KR20090112396A - Digital photographing apparatus, and auto-focusing method of the same - Google Patents

Abstract

PURPOSE: A digital photographing device and an auto focusing method thereof are provided to perform the accurate auto focusing although the hand of a photographer is shaken or a subject is moved. CONSTITUTION: A digital photographing device comprises the first focusing unit which photographs the first image(P1) by focusing a subject(S) with the first focus distance(L1), the second focusing unit which photographs the second image(P2) by focusing the subject with the second focus distance(L2), and image analyzing unit which compares auto focusing levels of the focus areas of first and second images, and an image selection unit which acquires one of the first and second images having higher auto focusing level.

Description

Digital photographing apparatus, and auto-focusing method of the same

The present invention relates to a digital photographing apparatus and an auto focusing method thereof, and more particularly to a digital photographing apparatus and an auto focusing method capable of obtaining a precise focusing effect selectable by a photographer.

In general, the digital photographing apparatus includes any device that processes an image of a digital camera, a personal digital assistant (PDA), a phone camera, a PC camera, or uses an image recognition sensor.

When the user presses the shutter release button in the digital photographing apparatus, the image received through the image pickup device may be image processed by the digital signal processor, and may be compressed and stored as an image file. In addition, the digital photographing apparatus may display an image received through an image pickup device or an image stored in a storage medium on a display device such as a liquid crystal display (LCD).

Such a digital photographing apparatus automatically adjusts the focus by an auto focusing function to take a clear picture.

On the other hand, when taking a picture using a digital photographing apparatus, when focus is achieved by performing auto focusing, the photograph actually taken may not be the photograph of the focus desired by the photographer because of the camera shake or subject movement.

In order to solve this problem, according to Korean Patent Laid-Open Publication No. 2006-0129498, after shifting the position of a focus lens at a predetermined interval and storing all of the images at the corresponding position as a series, an image of the optimum focus is acquired. The method has been proposed.

However, since the above method determines the focus quality of the image by analyzing the entire image area in analyzing the image stored in the memory, the performance of the image processor processing each image should be high. In addition, since the focus lens acquires images while moving from the first start position to the end position at regular intervals, there are a large number of images that are unnecessarily acquired, and in order to increase the focus accuracy, the focus lens moves from the start position to the end position. It is necessary to subdivide the stages of memory, which further increases the capacity of the memory.

The present invention has been made to solve various problems including the above problems, and an object of the present invention is to provide a digital photographing apparatus and an auto focusing method capable of simply increasing the accuracy of auto focusing.

In order to achieve the above object, the present invention provides a first focusing unit for capturing a first image of the subject by focusing on a first focus distance with respect to a subject, and the first focus distance with respect to the subject. A second focusing unit configured to capture a second image of the subject by focusing at a second focus distance spaced from a predetermined distance from a predetermined distance, and an auto focusing level of a focus area of the first image and a focus area of the second image A digital photographing apparatus includes an image analyzing unit for comparing the and an image selecting unit for acquiring an image having a high auto focusing level among the first image and the second image.

The present invention may further include an interval setting unit for setting an interval from the first focus distance to the second focus distance and a storage unit for storing the set interval.

The present invention may further include a number setting unit for setting the number of sheets of the second image having different second focus distances and a storage unit for storing the set number of sheets.

The present invention further includes a mode setting unit for allowing a photographer to set a mode and a mode-specific adjusting unit for adjusting the interval or the number of sheets according to the mode set by the photographer, and the storage unit controls the interval or the number of sheets for each of the set modes. You can save it.

The present invention also provides a first focusing step of capturing a first image of the subject by focusing at a first focus distance with respect to a subject, and for the subject, in advance from the first focus distance. A second focusing step of capturing a second image of the subject by focusing at a second focus distance spaced by a set distance, and comparing an autofocusing level of a focus area of the first image with a focus area of the second image; And acquiring an image having a high auto focusing level among the first image and the second image.

The second image may be composed of a plurality of images having different second focus distances with respect to the subject.

The second focus distance may be located in front of the subject toward the subject from the first focus distance and rearward from the subject.

The first image and the second image may be a whole image of the subject, and the focus area may be a partial area of the first image and the second image.

According to the present invention as described above, even if there is camera shake or subject movement, accurate auto focusing can be achieved.

In addition, since the auto focusing quality is compared again with the photograph obtained by moving the focus lens again in the auto focusing state, the focusing quality can be further improved.

Since the images are compared with the focusing area of the acquired images, there is no need to increase the performance of the image processor or increase the capacity of the memory.

