KR20070039677A - System and method of auto exposure control - Google Patents

Abstract

The present invention relates to an automatic exposure control apparatus and a method thereof, and by only generating an index of the table according to the generation of a table for automatic exposure control, the automatic exposure control time can be shortened, and the microprocessor algorithm can be easily implemented. There is an advantage.

The automatic exposure control apparatus according to the present invention is an automatic exposure control apparatus that automatically adjusts an image sensor exposure time at intervals of one or more frames per resolution mode, and forms an index and stores values corresponding to a predetermined item in the index. A table generator for generating a table; A distribution calculator calculating a distribution of brightness components; Correcting the difference between the brightness average value and the target brightness value for a frame of a predetermined period currently input using the distribution chart calculated by the distribution calculator, and using the corrected value, the image sensor exposure time from the table. And an index selector for selecting an index in which values necessary to adjust the value are stored.

Auto Exposure Exposure, Table, Auto Exposure Evaluation, Digital Amplification Ratio, Index

Description

Automatic exposure control device and its method {SYSTEM AND METHOD OF AUTO EXPOSURE CONTROL}

1 is a block diagram of an automatic exposure control apparatus according to the present invention

2 is a block diagram of a table generation unit according to the present invention.

3 is a view showing a storage area of the distribution chart calculating unit according to the present invention;

4 is a block diagram of an index selector according to the present invention.

5 is a flowchart of an automatic exposure control method according to the present invention.

6 is a flow chart of the first step according to the present invention

7 is a flow chart of the third step according to the present invention

8 is a flowchart of a fourth step according to the present invention.

<Description of Major Symbols in Drawing>

100: automatic exposure control apparatus according to the present invention

110: table generation unit 111: mode conversion control unit

112: distribution chart control unit 113: exposure unit basic unit calculation unit

114: Table Generation Engine 115: Table Completion Register

116: interface engine 117: sensor interface engine

120: distribution chart calculation 130: index selector

131: automatic exposure control unit 132: average level calculation unit

133: error calculation unit 134: cumulative error calculation unit

135: index search unit 136: pause detection unit

137: distribution calculator register

The present invention relates to an automatic exposure control apparatus and a method thereof, and by only generating an index of the table according to the generation of a table for automatic exposure control, the automatic exposure control time can be shortened, and the microprocessor algorithm can be easily implemented. An automatic exposure control apparatus and method thereof are provided.

Recently, mobile phones equipped with digital cameras and camera modules are becoming more common. In current digital cameras or mobile phone digital cameras, the default exposure mode is Auto Exposure Control, which automatically adjusts the exposure time of the image sensor without manual exposure.

That is, automatic exposure control for shortening the exposure time of the sensor to light when the light is bright and to increase the exposure time to the light of the sensor when the light is dark is ISP (Image Signal Processing) or DSP (Digital Signal Processing). Is being performed on.

In addition, digital cameras for mobile phones and digital cameras currently on the market have a preview mode and a capture mode.

Here, the preview mode is a mode for outputting an image of several tens to tens of frames per second through the LCD, and the capture mode is a mode for storing the image of the instant in the memory when the user presses the save button.

In general, a digital camera or a digital camera for a mobile phone outputs the LCD to a low resolution in the preview mode, and converts the image to a high resolution in the capture mode to store a high resolution image.

However, the image sensor clock and register settings when operating at low resolution in preview mode and the image sensor clock and register settings when operating at high resolution in capture mode are often different. The characteristics when operating and the image sensor operating at high resolution in capture mode are often different.

 Therefore, when a user of a digital camera or a digital camera for a mobile phone views the preview image on the LCD and then presses the save button, the automatic exposure control or the automatic white balance control must be re-configured according to the converted mode. The image that is actually stored will be saved hundreds to thousands of ms after pressing the save button.

The automatic exposure control method according to the prior art calculates a difference between the brightness of the currently output frame and the target brightness, calculates a compensation value for correcting the difference, and then adds the compensation value to the current exposure conversion value in the future. When the applied value is obtained and the image sensor is in the high resolution mode, the future applied value is approximated to a multiple of the minimum exposure time, and the approximated multiple value is transmitted to the sensor, and the insufficient compensation value is converted to the digital amplification ratio to the ISP. It was how to do it.

However, the automatic exposure control method according to the prior art as described above has a problem in that the automatic exposure control time is required because the exposure time of the image sensor must be adjusted for each frame in each resolution mode.

