KR102244083B1 - Auto-focusing method of photographing apparatus - Google Patents

Abstract

Disclosed is an automatic focusing method of a photographing apparatus. This method includes steps (a) to (d). In step (a), priority is given to each of the partial regions in the image frame. In step (b), according to the priority, the maximum focus value of each of the partial regions is compared with the reference focus value. In step (c), from among the partial regions having a maximum focus value greater than the reference focus value, the nth (n is an integer greater than 0) partial region having the highest priority is found. In step (d), a focus position that generates a maximum focus value in the n-th partial region is applied as the final focus position.

Description

Automatic focusing method of photographing apparatus TECHNICAL FIELD

The present invention relates to an automatic focusing method of a photographing apparatus, and more particularly, to an automatic focusing method of a photographing apparatus that periodically searches for a final focus position while moving a focus lens or a photoelectric conversion unit.

A general photographing apparatus includes a focus lens, a photoelectric conversion unit, and a control unit. The photoelectric conversion unit is formed by a Charge Coupled Device (CCD) or Complementary Metal-Oxide-Semiconductor (CMOS).

In such an automatic focusing method of the photographing apparatus, for example, in the automatic focusing method of a surveillance camera, a position where the maximum focus value is generated is found while the distance between the focus lens and the photoelectric conversion unit is changed.

For example, in the case of a photographing apparatus equipped with a focus motor, a position for generating a maximum focus value is found while the focus lens moves while the photoelectric conversion unit is fixed.

Conversely, in the case of a photographing apparatus equipped with a motor of the photoelectric conversion unit, a position where the photoelectric conversion unit moves while the focus lens is fixed is found to generate the maximum focus value. As described above, in a photographing apparatus equipped with a motor of the photoelectric conversion unit, it may be used in various ways while the focus lens is replaced.

In the automatic focusing method of the photographing apparatus as described above, conventionally, automatic focusing has been performed only on a single partial region having the same center as the center of the image frame. However, when there is no image of an edge component in a single partial area, the found final focus position may not be an actual accurate focus position in most cases. For example, when an image on a smooth wall is located in a single partial area, the final focus position found is not an actual correct focus position in most cases.

In order to improve such a problem, the single partial area may be wider. In this case, since the area of the single partial region is widened, there is a high probability that the accuracy of focusing on the center is deteriorated. For example, when there is a difference in depth between a peripheral subject and a central subject, and the central subject has more edge components, the accuracy of focusing on the center deteriorates. Here, the depth refers to the distance between the photographing device and the subject.

Republic of Korea Patent Publication No. 2004-32378 (Applicant: Samsung Techwin Co., Ltd., title of invention: Automatic focusing method of camera using quadratic function).

Embodiments of the present invention perform optimal focusing when there is no edge component image in the center of an image frame, and when there is a difference in depth between a peripheral object and a central object Also, we would like to provide an automatic focusing method that makes it possible to perform optimal focusing.

According to an aspect of the present invention, an automatic focusing method of a photographing apparatus periodically searching for a final focus position while moving a focus lens or a photoelectric conversion unit includes steps (a) to (d).

In step (a), priority is given to each of the partial regions in the image frame.

In the step (b), according to the priority, the maximum focus value of each of the partial areas is compared with a reference focus value.

In step (c), from among the partial regions having a maximum focus value greater than the reference focus value, the nth (n is an integer greater than 0) partial region having the highest priority is found.

In the step (d), a focus position that generates a maximum focus value in the n-th partial region is applied as the final focus position.

According to the automatic focusing method of the photographing apparatus of the embodiments of the present invention, among the partial regions having a maximum focus value greater than the reference focus value, the n-th (n is an integer greater than 0) partial region having the highest priority. Is found. In addition, a focus position that generates a maximum focus value in the n-th partial region is applied as the final focus position.