In addition, since the setting of the second focus distance can be arbitrarily set by the photographer, it may be more useful for a DSLR camera requiring various photographing effects.

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

1 is a block diagram illustrating a digital photographing apparatus according to an embodiment of the present invention. The overall operation of the digital photographing apparatus is integrated by the CPU 100. In addition, the digital photographing apparatus includes an operation unit 80 including a key for generating an electrical signal from a user. The electrical signal from the operation unit 80 is transmitted to the CPU 100 so that the CPU 100 can control the digital photographing apparatus according to the electrical signal.

The operation unit 80 includes a function selection input unit for setting various modes, a shutter release button, and the like. The shutter release button cooperates with the aperture 20 to properly expose the subject so that an image is recorded on the imaging device 30. The shutter release button includes a button unit provided to be operable by an actual user and a button control unit for controlling an operation of the button to transmit an electrical signal to the CPU 100.

In the photographing mode, as the electrical signal from the user is applied to the CPU 100, the CPU 100 detects the signal and controls the lens driver 11, the aperture driver 21, and the imaging device controller 31. Accordingly, the position of the lens unit 10, the opening degree of the diaphragm 20, the sensitivity of the imaging device 30, and the like are respectively controlled.

The lens unit 10 may include a zoom lens 11, a focus lens 12, and a lens driver 13.

The zoom lens 11 and the focus lens 12 are provided at positions where their optical axes coincide with the vertical lines extending from the substantially center of the light receiving surface of the imaging device 30. The focus lens 12 is provided to be movable in a straight line back and forth on the optical axis, and changes the focus position of the image formed on the light receiving surface of the imaging element 30 in accordance with the movement position. The movement position of the focus lens 12 is controlled by the CPU 100 via the lens driver 13. In addition, the lens unit 10 may further include various lenses according to the type of the digital photographing apparatus and the selection of the photographer.

The lens unit 10 may include, for example, an infrared cut filter for cutting infrared light of incident light, a shutter blade for shielding incident light, and the like, and the lens driver 13 may drive the zoom lens 11. A zoom lens driver and a shutter driver for driving the shutter blades may also be provided.

The lens unit 10 as described above may be exchanged by the user.

The image pickup device 30 accumulates the amount of light input through the zoom lens 11 and the focus lens 12, and vertically captures the image captured by the zoom lens 11 and the focus lens 12 according to the accumulated light amount. Output according to the synchronization signal. Image acquisition of the photographing apparatus is performed by the image pickup device 30 that converts the light reflected from the subject into an electrical signal. In order to obtain a color image using the image pickup device 30, a color filter is required, and a filter (not shown) called a color filter array (CFA) is mostly adopted. CFA has a structure arranged regularly by passing only one color light per pixel, and has various shapes according to the arrangement structure.

The imaging device 30 generates data regarding an image from the input light, and the analog / digital converter 40 converts analog data output from the imaging device 30 into digital data. Of course, the analog / digital converter 40 may not be necessary depending on the characteristics of the imaging device 30. On the other hand, since the data about the image is generated from the light entering through the lens unit 10 in the aperture 20 and the image pickup device 30, at least one component of the aperture 20 and the image pickup device 30 is imaged. It may also be referred to as a data acquisition unit. Of course, at least one component of the diaphragm 20, the image pickup device 30, the analog / digital converter 40, and the digital signal processor 50 may be referred to as an image data acquisition unit. to be.

Data from the image pickup device 30 may be input to the digital signal processing unit 50 via the memory 60, or may be input to the digital signal processing unit 50 without passing through the memory 60. It may also be input to 100. The memory 60 is a concept including a ROM or a RAM. The digital signal processor 50 may perform digital signal processing such as gamma correction and white balance adjustment, if necessary.

The image data output from the digital signal processor 50 is transmitted to the display controller 81 through the memory 60 or directly. The display controller 81 controls the display 80 to display an image on the display 80. The image data output from the digital signal processing unit 50 is inputted through the memory 60 or directly to the storage / reading control unit 71. The storage / reading control unit 71 automatically or according to a signal from a user. The image data is stored in the recording medium 70. Of course, the storage / reading control unit 71 reads data related to the image from the image file stored in the recording medium 70 and inputs the data regarding the image to the display control unit 81 through the memory 60 or through another path. 80 may be displayed. The recording medium 70 may be detachable or may be permanently mounted to the digital photographing apparatus.