In addition, since the exposure time of the image sensor must be adjusted for each frame in each resolution mode, it is difficult to implement an algorithm of the microprocessor.

Accordingly, the present invention has been made to solve the above problems, and since only the index of the table needs to be calculated as a table for automatic exposure control is generated, the automatic exposure control time can be shortened, and the microprocessor algorithm can be easily implemented. An automatic exposure control apparatus and method are provided.

An automatic exposure control apparatus according to the present invention for achieving the above object, in the automatic exposure control apparatus for automatically adjusting the image sensor exposure time at the interval of one or more frames for each resolution mode, forming an index, a predetermined item in the index A table generator for storing a value corresponding to the table and generating a table; A distribution calculator calculating a distribution of brightness components; Correcting the difference between the brightness average value and the target brightness value for a frame of a predetermined period currently input using the distribution chart calculated by the distribution calculator, and using the corrected value, the image sensor exposure time from the table. And an index selector for selecting an index in which values necessary to adjust the value are stored.

The table generation unit may include: a mode conversion controller configured to receive a mode conversion command from a DSP to convert resolution modes of an ISP and an image sensor, and to calculate a brightness component distribution of the distribution calculator and to control image data output from the image sensor; A distribution controller which receives a command from the mode conversion controller and controls the distribution calculator; An exposure time basic unit calculator for dividing an exposure time basic unit converted into a number of clocks by the image sensor by a clock frequency and converting it into time; A table generation engine that obtains an image sensor exposure time for a frame of a period immediately before mode conversion by using the exposure time basic unit converted by the exposure time basic unit calculator, and generates a table for the converted mode; And a table completion register which is reset when the mode is changed and is set when the table is generated.

In this case, the table generation engine generates a table such that the image sensor exposure time of the frame of the first period after the mode conversion is substantially the same as the image sensor exposure time of the frame of the period immediately before the mode conversion.

The table generation engine may generate a table including an automatic exposure evaluation value obtained by dividing the exposure time of the image sensor by the basic unit of exposure time and a digital amplification ratio item which is a brightness amplification ratio of the ISP.

The table generation engine may generate a table in which 100 pairs of automatic exposure evaluation values and digital amplification ratios are stored in the formed indexes.

The index selector may include: an average level calculator configured to calculate a brightness average level value by using the brightness distribution calculated by the distribution calculator; An automatic exposure control unit which resets the completion register of the distribution calculator, or resets the distribution calculator completion register 136 and operates the average level calculator; An error calculator configured to calculate a brightness error that is a difference between the brightness average level value and a target brightness value; A cumulative error calculator configured to calculate a cumulative value for a brightness error of a frame inputted before; Obtain a limit of the brightness error that can be corrected by using the calculated cumulative error of the brightness error, and using the brightness error limit value is stored the automatic exposure evaluation value and the digital amplification ratio for the frame of the current input period An index search unit for searching an index; And a pause detector detecting whether an ISP state for a frame of a predetermined period currently being input is a pause.

On the other hand, the mode conversion controller, when the ISP state is idle, characterized in that for setting the automatic exposure evaluation value stored in the index found in the index search unit to the image sensor.

The mode conversion controller may set the digital amplification ratio stored in the index searched by the index search unit to the ISP when the ISP state is idle.

The mode conversion controller may be configured to stop the image data output for the mode immediately before the conversion and to output the image data for the converted mode.

The mode conversion controller may be configured to, by the distribution control unit, control the distribution calculator to stop calculating the distribution of the brightness components for the mode immediately before the conversion and to calculate the distribution of the brightness components for the converted mode. do.

On the other hand, the automatic exposure control method according to the present invention for achieving the above object, in the automatic exposure control method for automatically adjusting the image sensor exposure time at intervals of one or more frames per resolution mode, forming an index, A first step of generating a table by storing values corresponding to a predetermined item; Calculating a distribution of brightness components; The difference between the brightness average value and the target brightness value for the frame which is currently input is corrected using the distribution chart calculated in the second step, and the image sensor exposure time is determined from the table using the corrected value. Selecting an index in which values necessary to adjust are stored; And a fourth step of adjusting the exposure time of the image sensor by using values stored in the index selected in the third step.