Accordingly, when an image having an edge component does not exist in the center of the image frame, optimal focusing can be performed. For example, when the first partial region of the first priority does not have a maximum focus value greater than the reference focus value, focusing may be performed with the second partial region of the second priority as a main target. That is, focusing may be performed not targeting a central part without a subject, but targeting a peripheral part of the subject.

In addition, even when there is a difference in depth between a peripheral object and a central object, optimal focusing may be performed. For example, when both a first partial region of a first priority and a second partial region of a second priority have maximum focus values greater than the reference focus value, the first partial region of the first priority is assigned. Focusing may be performed on the target. That is, focusing may be performed not on the periphery but on the center.

1 is a diagram illustrating a first example of a photographing apparatus using an automatic focusing method according to embodiments of the present invention.
2 is a diagram showing a second example of a photographing apparatus using the automatic focusing method of the embodiments of the present invention.
3 is a flowchart showing an automatic focusing method of the first embodiment of the present invention performed by the digital signal processor (DSP) of FIG. 1 or 2.
4 is a diagram illustrating an example of partial regions set in an image frame according to a user's input in relation to step S301 of FIG. 3.
5 is a graph showing maximum focus values of three partial areas.
6 is a flowchart showing an automatic focusing method according to a second embodiment of the present invention performed by the digital signal processor (DSP) of FIG. 1 or 2.
7 is a flowchart showing an automatic focusing method according to a third embodiment of the present invention performed by the digital signal processor (DSP) of FIG. 1 or 2.
FIG. 8 is a diagram illustrating unit partition areas set for an image frame in connection with step S703 of FIG. 7.
9 is a diagram illustrating a line memory and a filter buffer used to perform step S703 of FIG. 7.

The following description and accompanying drawings are for understanding the operation according to the present invention, and parts that can be easily implemented by a person skilled in the art may be omitted.

In addition, the specification and drawings are not provided for the purpose of limiting the present invention, and the scope of the present invention should be determined by the claims. Terms used in the present specification should be interpreted as meanings and concepts consistent with the technical idea of the present invention so that the present invention can be most appropriately expressed.

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

1 shows a first example of a photographing apparatus 1 using the automatic focusing method of the embodiments of the present invention.

Referring to FIG. 1, a photographing apparatus 1 using the automatic focusing method of the embodiments of the present invention. For example, a surveillance camera includes an optical system (OPS), a photoelectric conversion unit (OEC), and a CDS-ADC as a digital signal generator. (Correlation Double Sampler and Analog-to-Digital Converter, 101), a digital signal processor (DSP, Digital Signal Processor, 107), a video-signal generator 108, and an interface unit 12.

An optical system OPS including a lens unit and a filter unit optically processes light from a subject. The lens unit of the optical system OPS includes a zoom lens and a focus lens.

The photoelectric conversion unit OEC of a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) converts light from the optical system OPS into an electrical analog signal. Here, the digital signal processor 107 controls the timing circuit 102 to control the operation of the photoelectric conversion unit OEC and the CDS-ADC 101.

The CDS-ADC 101 as a digital signal generator generates a digital video signal by processing an analog video signal from a photoelectric conversion section (OEC). More specifically, the CDS-ADC 101 processes the analog video signal from the photoelectric conversion unit OEC, removes the high-frequency noise, adjusts the amplitude, and converts it into digital video data. This digital image data is input to the digital signal processor 107.

The digital signal processor 107 converts the format of the digital video signal from the CDS-ADC 101 while controlling the operation of the optical system (OPS), the photoelectric conversion unit (OEC), and the CDS-ADC 101 as a digital signal generator. do. More specifically, the digital signal processor 107 processes a digital signal from the CDS-ADC element 101 to generate a digital image signal classified into a luminance and chroma signal.

The video-signal generator 108 converts the digital video signal from the digital signal processor 107 into a video signal Svid1 which is an analog video signal.

The digital signal processor 107 transmits the video signal Svid1 from the video-signal generator 108 to the host device while communicating with a host device (not shown) through the interface unit 12.