Data from light incident on the image pickup device 30 through the lens unit 10 may be image data or temporary image data. In this case, the temporary image data means data about a temporary image for display on the display unit 80 of the digital photographing apparatus according to a signal from a user, not data about a large size image for storing on the recording medium 70. do. Of course, in the digital photographing apparatus, a live view image similar to a moving image may be displayed on the display unit 80 using data from light incident on the image pickup device before shooting. It may mean one frame image according to the signal of.

Meanwhile, the auto focusing of the present invention uses the bracketing technique of the digital photographing apparatus, and as shown in FIG. 2, the first image P1 of the subject is focused by focusing the subject S at a first focus distance L1. ), And focus another second focus distance L2 spaced apart from the first focus distance L1 by a predetermined distance to take another second image P2 of the subject S. Among them, the auto focusing level is obtained by obtaining an image with a high level. To this end, the present invention further includes a first focusing unit 110, a second focusing unit 120, an image analyzing unit 130, and an image selecting unit 140 as shown in FIG. 3 for the auto focusing. do. 3 is a block diagram for explaining a part of the digital photographing apparatus of FIG. 1. For example, the components shown in FIG. 3 may be part of the CPU 100 shown in FIG. 1. Of course, although not shown in Figure 1, the components shown in Figure 3 may be a separate independent component that is not part of the CPU.

As shown in FIG. 2, the first focusing unit 110 generates a subject S by a half-button signal generated by the photographer pressing the shutter release button of the operation unit 80 to one end of the half-button state. The first image P1 of the subject S is photographed by focusing on the first focus distance L1. The photographed first image P1 may be sent to the image analyzer 130.

In this case, when the photographer presses the shutter release button of the operation unit 80 to one end of the half button state, the first focusing unit 110 moves the focus lens 12 along the optical axis while moving the plurality of focus images. It receives an input and obtains a focus value at each focus position.

The focus value may be obtained by detecting edges in each focus image and adding them together. The image having the largest amount of edges may be the image having the largest focus value. At this time, the position of the focus lens 12 becomes the first focus position L1.

As shown in FIG. 2, the second focusing unit 120 generates a subject S by a full button signal generated as the photographer presses the shutter release button of the operation unit 80 to the second stage of the full button state. The focus lens 12 is focused at a second focus distance L2 spaced apart from the first focus distance L1 by a predetermined distance to take a second image P2 of the subject S. FIG. As described above, the first image P1 may also be photographed according to the full button signal. That is, after the first focus position L1 is determined by the half button signal, the first image P1 and the second image P2 may be photographed according to the full button signal. The photographed second image P2 may also be sent to the image analyzer 130.

The second image P2 may include a plurality of images having different second focus distances L2 with respect to the subject S.

According to an exemplary embodiment of the present invention shown in FIG. 2, the second focus distance L2 is equal to the first distance D1 in a direction away from the subject S from the first focus distance L1. The rear second focus distance L21 and the front second focus distance L22 spaced apart by the second distance D2 in the direction toward the subject S from the first focus distance L1 are spaced apart. have. Accordingly, the rear second image P21 and the front second image P22 may be acquired, respectively.

In the above embodiment, it is shown that one second focus distance L2 is formed at the front and the rear with respect to the first focus distance L1, but the present invention is not necessarily limited thereto, and the second focus distance is shown. The L2 may be positioned only at either one of the front and the rear of the first focus distance L1, and the number of the second images P2 acquired according to this may be variously changed.

The captured first image P1 and the second image P2 are compared by the image analyzer 130. In this case, the first image P1 and the second image P2 captured as described above may be the entire image of the subject S, and the image analyzer 130 may be configured to display the first image P1. ) And the auto focusing level of each focus area, which is a partial area of the second image P2, can be compared. At this time, the comparison of the auto focusing level is performed by comparing the contrast in the focusing area of the image detected using contrast AF (Auto Focusing) and / or passive AF, that is, the highest contrast is detected. A large image is one whose autofocusing level is high.

Thus, such image analysis does not require a large amount of information processing.

The image analyzer 130 may be provided in a memory or may be provided in the CPU 100.

When the optimal image of the first image P1 and the second image P2 is identified through the image analyzer 130, the image selector 140 may display the first image P1 and the second image ( One of P2) is selected. In this case, as described above, if the second image P2 includes a plurality of images, one of the first image P1 and the second image P2 is selected.

Meanwhile, according to another preferred embodiment of the present invention, as shown in FIG. 4, the interval setting unit 121 and the storage unit 122 may be further included.

The interval setting unit 121 sets the first interval D1 and the second interval D2, which are intervals between the first focus distance L1 and the second focus distance L2. The set interval is stored in the storage 122. The interval setting unit 121 and the storage unit 122 may be included in the second focusing unit 120, but are not necessarily limited thereto, and may be connected to the second focusing unit 120.