Here, the first step may include a first to first step of delivering a mode conversion command received from the DSP; Resetting the completion register of the table for the mode immediately before conversion; Stopping the calculation of the distribution of the brightness components for the mode immediately before the conversion; 1-4 steps of stopping output of the image data from the image sensor for the mode immediately before conversion; 1-5 step of converting the resolution of the image sensor; First to sixth steps of converting the resolution of the ISP; A first to seventh steps of dividing an exposure time basic unit converted into a number of clocks by the image sensor by a clock frequency and converting the result into time; Calculating an image sensor exposure time for a frame of a period immediately before mode conversion by using the converted exposure time basic unit; And forming an index and generating a table by storing values corresponding to a predetermined item in the index; And setting the completion register of the table for the converted mode when the table is generated.

In this case, the steps 1-9 may further include generating a table such that the image sensor exposure time for the frame of the first period after the mode conversion is substantially the same as the image sensor exposure time for the frame of the period immediately before the mode conversion. It features.

In addition, in the step 1-9, the table is generated such that the image sensor exposure time divided by the exposure time basic unit is divided into a digital amplification ratio item which is the brightness amplification ratio of the ISP and the item. do.

In addition, the step 1-9, characterized in that for generating the table to store the automatic exposure evaluation value and the digital amplification ratio consisting of 100 pairs in each formed index.

The third step may include: an average level calculator configured to reset the completion register of the distribution calculator that performs the second step or reset the completion register of the distribution calculator that performs the second step and calculate a brightness average level value. Operating step 3-1; A third step of calculating a brightness average level value using the brightness distribution calculated in the second step; Calculating a brightness error which is a difference between the brightness average level value and a target brightness value; Calculating a cumulative value for a brightness error of a frame inputted before; Calculating a threshold of brightness errors that can be corrected using the accumulated values of the calculated brightness errors; Searching for an index in which an automatic exposure evaluation value and a digital amplification ratio are stored for a frame which is currently input using the calculated brightness error threshold value; And 3-7 determining whether an ISP state for a frame of a predetermined period that is currently input is at rest.

In this case, the step 3-7, if the status of the ISP for the frame of the current input period is in the idle state, the process proceeds to the fourth step, and if it is not the idle period is fed back to the 3-7 stage It is done.

On the other hand, the fourth step may include a step 4-1 of setting the automatic exposure evaluation value stored in the index searched in the step 3-6 to the image sensor; Step 4-2 of setting the digital amplification ratio stored in the index found in steps 3-6 to the ISP; Adjusting the exposure time of the image sensor using the set automatic exposure evaluation value and the digital amplification ratio; A fourth step of performing a calculation of distribution of brightness components for the mode converted according to the adjusted exposure time; And a fourth step of performing image data output from the image sensor for the mode converted according to the adjusted exposure time.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an automatic exposure control apparatus 100 according to the present invention. As shown in FIG. 1, the automatic exposure control apparatus 100 according to the present invention exposes an image sensor at one or more frames per resolution mode. As an apparatus for automatically adjusting the time, the apparatus includes a table generator 110, a distribution chart calculator 120, and an index selector 130.

Here, the table generator 110 forms an index and generates a table by storing values corresponding to a predetermined item in the index.

2 is a block diagram of the table generator 110 according to the present invention. As shown in FIG. 2, the table generator 110 includes a mode conversion controller 111, a distribution chart controller 112, and an exposure time. The basic unit calculation unit 113, the table generation engine 114, and the table completion register 115 are configured.

Here, the mode conversion control unit 111 receives a mode conversion command from the DSP through the interface engine 116 between the DSP and the ISP, decodes the command, and converts the resolution modes of the ISP and the image sensor. The brightness component distribution diagram of the distribution calculator 120 and the image data output from the image sensor are controlled.

In addition, the distribution control unit 112 serves to control the distribution calculation unit 120 by receiving a command from the mode conversion control unit 111.

In addition, the exposure time basic unit calculator 113 divides the exposure time basic unit converted into the number of clocks by the image sensor through the sensor interface engine 117 by dividing the clock frequency into a time.

At this time, the base unit of exposure time converted into time is defined as EXP_basetime, which will be described later.

Meanwhile, the table generation engine 114 calculates an image sensor exposure time for a frame of a period immediately before the mode conversion, using the EXP_basetime converted by the exposure time base unit calculator 113.

At this time, the image sensor exposure time for the frame of the period immediately before the mode conversion is defined as OLD_expotime and will be described later.

In addition, the table generation engine 114 obtains the OLD_expotime and then generates a table for the converted mode.