Meanwhile, the micro-computer 113 operated by the digital signal processor 107 as a control unit controls the driving unit 110 to drive the zoom motor Mz and the focus motor Mf. The zoom motor Mz drives the zoom lens, and the focus motor Mf drives the focus lens.

Further, the micro-computer 113 drives the lighting unit 115 under control from the digital signal processor 107.

The interface unit 12 rectifies the input AC voltage ACin to provide a DC voltage to each unit, and interfaces communication signals Sco between the digital signal processor 107 and an external host device.

In addition, the interface unit 12 interfaces the video signal Svid1 from the video-signal generator 108 and outputs the resulting video signal Svid through a BNC (Bayonet Neil-Concelman) receptacle. , Interfacing the communication signal Sse between the digital signal processor 107 and external sensors.

2 shows a second example of the photographing apparatus 1 using the automatic focusing method of the embodiments of the present invention. In FIG. 2, the same reference numerals as in FIG. 1 indicate objects of the same function. The only difference between the photographing apparatus 1 of FIG. 2 and the photographing apparatus 1 of FIG. 1 is as follows.

That is, in the photographing apparatus 1 of FIG. 1, the focus motor Mf is adopted instead of the motor of the photoelectric conversion unit OEC, but in the photographing apparatus 1 of FIG. 2, the photoelectric conversion unit OEC is used instead of the focus motor. Motor Ms is employed. The remaining components are as described in detail with reference to FIG. 1.

In the case of the photographing apparatus 1 employing the driving motor Ms of the photoelectric conversion unit OEC as described above, the maximum focus value is adjusted while the photoelectric conversion unit OEC moves while the focus lens in the optical system OPS is fixed. The location of the occurrence is found. Accordingly, as the focus lens is replaced, it can be used in various ways.

3 shows an automatic focusing method of the first embodiment of the present invention performed by the digital signal processor (DSP) 107 of FIG. 1 or 2.

4 shows an example of partial regions set in an image frame according to a user's input in relation to step S301 of FIG. 3. In FIG. 4, reference numeral 401 denotes an image frame. Reference numerals PA1 to PA9 denote partial regions set for an image frame.

5 shows maximum focus values of three partial areas. In FIG. 5, reference numeral DS denotes a focus position, and FV denotes a focus value, respectively.

The automatic focusing method according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

The digital signal processor (DSP, 107) gives priority to each of the partial regions PA1 to PA9 in the image frame 401 according to the user's input (step S301).

In setting the partial regions PA1 to PA9, the central positions of the partial regions PA1 to PA9 are the same as the center position C1 of the image frame 401, and the second partial region PA2 is the first It is wider than the partial area PA1. For example, the ninth partial area PA9 is wider than the eighth partial area PA8.

A first priority is given to the first partial area PA1 having an outline closest to the center of the image frame 401. A final ninth priority is given to the ninth partial area PA9 having an outline farthest from the center of the image frame 401.

Next, the digital signal processor (DSP, 107) compares the maximum focus values FV1 to FV3 of each of the partial areas with a reference focus value according to the priority (step S303).

Further, the digital signal processor (DSP, 107) determines whether there is a partial area having a maximum focus value larger than the reference focus value (step S305).

When there is a partial area having a maximum focus value greater than the reference focus value, the following steps S307a and S309a are performed.

In step S307a, the digital signal processor (DSP, 107) finds the nth (n is an integer greater than 0) partial region having the highest priority among partial regions having a maximum focus value greater than the reference focus value.

In step S309a, the digital signal processor (DSP, 107) applies the focus position for generating the maximum focus value in the n-th partial region as the final focus position.

For example, when there are first to third partial regions PA1 to PA3 having a maximum focus value FV1 to FV3 greater than the reference focus value, the maximum focus value FV1 in the first partial region PA1 The focus position DS1 for generating is applied as the final focus position.

