Figure 2, in accordance with an exemplary embodiment of the present invention.
5 is a diagram illustrating an embodiment of the storage unit of FIG. 1 according to an exemplary embodiment of the present invention.
FIG. 6 shows an embodiment of the operation unit of FIG. 1 according to an exemplary embodiment of the present invention.
7 is a block diagram illustrating a system including an imaging device in accordance with an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings without intending to intend to provide a thorough understanding of the present invention to a person having ordinary skill in the art to which the present invention belongs.

1 is a block diagram showing the structure of an image pickup apparatus according to an exemplary embodiment of the present invention. The image pickup apparatus 100 may largely include an image sensor 1000 and an image processor 2000. The image sensor 1000 can be exposed to an image, generate an electrical signal according to an image, and output source data according to an electrical signal. The image processor 2000 can receive the source data output by the image sensor 1000, and can calculate and output image data to and from the source data.

1, the image sensor 1000 may include a pixel array 1100, a row driver 1200, a lead circuit 1300, and a controller 1400. [ Pixel array 1100 may include N pixels, and each pixel may comprise a pixel circuit. The pixel circuit can generate an electrical signal according to the intensity of the light incident on the pixel circuit. The pixel circuit may include a photo sensing device and a peripheral circuit, and the photo sensing device may include a photodiode, a photogate, a phototransistor, and the like. Hereinafter, it is assumed that the photo-sensing device is a photodiode, but the present invention is not limited thereto. Details of the pixel circuit will be described later.

The row driver 1200 may apply a plurality of signals to the pixel array 1100 to control the pixel circuits included in the pixel array 1100. For example, the row driver 1200 controls the gate voltage of the transfer transistor so that the charge corresponding to the light absorbed by the photo sensing element included in the pixel circuit is controlled to be output to the outside in accordance with the accumulated or accumulated charge can do.

In accordance with an exemplary embodiment of the present invention, the row driver 1200 may include a variable voltage output 1210. The variable driver 1210 can output M different voltages and the row driver 1200 supplies the voltage output from the variable voltage output unit 1210 to the transfer transistor 1210 included in the pixel circuit of the pixel array 1100, Can be applied to the gate voltage of FIG. When the gate voltage of the transfer transistor is varied, the sensitivity of the image sensor according to the brightness of the light in the dynamic range can be changed. Details of this will be described later.

The read circuit 1300 can receive and measure the signal output from the pixel array 1100, and output the source data according to the measured result. For example, the read circuit may include a plurality of analog-to-digital converters (ADCs), and the ADC receives a voltage, which is an analog signal output from the pixel array 1100, It can be output as digital data.

On the other hand, since the number of ADCs that the read circuit 1300 can measure at the same time is limited, rather than simultaneously measuring the electrical signals output by all of the pixel circuits included in the pixel array 1100, It is possible to sequentially measure the electrical signals for the pixel circuits of the pixels. For example, the read circuit can simultaneously measure an electrical signal output from a pixel circuit included in one row of the pixel array 1100, and output the source data obtained by measuring the electrical signal.

The controller 1400 controls the row driver 1200 and the read circuit 1300 so that the pixel array 1100 is exposed to an image to generate an electrical signal and to measure the generated electrical signal. For example, the control unit 1400 may control the row driver 1200 to output an electrical signal corresponding to the light absorbed by all the pixel circuits included in the pixel array 1100. Also, the control unit 1400 can control the read circuit 1300 to receive and measure the electrical signal output from the pixel array 1100.

According to an exemplary embodiment of the present invention, controller 1400 may output a status signal. The status signal may include information on the source data output by the current read circuit. For example, the status signal may include information on the gate voltage value of the transfer transistor output from the variable voltage output section 1210 of the row driver 1200, and may correspond to the source data output from the current read circuit 1300 And may include information on the position of the pixel circuit. That is, the status signal may include a number of not less than 1 and not more than M as information on the gate voltage of the transfer transistor, and may include a row including a pixel circuit corresponding to the source data output by the read circuit as information on the position of the pixel circuit May be included.

As shown in FIG. 1, the image processor 2000 may include a storage unit 2100 and a computing unit 2200. According to an exemplary embodiment of the present invention, the storage unit 2100 may store a capacity correction constant 2110, receive a status signal from the control unit 1400 of the image sensor 1000, The constant 2110 can be output. The capacity correction constant 2110 may reflect a change in the junction capacitance of the photo-sensing device as the transfer transistor gate voltage of the pixel circuit included in the pixel array 1100 is changed. For example, the storage unit 2100 may store M capacitance correction constants 2110, and based on the information on the gate voltage of the transfer transistor included in the status signal received from the control unit 1400, It is possible to output a corresponding capacity correction constant.