At this time, the table generation engine 114 generates a table such that the image sensor exposure time for the frame of the first period after the mode conversion is almost equal to the OLD_expotime.

The table generated by the table generation engine 114 includes an automatic exposure evaluation value item obtained by dividing the image sensor exposure time by the EXP_basetime and a digital amplification ratio item which is a brightness amplification ratio of the ISP. 100 pairs of automatic exposure estimates and digital amplification ratios are stored in the index.

In this case, each index is referred to as N (N: positive number within the range of 0 to 99), and the image sensor exposure time, automatic exposure evaluation value, and digital amplification ratio for each index are respectively exposure time [N] and automatic exposure evaluation value. [N] and the digital amplification ratio [N], the exposure time [N], the automatic exposure evaluation value [N] and the digital amplification ratio [N] are the following equations (1), (2) and (3). Obtained from

Here, EXP_maxtime is the maximum value of the image sensor exposure time, and the table generation engine 114 may determine the ratio of exposure time [N + 1] / exposure time [N], which is referred to as time factor. The timefactor may have a value between 0 and 1.

In addition, Gain_max is the maximum value of the digital amplification ratio, and Gain_min is the minimum value of the digital amplification ratio.

In addition, the table generation engine 114 sets the index at which the following equation (4) holds to No.

In addition, the table generation engine 114 may determine the ratio of the digital amplification ratio [N + 1] / digital amplification ratio [N], which is called a gain factor, and the gain factor is a value between 0 and 1. Can have

In Equations 1, 2, and 3, the values actually stored in the table are a pair of 100 automatic exposure evaluation values [N] and a digital amplification ratio [N] as described above.

In addition, the table completion register 115 is reset when the mode is changed, and when the table is generated, the table completion register 115 is set to inform that the table is updated.

 On the other hand, the distribution calculation unit 120 performs a function of calculating the distribution of the brightness component.

FIG. 3 is a diagram illustrating a storage area of the distribution calculator 120 according to the present invention. As shown in FIG. 3, when the minimum value of the brightness component of the pixel is 0 and the maximum value is 255, the frame is calculated. Among the total number of pixels constituting the image, the number of pixels with brightness components 0-15, the number of pixels with brightness components 16-31, ..., the number of pixels with brightness components 224-239, Find the number of pixels whose brightness components are 240-255, respectively.

Then, store the number of pixels with brightness components 0-15 in Bin0, store the number of pixels with brightness components 16-31 in Bin1, ......, the pixels with brightness components 224-239 Store the number of bins in Bin14, and store the number of pixels whose brightness components are 240 ~ 255 in Bin15.

At this time, if the brightness component distribution calculation operation of the distribution calculation unit 120 is completed, the distribution calculation unit completion register is set.

Meanwhile, the index selector 130 corrects a difference between a brightness average value and a target brightness value for a frame of a predetermined period currently input using the distribution chart calculated by the distribution chart calculator 120, and A function of selecting an index in which values necessary for adjusting the image sensor exposure time from the table is stored using the corrected value.

4 is a block diagram of the index selector 130 according to the present invention. As shown in FIG. 4, the index selector 130 according to the present invention includes an automatic exposure control unit 131 and an average level calculation unit ( 132, an error calculator 133, a cumulative error calculator 134, an index searcher 135, and a pause detector 136.

Here, the automatic exposure control unit 131 resets the distribution calculation unit completion register 137 and converts the average level when the distribution calculation unit completion register 137 is set when the table completion register 115 is set. Operate unit 132. However, if the distribution calculation unit completion register 137 is set while the table completion register 115 is reset, the automatic exposure control unit 131 performs only the task of resetting the distribution calculation unit completion register 137. .

In addition, the average level calculator 132 calculates a brightness average level value using the brightness distribution chart calculated by the distribution chart calculator 120.

The brightness average level value can be obtained through Equation 5, Equation 6, and Equation 7 described below.

In addition, the error calculator 133 calculates a brightness error that is a difference between the brightness average level value calculated in Equation 7 and a target brightness value.

The brightness error can be obtained through Equation 8 described below.

In addition, the cumulative error calculator 134 calculates a cumulative value for a brightness error of a frame inputted before.

The cumulative values Error_ACC and Final_Error can be obtained through Equations 9 and 10 described below.