Accordingly, even when there is a difference in depth between a peripheral object and a central object, optimal focusing can be performed. That is, focusing may be performed not on the periphery but on the center.

Also, for example, when only the first to third partial regions PA1 to PA3 are set, and only the third partial regions PA1 to PA3 have a maximum focus value FV3 greater than the reference focus value, the first The focus position DS3 for generating the maximum focus value FV3 in the three partial area PA3 is applied as the final focus position.

Accordingly, optimal focusing can be performed when an image having an edge component does not exist in the center of the image frame. That is, focusing may be performed not targeting a central part without a subject, but targeting a peripheral part of the subject.

On the other hand, when there is no partial area having a maximum focus value greater than the reference focus value, the following steps S307b and S309b are performed.

In step S307b, the digital signal processor (DSP, 107) finds the m-th (m is an integer greater than 0) partial region having the largest maximum focus value among the maximum focus values of the partial regions.

For example, when only the first to third partial regions PA1 to PA3 are set and there is no partial region having a maximum focus value greater than the reference focus value, the maximum focus values of the partial regions PA1 to PA3 The third partial area PA3 having the largest maximum focus value among (FV1 to FV3) is found.

In step S309b, the digital signal processor (DSP, 107) applies the focus position for generating the maximum focus value in the m-th partial region as the final focus position.

For example, when only the first to third partial regions PA1 to PA3 are set and there is no partial region having a maximum focus value greater than the reference focus value, the maximum focus value ( The focus position DS3 that generates FV3) is applied as the final focus position.

The above steps S303 to S309b are repeatedly performed until the end signal is generated (step S311) and each time a setting period elapses (step S313).

6 shows an automatic focusing method according to a second embodiment of the present invention performed by the digital signal processor (DSP) 107 of FIG. 1 or 2. The second embodiment of FIG. 6 corresponds to a case in which only the first and second partial regions (PA1 and PA2 of FIG. 4) are set. The automatic focusing method of the second embodiment of FIG. 6 will be described with reference to FIGS. 1, 2 and 4 to 6 as follows.

The digital signal processor (DSP, 107) gives priority to the first partial area PA1 and the second partial area PA2 in the image frame 401 according to the user's input (step S601).

In setting the partial regions PA1 and PA2, the center positions of the partial regions PA1 and PA2 are the same as the center position C1 of the image frame 401, and the second partial region PA2 is the first It is wider than the partial area PA1.

A first priority is given to the first partial area PA1 having an outline close to the center of the image frame 401. A second priority is given to the second partial area PA2 having an outline far from the center of the image frame 401.

Next, the digital signal processor (DSP, 107) obtains the maximum focus value FV1 of the first partial area PA1 having the first priority (step S603).

Next, the digital signal processor DSP 107 determines whether or not the maximum focus value FV1 of the first partial area PA1 is higher than the reference focus value FVref (step S605).

When the maximum focus value FV1 of the first partial area PA1 is higher than the reference focus value FVref, the digital signal processor DSP 107 generates the maximum focus value FV1 of the first partial area PA1. The resulting focus position DS1 is applied as the final focus position (step S607).

Accordingly, even when there is a difference in depth between a peripheral object and a central object, optimal focusing can be performed. That is, focusing may be performed not on the periphery but on the center.

If the maximum focus value FV1 of the first partial area PA1 is not higher than the reference focus value FVref, the digital signal processor DSP 107 is The focus value FV3 is obtained (step S609).

Next, the digital signal processor DSP 107 determines whether or not the maximum focus value FV2 of the second partial area PA2 is higher than the reference focus value FVref (step S611).

When the maximum focus value FV2 of the second partial area PA2 is higher than the reference focus value FVref, the digital signal processor DSP 107 generates the maximum focus value FV2 of the second partial area PA2. The resulting focus position DS2 is applied as the final focus position (step S613a).