The arithmetic operation unit 2200 can calculate the source data output from the read circuit 1300 of the image sensor 1000 and the capacitance correction constant output from the storage unit 2100 and output the image data. The image data is data that is finally generated according to an image captured by the image capturing apparatus 100. For example, a digital image file can be generated based on image data. The arithmetic operation unit 2200 can generate the image data by reflecting the change in the junction capacitance of the photo-sensing element according to the gate voltage of the transfer transistor by calculating the source data and the capacitance correction constant, The error due to the change can be reduced.

Figure 2 is an illustration of an implementation of a pixel circuit included in the pixel array of Figure 1 in accordance with an exemplary embodiment of the present invention. The pixel array 1110 of the image sensor may include a component that amplifies the electrical signal converted by the photo-sensing device, and this pixel circuit 1110 is referred to as an active pixel sensor (APS). The pixel circuit 1110 can receive a plurality of signals RST, TG, and SEL from the row driver 1200 of FIG. 1 and output an electrical signal VOUT according to the absorbed light.

As shown in FIG. 2, the pixel circuit 1110 may include a photodiode PD, a transfer transistor M_TG, a source-follower transistor M_SF, and a select transistor M_SEL. In this embodiment, the pixel circuit 1110 includes a photodiode PD as a photo sensing element. The photodiode PD is a kind of photo-sensing device having a characteristic that the photocurrent I _ph linearly increases in accordance with the intensity of the input light in the reverse bias state. The photodiode PD is exposed to light Charges (e. G., Electrons) can accumulate when electrically floating from the outside. As the charge accumulates, the cathode voltage of the photodiode PD can be reduced and the intensity of the light absorbed by the photodiode PD can be sensed by measuring the reduced voltage.

The transfer transistor M_TG may couple or block the photodiode PD with floating diffusion (FD) depending on the gate voltage. While the photodiode PD accumulates charge in response to light, a voltage is applied to the gate of the transfer transistor to turn off the transfer transistor so that the photodiode PD and the floating diffusion FD It can be electrically disconnected. When the photodiode PD finishes absorbing the light, the transfer transistor may be turned on to output a voltage change due to the charge accumulated in the photodiode PD, and thus the photodiode PD PD can be transferred to a floating diffusion (FD).

Before the voltage of the photodiode PD is transferred to the floating diffusion FD, the floating diffusion FD is reset by the turn-on reset transistor M_RS. The reset voltage of the floating diffusion FD is amplified through the source-follower transistor M_SF and output to the outside when the selection transistor M_SEL is turned on. The read circuit 1300 of Fig. 1 receives an analog voltage corresponding to the reset voltage of the floating diffusion FD output to the outside.

When the output to the reset voltage of the floating diffusion FD is completed, the reset transistor M_RS is turned off and the transfer transistor M_TG is turned on so that the voltage corresponding to the charge accumulated by the photodiode PD Diffusion (FD). Like the reset voltage of the floating diffusion FD, the changed voltage of the floating diffusion FD is output to the outside through the source-follower transistor M_SF and the selection transistor M_SEL. The read circuit receives the analog voltage corresponding to the voltage change of the floating diffusion FD output to the outside.

The read circuit receives the reset voltage of the floating diffusion FD and the voltage due to the photodiode PD and calculates the amount of light sensed by the photodiode PD through the difference of the positive voltage. Such an operation is called CDS (correlated double sampling), and the order of receiving the reset voltage and the voltage due to the photodiode PD may be changed. Also, in Fig. 2, the pixel circuit is shown as including an NMOS transistor, but this is illustrative, and the pixel circuit may comprise a PMOS transistor.