In this case, Speed is a parameter that can adjust the tracking speed of the automatic exposure control, Error_ACC_old is Error_ACC of the frame image previously input, Bright_Error_old is the brightness error of the frame image previously input.

In addition, the index search unit 135 obtains a limit of a brightness error that can be corrected by using a cumulative value for the brightness error calculated in Equation 10. The limit of the brightness error is described in the following equation. Obtained from 11.

In addition, the index search unit 135 searches for an index in which an automatic exposure evaluation value and a digital amplification ratio are stored for a frame which is currently input by using the brightness error threshold obtained in Equation (11).

When Nc is an index in which an automatic exposure evaluation value and a digital amplification ratio are stored for a frame which is currently input, Nc can be obtained through Equation 12 described below.

In addition, the pause detector 136 performs a function of determining whether an ISP state for a frame of a predetermined period that is currently input is a pause.

That is, after the index search unit 135 searches for the index Nc, the automatic exposure control unit 131 determines whether the state of the current ISP is in the middle of the frame through the pause detector 136.

Therefore, during the pause period, the mode conversion control unit 111 sets the automatic exposure evaluation value [Nc] and the digital amplification ratio [Nc] to the image sensor and the ISP through the table generation engine 114, respectively. The setting of the automatic exposure evaluation value [Nc] in the image sensor may be performed through the sensor interface engine 117.

Also, the mode conversion control unit 111 stops outputting the image data for the mode immediately before the conversion through the table generation engine 114 and performs the image data output for the converted mode.

5 shows a flowchart of the automatic exposure control method according to the present invention, FIG. 6 shows a flowchart of the first step according to the present invention, FIG. 7 shows a flowchart of the third step according to the present invention, and FIG. 8 Shows a flowchart of the fourth step according to the present invention.

As shown in FIG. 5, the automatic exposure control method according to the present invention is a method of automatically adjusting the image sensor exposure time at one or more frames per resolution mode, and can be divided into four steps.

First, an index is formed, and a table is generated by storing values corresponding to a predetermined item in the index (S501).

Here, as shown in FIG. 6, the step S501 may be divided into 10 steps.

First, the mode transfer command received from the DSP is transferred (S501a).

Next, the completion register of the table for the mode immediately before conversion is reset (S501b).

Next, calculation of distribution of the brightness component for the mode immediately before conversion is stopped (S501c).

Then, image data output from the image sensor for the mode immediately before conversion is stopped (S501d).

Next, the resolution of the image sensor is converted (S501e).

Then, the resolution of the ISP is converted (S501f).

Subsequently, the basic unit of exposure time converted into the number of clocks by the image sensor is divided into clock frequencies and converted into time (S501g).

Next, the exposure time of the image sensor for the frame of the period immediately before the mode conversion is obtained using the converted exposure time basic unit (S501h).

Next, an index is formed, and a table is generated by storing values corresponding to a predetermined item in the index (S501i).

In this case, step S501i further includes generating a table such that the image sensor exposure time for the frame of the first period after the mode conversion is substantially the same as the image sensor exposure time for the frame of the period immediately before the mode conversion.

In addition, the step S501i, so that the table is composed of the automatic exposure evaluation value item divided by the exposure time basic unit of the image sensor exposure time and the digital amplification ratio item which is the brightness amplification ratio of the ISP, wherein each formed index 100 pairs of automatic exposure estimates and digital amplification ratios are stored.

Next, as a final step of the step S501, when the table is generated, set the completion register of the table for the converted mode (S501j).

On the other hand, after step S501, the distribution of the brightness component is calculated (S502).

Further, after step S502, the difference between the brightness average value and the target brightness value for the frame which is currently input is corrected using the distribution chart calculated in step S502, and the corrected value is used to correct the difference. In operation S503, an index in which values necessary for adjusting the image sensor exposure time are stored is selected from a table.

As illustrated in FIG. 7, the S503 stage may be divided into seven stages.

First, the completion register of the distribution chart calculation unit performing the step S502 is reset or the average register calculation unit that resets the completion register of the distribution chart calculating unit performing the step S502 and calculates the brightness average level value (S503a).

That is, if the distribution calculator complete register is set while the table completion register is set, the distribution calculator complete register is reset and the average level converting unit is operated. However, if the distribution calculator completion register is set while the table completion register is reset, only the task of resetting the distribution calculator completion register is performed.

Next, the brightness average level value is calculated using the brightness distribution chart calculated in step S502 (S503b).