Accordingly, optimal focusing can be performed when an image having an edge component does not exist in the center of the image frame. That is, focusing may be performed not targeting a central part without a subject, but targeting a peripheral part of the subject.

If the maximum focus value FV2 of the second partial area PA2 is not higher than the reference focus value FVref, the digital signal processor DSP 107 is the largest among the maximum focus values FV1 and FV2 of the partial areas. A partial region having a focus value is found, and a focus position for generating the maximum focus value in the found partial region is applied as the final focus position (step S613b).

The above steps S603 to S613b are repeatedly performed until the end signal is generated (step S615) and each time a setting period elapses (step S617).

FIG. 7 shows an automatic focusing method according to a third embodiment of the present invention performed by the digital signal processor (DSP) 107 of FIG. 1 or 2.

_{FIG. 8 shows unit partition areas DB 11} to DBpq set for the image frame 801 in relation to step S703 of FIG. 7.

The third embodiment of FIG. 7 corresponds to a case in which only the first and second partial regions (PA1 and PA2 of FIG. 4) are set. In addition, the third embodiment of FIG. 7 corresponds to a case in which the second embodiment of FIG. 6 is more specific. Referring to FIGS. 1, 2, 4, 5, and 7, 8, the automatic focusing method of the third embodiment of FIG. 7 will be described as follows.

The digital signal processor (DSP, 107) gives a first priority to the first partial region PA1 in the image frames 401 and 801, and gives a second priority to the second partial region PA2 ( Step S701).

Next, the digital signal processor (DSP, 107) obtains focus values of the _{unit partition areas DB 11} to DBpq with respect to the frame data obtained at each position of the focus lens or the photoelectric conversion unit OEC (step S703).

Further, the digital signal processor (DSP, 107) uses the focus values _{of the unit partition areas DB 11} to DBpq at each position DS of the focus lens or the photoelectric conversion unit OEC, Average focus values of the first partial area PA1 at each position DS of the photoelectric conversion unit OEC are obtained (step S705).

Next, the digital signal processor (DSP, 107) calculates the largest average focus value among the average focus values of the first partial area PA1 at each position DS of the focus lens or the photoelectric conversion unit OEC. It is set as the maximum focus value FV1 of one partial area PA1 (step S707).

Further, the digital signal processor DSP 107 determines whether or not the maximum focus value FV1 of the first partial area PA1 is higher than the reference focus value FVref (step S709).

When the maximum focus value FV1 of the first partial area PA1 is higher than the reference focus value FVref, the focus position DS1 generating the maximum focus value FV1 of the first partial area PA1 is the final focus position. Is applied as (step S711).

Accordingly, even when there is a difference in depth between a peripheral object and a central object, optimal focusing can be performed. That is, focusing may be performed not on the periphery but on the center.

When the maximum focus value FV1 of the first partial area PA1 is not higher than the reference focus value FVref, the digital signal processor DSP 107 is configured to each position DS of the focus lens or the photoelectric conversion unit OEC. ), the average focus values of the second partial area PA2 at each position of the focus lens or the photoelectric conversion unit OEC are obtained using the focus values of the unit partition areas DB _{11 to DBpq (} Step S713).

Also, the digital signal processor (DSP, 107) determines the largest average focus value among the average focus values of the second partial area PA2 at each position DS of the focus lens or the photoelectric conversion unit. ) Is set as the maximum focus value FV2 (step S715).

In calculating the average focus values of the second partial area PA2 at each position DS of the focus lens or the photoelectric conversion unit OEC in step S713, the maximum of the second partial area PA2 in the previous period is calculated. Calculation can be started from the focus position that generated the focus value. In addition, several focus positions before and after the focus position that generated the maximum focus value of the second partial area PA2 in the previous period without calculating all the focus positions of the second partial area PA2. Can only be calculated for This is because there is a high probability of generating the maximum focus value again around the focus position that generated the maximum focus value in the previous period.