On the other hand, by adjusting the gate voltage of the transfer transistor M_TG, the change characteristic of the voltage with respect to the intensity of light absorbed by the photo sensing element can be changed. For example, a middle voltage between the voltage for turning on the transfer transistor M_TG and the voltage for turning off the transfer transistor M_TG may be applied to the gate of the transfer transistor M_TG. In this case, the amount of charges accumulated by the photodiode PD increases linearly with respect to the intensity of the absorbed light, and the amount of charge accumulated by the photodiode PD increases according to the voltage accumulated in the vicinity of the threshold voltage according to the voltage applied to the gate of the transfer transistor M_TG When a voltage is reached, the amount of charge accumulated can be a logarithmic function of the intensity of the light absorbed. That is, using the sub-threshold characteristic of the transfer transistor M_TG, the intensity of light and the amount of accumulated charge may have a linear relationship and a logarithmic function relationship. Through this, it is possible to increase the sensitivity of the image sensor by using a linear relationship with respect to the dark image, and to extend the dynamic range of the image sensor by using the log function relationship with respect to the bright image.

Equations (1) and (2) below represent the linear relationship and the logarithmic function relationship with respect to the output voltage of the pixel circuit according to the intensity of light. In the expressions (1) and (2) below, t _int time a photodiode is exposed to light storing an electric charge, V _th is the threshold voltage of the transfer transistor (M_TG), n is at least of the transfer transistor (M_TG) factor (ideal factor) , And T represents the temperature.

As shown in Equations (1) and (2), the output voltage Vout of the pixel circuit 1110 can exhibit a linear response characteristic to the intensity of light when the intensity of light is weak, Characteristics.

3 is a graph showing the relationship between the intensity of light according to the gate voltage of the transfer transistor of FIG. 2 and the output voltage of the pixel circuit according to an exemplary embodiment of the present invention. The results for the case where four different voltages (V _{TG _ mid} ) are applied to the gate of the transfer transistor M_TG of FIG. 2 are shown, the abscissa of the graph represents the intensity of light in log units, The digital value of the ADC measured by the magnitude of the analog voltage output by the pixel circuit 1110 of FIG.

As shown in FIG. 3, the pixel circuit outputs a linearly increasing voltage as the intensity of the absorbing light increases, and may increase while forming a relationship of logarithmic functions when the intensity of the absorbing light is greater than a specific light intensity. In this case, the point at which the relationship between the intensity of light and the output voltage changes from a linear relationship to a logarithmic function relationship is called an inflection point or knee point. As shown in FIG. 3, the position of the inflection point may change as the voltage (V _{TG_mid} ) applied to the gate of the transfer transistor M_TG of FIG. 2 changes. That is, as the gate voltage (V _{TG _ mid} ) of the transfer transistor M_TG rises, the intensity of the maximum light that can accumulate the charge linearly with the intensity of the absorbed light decreases, Lt; / RTI > Using this characteristic, the image pickup apparatus 100 of FIG. 1 can shoot an image by adjusting the gate voltage of the transfer transistor M_TG according to the brightness of the image to be photographed. For example, when the image sensing apparatus 100 captures an image with a dark brightness, the control section 1400 of FIG. 1 controls the row driver 1200 to control the row driver 1200 so that the voltage of the transfer transistor M_TG output from the variable voltage output section 1210 The gate voltage can be reduced, and thus the section in which the output voltage linearly increases with respect to the light intensity can be extended.

On the other hand, in the plurality of pixel circuits included in the pixel array 1100 of FIG. 1, the threshold voltages of the transfer transistors included in each pixel circuit may not be constant. That is, the threshold voltage value of the transfer transistor may include scattering. Further, the abnormal factors shown in the equations (1) and (2) may also include scattering. The scattering may cause fixed pattern noise in the image data. The matrix A is an offset matrix containing information on the threshold voltage dispersion of the transfer transistor M_TG included in each pixel circuit, and the matrix B is an offset matrix including information on each pixel D is the logarithmic response of each pixel circuit, I is the photocurrent generated by the photodiode (PD) due to the movement of the charge absorbed by the photodiode (PD) .

The matrices A and B may each include as elements an equal number of correction constants as the number of pixel circuits included in the pixel array 1100 of FIG. The matrices A and B can be determined based on the source data output by the read circuit by shooting a uniform image, and can be stored in the storage unit 2100 of FIG. The image processor 2000 can predict the response characteristics of all the pixel circuits through the matrixes A and B, and can use it to correct the fixed pattern noise.