Next, a brightness error that is a difference between the brightness average level value calculated in step S503b and the target brightness value is calculated (S503c).

Next, the cumulative value for the brightness error of the frame inputted before is calculated (S503d).

Then, the threshold of the brightness error that can be corrected is calculated using the cumulative value for the brightness error calculated in step S503d (S503e).

Next, the index in which the automatic exposure evaluation value and the digital amplification ratio are stored for the frame which is currently input is searched using the brightness error threshold calculated in step S503e (S503f).

Next, as a final step of the step S503, it is determined whether the ISP state for the frame of the current input period is at rest (S503g) and proceeds to the step S504 in the case of a rest period, and if it is not a rest period, feedback to the step S503g. do.

Meanwhile, after step S503, the exposure time of the image sensor is adjusted using the values stored in the index selected in step S503 (S504).

Here, as shown in FIG. 8, the step S504 may be divided into five steps.

First, the automatic exposure evaluation value stored in the searched index in step S503 is set in the image sensor (S504a).

Next, the digital amplification ratio stored in the index found in step S503 is set in the ISP (S504b).

Next, the image sensor exposure time is adjusted using the automatic exposure evaluation value and the digital amplification ratio set in the steps S504a and S504b (S504c).

Next, the distribution of brightness components for the mode converted according to the exposure time adjusted in step S504c is performed (S504d).

Next, as the last step of the step S504, image data output from the image sensor for the mode converted according to the exposure time adjusted in the step S504c is performed (S504e).

Preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications, and changes within the scope of the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It will be appreciated that such substitutions, changes, and the like should be considered to be within the scope of the following claims.

As described above, according to the automatic exposure control apparatus and method according to the present invention, since only the index of the table needs to be calculated as a table necessary for automatic exposure control is generated, the automatic exposure control time can be shortened. .

In addition, since only the index of the table needs to be calculated, an algorithm of the microprocessor may be easily implemented.

Claims (18)