Accordingly, since the time taken to perform the steps S713 and S715 is greatly reduced, the focusing operation can be performed more quickly. Of course, this fast method of finding the maximum focus value can be used for all other partial areas as well. That is, it can also be used in step S303 of FIG. 3.

Next, the digital signal processor DSP 107 determines whether or not the maximum focus value FV2 of the second partial area PA2 is higher than the reference focus value FVref (step S717).

When the maximum focus value FV2 of the second partial area PA2 is higher than the reference focus value FVref, the digital signal processor DSP 107 generates the maximum focus value FV2 of the second partial area PA2. The resulting focus position DS2 is applied as the final focus position (step S719a).

Accordingly, optimal focusing can be performed when an image having an edge component does not exist in the center of the image frame. That is, focusing may be performed not targeting a central part without a subject, but targeting a peripheral part of the subject.

If the maximum focus value FV2 of the second partial area PA2 is not higher than the reference focus value FVref, the digital signal processor DSP 107 is the largest among the maximum focus values FV1 and FV2 of the partial areas. A partial region having a focus value is found, and a focus position for generating the maximum focus value in the found partial region is applied as the final focus position (step S719b).

The steps S703 to S719b are repeatedly performed until the end signal is generated (step S721) and each time a setting period elapses (step S723).

9 shows a line memory 901 and a filter buffer 902 used to perform step S703 of FIG. 7.

Referring to FIGS. 8 and 9, in performing step S703 of FIG. 7 _{, focus values of the unit partition regions DB 11} to DBpq are obtained by a single high-pass filter.

The capacity of the filter buffer 902 used by the high-pass filter and the image data capacity M*Y of each of the _{unit partition regions DB 11 to DBpq are the same.} That is, focus values of image data corresponding to M pixels in the horizontal direction and Y pixels in the vertical direction are obtained by one operation of the high-pass filter.

In the present embodiment, the number of horizontal lines of the line memory 901 that provides image data to the filter buffer 902 may be implemented by one less than the number of horizontal lines of the filter buffer 902. To this end, the image data of the final horizontal line Y of the filter buffer 901 is input to the filter buffer 902 without passing through the line memory 901. That is, while all the serial input data Din is stored in the line memory 901, _{the image data of the unit partition regions DBp 1} to DBpq is moved to the filter buffer 902, and the final horizontal line ( The video data of Y) is input to the filter buffer 902 without passing through the line memory 901.

As described above, according to the automatic focusing method of the photographing apparatus of the embodiments of the present invention, among partial regions having a maximum focus value greater than a reference focus value, the nth having the highest priority (n is an integer greater than 0). ) The partial area is found. In addition, a focus position that generates a maximum focus value in the n-th partial region is applied as the final focus position.

Accordingly, when an image having an edge component does not exist in the center of the image frame, optimal focusing can be performed. For example, when the first partial region of the first priority does not have a maximum focus value greater than the reference focus value, focusing may be performed with the second partial region of the second priority as a main target. That is, focusing may be performed not targeting a central part without a subject, but targeting a peripheral part of the subject.

In addition, even when there is a difference in depth between a peripheral object and a central object, optimal focusing may be performed. For example, when both the first partial region of the first priority and the second partial region of the second priority have maximum focus values greater than the reference focus value, the first partial region of the first priority is the main target. As a result, focusing can be performed. That is, focusing may be performed not on the periphery but on the center.

So far, we have looked at the center of the preferred embodiment for the present invention. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention.

Therefore, the disclosed embodiments should be considered from an explanatory point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the above description, and the invention claimed by the claims and the inventions equivalent to the claimed invention should be construed as being included in the invention.

There is a possibility that it may be used auxiliary in the manual focusing process of the photographing device.