Figure 4 is a diagram illustrating the characteristics of the pixel circuit of Figure 2, in accordance with an exemplary embodiment of the present invention. As described above, by changing the gate voltage of the transfer transistor, the image pickup apparatus can photograph images more adaptively. However, as shown in FIG. 4, the junction capacitance of the actual photodiode can be kept constant, regardless of the voltage across the photodiode, and can vary as shown in Equation (4) below. In Equation 4, Q _T is the total amount of charge, ε _Si is the dielectric constant of Si, N _A and N _D is a dopant concentration, V _bi of the respective acceptor (acceptor) and donor (donor) are built-in (built-in) Voltage.

According to Equation (4), FIG. 4 shows a model of a practical photodiode. As shown in FIG. 4, since the junction capacitance of the actual photodiodes does not vary according to the voltage across the photodiode but varies with the relationship of Equation (4), as the gate voltage of the transfer transistor changes The aforementioned scattering characteristics may change.

Equation (5) applies Equation (4) to Equation (2), which indicates that the value of the junction capacitance of the photodiode depends on V _PD and the output voltage according to the logarithmic function response changes.

Since the gate voltage of the transfer transistor determines the V _PD level of the logarithmic function response, the scattering of the gate voltage of the transfer transistor can be regarded as the same as the dispersion of V _PD . Also, looking at Equations 2 and 5, the change in the junction capacitance of the photodiode affects both the threshold voltage V _th and the value of the anomaly factor n, which cause fixed pattern noise of the logarithmic function response Able to know. Using the above relationship, Equation (6) below is simply expressed by including the influence of the gate voltage of the transfer transistor. In particular, in Equation (6),? And? Are correction constants determined by the gate voltages of the transfer transistors, respectively, and are referred to as capacitance correction constants.

5 is a diagram illustrating an embodiment of the storage unit of FIG. 1 according to an exemplary embodiment of the present invention. The storage unit 2100 may store a plurality of correction constants to compensate for source data output by the image sensor, thereby reducing the influence of non-ideal elements. For example, as shown in FIG. 5, the storage unit may store the matrices A and B of Equation (3) and may store? And? Reflecting the influence of the gate voltage of the transfer transistor.

When the pixel circuit included in the pixel array 1100 of FIG. 1 is arranged in the form of rows and columns of x and y, respectively, as shown in FIG. 5, the storage unit 2100 includes x by y matrix A and B can be stored. That is, when the pixel array 1100 is composed of N (x * y) pixels in total, the storage unit 2100 may store matrices A and B each having N correction constants as elements. The correction constants contained in matrices A and B may correspond to each pixel circuit included in the pixel array 1100. [ As described above, the matrix A may include an offset correction constant calculated reflecting the threshold voltage dispersion of the transfer transistor, and the matrix B may include a gain correction constant calculated reflecting the dispersion of the ideal factor.

According to an exemplary embodiment of the invention, the storage 2100 of the image processor 2000 shown in Figure 1 may further store the capacity correction constants [alpha] and [beta]. For example, as shown in FIG. 5, the imaging device in this embodiment can apply a total of M different voltages to the gates of the transfer transistors, so that M different _{1 to M} and _{1 to M} Can be stored. The storage unit 2100 can receive a status signal from the control unit 1400 of FIG. 1 and output a correction constant corresponding to the source data output from the read circuit 1300.

On the other hand, according to an exemplary embodiment of the present invention, the correction constants contained in matrices A and B may be values derived with a specific voltage applied to the gate of the transfer transistor. In this case, the storage unit 2100 may store the values of? _Z and? _Z (1? _Z ? M) corresponding to the specific gate voltage as 1 and 0, respectively.

FIG. 6 shows an embodiment of the operation unit of FIG. 1 according to an exemplary embodiment of the present invention. 1 and 6, the operation unit 2200 can receive the correction constants a _ij , b _ij , α _k , and β _k from the storage unit 2100, S _ij ). 6, the operation unit 2200 performs an operation corresponding to Equation (6) based on the correction constants a _ij , b _ij ,? _K , and? _K and the source data S _ij , A log function calculator LOG, two adders ADDER and two multipliers MULTIPLIER to output the data D _ij . I in Equation 6 can correspond to the source data S _ij outputted by the read circuit 1300 as a photocurrent which increases with the intensity of light.

7 is a block diagram illustrating a system including an imaging device in accordance with an exemplary embodiment of the present invention. System 200 may be any of a computing system that requires image storage, a camera system, a scanner, a vehicle navigation, a video phone, a security system, or a motion detection system.