In the automatic exposure control device that automatically adjusts the image sensor exposure time at least one frame per resolution mode, A table generation unit which forms an index and generates a table by storing values corresponding to a predetermined item in the index; A distribution calculator calculating a distribution of brightness components; Correcting the difference between the brightness average value and the target brightness value for a frame of a predetermined period currently input using the distribution chart calculated by the distribution calculator, and using the corrected value, the image sensor exposure time from the table. And an index selector for selecting an index in which values necessary to adjust the value are stored. The method of claim 3, wherein the table generation unit, A mode conversion control unit which receives a mode conversion command from a DSP to convert resolution modes of the ISP and the image sensor, and calculates a brightness component distribution diagram of the distribution calculator and controls image data output from the image sensor; A distribution controller which receives a command from the mode conversion controller and controls the distribution calculator; An exposure time basic unit calculator for dividing an exposure time basic unit converted into a number of clocks by the image sensor by a clock frequency and converting it into time; A table generation engine that obtains an image sensor exposure time for a frame of a period immediately before mode conversion by using the exposure time basic unit converted by the exposure time basic unit calculator, and generates a table for the converted mode; And And a table completion register which is reset when the mode is changed and is set when the table is generated. The method of claim 2, wherein the table generation engine, And generating a table such that the image sensor exposure time for the frame of the first period after the mode change is approximately equal to the image sensor exposure time for the frame of the period immediately before the mode change. The method of claim 2, wherein the table generation engine, And an automatic exposure evaluation value item obtained by dividing the exposure time of the image sensor by the basic unit of exposure time and a digital amplification ratio item which is a brightness amplification ratio of the ISP. The method of claim 4, wherein the table generation engine, And a table in which the automatic exposure evaluation value and the digital amplification ratio, which are composed of 100 pairs, are stored in each of the formed indexes. The method of claim 5, wherein the index selector, An average level calculator for calculating a brightness average level value using the brightness distribution calculated by the distribution calculator; An automatic exposure control unit which resets the completion register of the distribution calculator, or resets the distribution calculator completion register 136 and operates the average level calculator; An error calculator configured to calculate a brightness error that is a difference between the brightness average level value and a target brightness value; A cumulative error calculator configured to calculate a cumulative value for a brightness error of a frame inputted before; Obtain a limit of the brightness error that can be corrected by using the calculated cumulative error of the brightness error, and using the brightness error limit value is stored the automatic exposure evaluation value and the digital amplification ratio for the frame of the current input period An index search unit for searching an index; And Automatic exposure control device comprising a; idle state detection unit for determining whether the ISP state for the frame of the current period is a pause. The method of claim 6, wherein the mode conversion control unit, And when the ISP state is idle, setting the automatic exposure evaluation value stored in the index searched by the index search unit to the image sensor. The method of claim 6, wherein the mode conversion control unit, And when the ISP state is idle, setting the digital amplification ratio stored in the index searched by the index searching unit to the ISP. The method of claim 2, wherein the mode conversion control unit, Automatic exposure control device characterized in that to stop the output of the image data for the mode immediately before conversion and to proceed to output the image data for the converted mode. The method of claim 2, wherein the mode conversion control unit, And the distribution control unit controls the distribution calculator to stop calculating the distribution of the brightness components for the mode immediately before the conversion and to calculate the distribution of the brightness components for the converted mode. In the automatic exposure control method for automatically adjusting the image sensor exposure time at least one frame per resolution mode, A first step of forming an index and storing a value corresponding to a predetermined item in the index to generate a table; Calculating a distribution of brightness components; The difference between the brightness average value and the target brightness value for the frame which is currently input is corrected using the distribution chart calculated in the second step, and the image sensor exposure time is determined from the table using the corrected value. Selecting an index in which values necessary to adjust are stored; And And a fourth step of adjusting the exposure time of the image sensor by using values stored in the index selected in the third step. The method of claim 11, wherein the first step, A first step of delivering a mode conversion command received from the DSP; Resetting the completion register of the table for the mode immediately before conversion; Stopping the calculation of the distribution of the brightness components for the mode immediately before the conversion; 1-4 steps of stopping output of the image data from the image sensor for the mode immediately before conversion; 1-5 step of converting the resolution of the image sensor; First to sixth steps of converting the resolution of the ISP; A first to seventh steps of dividing an exposure time basic unit converted into a number of clocks by the image sensor by a clock frequency and converting the result into time; Calculating an image sensor exposure time for a frame of a period immediately before mode conversion by using the converted exposure time basic unit; And Forming an index and storing a value corresponding to a predetermined item in the index to generate a table; And When the table is generated, steps 1-10 of setting a completion register of the table for the converted mode; automatic exposure control method comprising a. The method of claim 12, wherein steps 1-9 include: And generating a table such that the image sensor exposure time for the frame of the first period after the mode change is substantially the same as the image sensor exposure time for the frame of the period immediately before the mode change. The method of claim 12, wherein the steps 1-9, And generating, by the table, an automatic exposure evaluation value item obtained by dividing the exposure time of the image sensor by the basic unit of exposure time and a digital amplification ratio item which is a brightness amplification ratio of the ISP. The method of claim 14, wherein the steps 1-9, And generating a table to store the automatic exposure evaluation value and the digital amplification ratio composed of 100 pairs in each of the formed indexes. The method of claim 15, wherein the third step, A step 3-1 of resetting the completion register of the distribution calculator calculating the second stage or operating the average level calculator calculating the brightness average level value by resetting the completion register of the distribution calculator calculating the second stage; A third step of calculating a brightness average level value using the brightness distribution calculated in the second step; Calculating a brightness error which is a difference between the brightness average level value and a target brightness value; Calculating a cumulative value for a brightness error of a frame inputted before; Calculating a threshold of brightness errors that can be corrected using the accumulated values of the calculated brightness errors; Searching for an index in which an automatic exposure evaluation value and a digital amplification ratio are stored for a frame which is currently input using the calculated brightness error threshold value; And And 3-7 determining whether an ISP state for a frame of a predetermined period that is currently input is at rest. The method of claim 16, wherein the steps 3-7, If the status of the ISP for the frame of the current input period is in the idle state, go to the fourth step, if not the automatic exposure control method, characterized in that fed back to the steps 3-7. The method of claim 16, wherein the fourth step, Step 4-1 of setting an automatic exposure evaluation value stored in the index found in steps 3-6 to the image sensor; Step 4-2 of setting the digital amplification ratio stored in the index searched in step 3-6 to the ISP; Adjusting the exposure time of the image sensor using the set automatic exposure evaluation value and the digital amplification ratio; A fourth step of performing a calculation of distribution of brightness components for the mode converted according to the adjusted exposure time; And And a fourth step of outputting image data from the image sensor for the mode converted according to the adjusted exposure time.

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