1: photographing device, 12: interface unit,
OPS: optical system, OEC: photoelectric conversion unit,
101: digital signal generator, 102: timing circuit,
107: control unit, 108: video-signal generator,
110: driving unit, 113: micro-computer,
115: lighting unit, Mf: focus motor,
Mz: zoom motor, Ms: photoelectric conversion unit motor,
401: image frame, PA1 to PA9: partial regions,
DS: focus position, FV: focus value,
801: image frame, DB ₁₁ to DBpq: unit partition regions,
901: line memory, 902: buffer for filter.

Claims (6)

In the automatic focusing method of a photographing apparatus for periodically finding a final focus position in consideration of priority of partial regions of an image frame having a maximum focus value,
(a) giving priority to each of the partial regions in an image frame;
(b) comparing the maximum focus value of each of the partial areas with a reference focus value according to the priority;
(c) from among the partial regions having a maximum focus value greater than the reference focus value, finding the nth (n is an integer greater than 0) partial region having the highest priority; And
(d) applying a focus position for generating a maximum focus value in the n-th partial region as the final focus position. The method of claim 1,
In the step (b), when at least one partial area having a maximum focus value greater than the reference focus value does not exist,
In the step (c), the m-th (m is an integer greater than 0) partial region having the largest maximum focus value among the maximum focus values of the partial regions is found,
In the step (d), a focus position that generates a maximum focus value in the m-th partial region is applied as the final focus position. In the automatic focusing method of a photographing apparatus for periodically finding a final focus position while moving a focus lens or a photoelectric conversion unit,
(a) giving priority to at least a first partial region and a second partial region in an image frame;
(b) obtaining a maximum focus value of the first partial region having a first priority;
(c) if the maximum focus value of the first partial region is higher than the reference focus value, a focus position generating the maximum focus value of the first partial region is applied as a final focus position;
(d) if the maximum focus value of the first partial region is not higher than the reference focus value, obtaining the maximum focus value of the second partial region having a second priority; And
(e) if the maximum focus value of the second partial region is higher than the reference focus value, applying a focus position generating the maximum focus value of the second partial region as a final focus position; and
In step (a),
The center positions of the first and second partial regions are the same as the center positions of the image frame,
Wherein the second partial region is wider than the first partial region. delete In the automatic focusing method of a photographing apparatus for periodically finding a final focus position while moving a focus lens or a photoelectric conversion unit,
(a) Priority is given to at least the first and second sub-regions in an image frame, but a first priority is given to the first sub-region, and a second priority is given to the second sub-region. box;
(b) obtaining focus values of unit partition areas for frame data obtained at each position of the focus lens or photoelectric conversion unit;
(c) obtaining average focus values of the first partial region at each position of the focus lens or photoelectric conversion unit by using focus values of the unit partition regions at each position of the focus lens or photoelectric conversion unit;
(d) setting the largest average focus value of the average focus values of the first partial region at each position of the focus lens or the photoelectric conversion unit as the maximum focus value of the first partial region;
(e) if the maximum focus value of the first partial region is higher than the reference focus value, a focus position generating the maximum focus value of the first partial region is applied as a final focus position;
(f) If the maximum focus value of the first partial area is not higher than the reference focus value, the focus lens or the photoelectric conversion unit is Obtaining average focus values of the second partial area at each position;
(g) setting the largest average focus value of the average focus values of the second partial region at each position of the focus lens or the photoelectric conversion unit as the maximum focus value of the second partial region; And
(h) when the maximum focus value of the second partial region is higher than the reference focus value, a focus position that generates the maximum focus value of the second partial region is applied as a final focus position. The method of claim 5, wherein in step (b),
Focus values of the unit partition regions are obtained by a single high-pass filter,
The capacity of the filter buffer used by the high-pass filter and the image data capacity of each of the unit partition regions are the same,
The number of horizontal lines of the line memory providing image data to the filter buffer is one less than the number of horizontal lines of the filter buffer,
The image data of the final horizontal line of the filter buffer is input to the filter buffer without passing through the line memory.

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