7, the system 200 includes a central processing unit (or processor) 210, a non-volatile memory 220, an imaging device 230, an input / output device 240 and a RAM 250 . The central processing unit 210 can communicate with the nonvolatile memory 220, the image capture device 230, the input / output device 240 and the RAM 250 via the bus 260. The imaging device 230 may be implemented as an independent semiconductor chip or may be implemented as a single semiconductor chip in combination with the central processing unit 210. The imaging device 230 included in the system 200 shown in FIG. 7 may include the image sensor or image processor described above in accordance with the illustrative embodiments of the present invention. That is, the control unit of the image sensor can output a status signal including information of the source data outputted by the read circuit. The storage unit of the image processor may store correction constants including a capacity correction constant, and may output a correction constant corresponding to the source data in accordance with the status signal. The operation unit of the image processor can calculate the source data and the correction constant and output the image data compensating for the change in the junction capacitance of the photodiode according to the gate voltage of the transfer transistor.

The foregoing description of the embodiments is merely illustrative of the present invention with reference to the drawings for a more thorough understanding of the present invention, and thus should not be construed as limiting the present invention. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the basic principles of the present invention.

Claims (8)

An image processor comprising:
The image processor processes source data output by an image sensor composed of N pixels including a photo sensing element and a transfer transistor connected to the photo sensing element,
A storage unit for storing a plurality of first and second capacitance correction coefficients calculated by reflecting a change in junction capacitance of the photo-sensing device according to a gate voltage of the transfer transistor; And
And an arithmetic unit for calculating the source data based on the first and second capacity correction constants and outputting image data. The method according to claim 1,
Wherein the storage unit further stores N gain correction constants calculated by reflecting dispersion of N offset correction coefficients and ideal factors calculated by reflecting dispersion of a threshold voltage of the transfer transistor,
Wherein the arithmetic unit calculates the source data based on the offset correction constant and the gain correction constant and outputs the image data. 3. The method of claim 2,
Wherein the intensity of the light absorbed by the image sensor and the source data are in logarithmic relation,
The operation unit
Multiplying the logarithmic function by the sum of the second capacity correction constant and the gain correction constant,
And adding the product of the first capacity correction constant and the offset correction constant to the log function to generate the image data. A method of processing source data output by an image sensor comprising N pixels,
Receiving source data corresponding to at least one of the N pixels from the image sensor;
Reading a first and second capacity correction constants corresponding to the source data in a storage unit; And
Calculating the source data, the first and second capacity correction constants, and outputting the image data,
Wherein the first and second capacitance correction constants reflect the junction capacitance of the photo-sensing device according to a gate voltage of a transfer transistor connected to the photo-sensing device included in the pixel. 5. The method of claim 4,
And reading the offset correction constant and the gain correction constant corresponding to the source data in the storage unit,
Wherein the step of outputting the image data further includes calculating the offset correction constant and the gain correction constant to output the image data,
Wherein the offset correction constant reflects a dispersion of a threshold voltage of the transfer transistor,
Wherein the gain correction constant reflects the disparity of the anomaly factor. 6. The method of claim 5,
Wherein the intensity of the light absorbed by the image sensor and the source data are in logarithmic relation,
The step of outputting the image data
Multiplying the logarithmic function by the sum of the second capacity correction constant and the gain correction constant; And
And adding a product of the first capacity correction constant and the offset correction constant to the log function. 6. The method of claim 5,
Further comprising a correction constant determination step performed in the initial operation,
Wherein the correction constant determination step comprises:
Photographing a uniform image with the image sensor;
Determining the offset correction constant and the gain correction constant based on source data output from the image sensor; And
And storing the offset correction constant and the gain correction constant in the storage unit. An imaging device comprising an image sensor and an image processor,
Wherein the image sensor comprises:
A pixel array including a plurality of pixels including a light sensing element and a transfer transistor coupled to the photo sensing element;
A row driver for applying a variable voltage to the gate of the transfer transistor in the pixel array;
A read circuit that measures a signal output from the pixel array to generate source data; And
And a controller for controlling the row driver and the read circuit and outputting a status signal including voltage information of the gate and pixel position information corresponding to the source data,
The image processor comprising:
A storage capacitor for storing a plurality of capacitance correction constants calculated by reflecting a change in junction capacitance of the photo-sensing element according to a gate voltage of the transfer transistor, and outputting at least one of the plurality of capacitance correction constants according to the status signal; ; And
And an arithmetic unit for calculating the source data based on the capacity correction constant and outputting image data.

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