The photographer may preset the interval between the first focus distance L1 and the second focus distance L2 through the interval setting unit 121. In this case, as shown in FIG. 2, the interval may be set such that the first interval D1 and the second interval D2 are provided at the same time, or only one of these intervals may be set. That is, the photographer may allow the area in which the second focus distance L2 is set through the interval setting unit 121 to be positioned both front and rear with respect to the first focus distance L1, and may be positioned only in one side of the front or the rear. It can also be located.

If there is no photographer setting, the same interval can be applied in all cases. For example, when there is no setting of the photographer, two second focusing distances L2 spaced apart at +/- 3 Cm intervals based on the first focusing distance L1 may be applied as in the general bracket photographing.

Accordingly, when the second focusing unit 120 performs the aforementioned second focusing, the second focusing distance 120 may be spaced apart from the first focusing distance L1 by using the information about the interval stored in the storage 122. Focus on L2) and take a second image P2.

The present invention may also further include a number setting unit 123, as shown in FIG.

The number setting unit 123 sets the number of shots of the second image P2 focused and photographed at the second focus distance L2. The set number of sheets is stored in the storage unit 122. The number setting unit 123 and the storage unit 122 may be included in the second focusing unit 120, but are not limited thereto and may be connected to the second focusing unit 120.

The photographer may preset the number of shots of the second image P2 focused at the second focus distance L2 through the number setting unit 123. In the case of the embodiment according to FIG. 2, two sheets of the rear second image P21 and the front second image P22 are set as the second image P2. The photographer can set the number of shots as four, and as described above, when the second focus distance L2 is located only on either one of the front and the rear with respect to the first focus distance L1, Can also be set.

 If there is no photographer setting, the same interval can be applied in all cases. For example, as shown in FIG. 2, one rear second image P21 and one front second image P22 may be set.

Therefore, when the second focusing unit 120 performs the above-described second focusing, the second image P2 at the second focus distance L2 by the number of sheets set through the information about the number of sheets stored in the storage unit 122. ).

In the embodiment according to FIG. 5, the number setting unit 123 is provided at the same time as the interval setting unit 121, but the present disclosure is not limited thereto, and the number setting unit 123 may be provided alone.

6 illustrates another embodiment of the present invention, which further includes a mode setting unit 124 and a mode adjusting unit 125.

The mode setting unit 124 allows to set a mode, for example, a portrait mode, a background mode, and the like. Such a mode may use a mode set by another function of the digital photographing apparatus or may be a mode newly set by the photographer. The set mode is stored in the storage 122.

The mode-specific adjusting unit 125 adjusts the aforementioned intervals and / or the number of sheets according to the mode set by the photographer. The interval and the number of sheets set for each mode are stored in the storage unit 122.

For example, after the photographer sets the modes to the portrait photography mode and the background photography mode, the photographer sets the above-described intervals and the number of sheets for each mode. The set data is stored in the storage 122.

The intervals and the number of sheets for each mode may be preset to default before being set by the photographer.

For example, in the portrait mode, since the focus of the subject is the eye of the face, the second focus distance L2 is set within ± 3 cm back and forth around the first focus distance L1.

In the case of the background mode, in most cases, the person is photographed in the landscape, so the second focus distance L2 is set within ± 50 cm to 1.5 m in front and rear with respect to the first focus distance L1.

Next, the auto focusing method of the digital photographing apparatus of the present invention will be described in detail with reference to the above-described drawings and FIG. 7.

First, in the second focusing setting step S1, the photographer may determine whether to perform general auto focusing shooting or two-step auto focusing shooting according to the present invention.

If the photographer selects normal auto focusing shooting (No), the photographer may acquire the first image through the first focusing described above (S2), digitize it (S11), and store and display the same (S12).

That is, according to the half button signal generated when the photographer presses the shutter release button of the operation unit 80 to one end of the half button state, the first focusing unit 110 is connected to the subject S as shown in FIG. 2. The first image P1 of the subject S is photographed by focusing on the first focus distance L1. The first image P1 may be captured by a half button signal, but is captured by a full button signal after the half button signal.

The first image P1 may be selected by the image selector 140, but is not limited thereto and may be immediately displayed on the display unit 90 via the memory 60.

When the photographer selects the second focusing (Yes), the photographer may select whether to set the mode (S3). If the photographer does not select the mode setting (No), after the first focusing (S7), the second focusing is performed according to the interval and the number of sheets stored in the digital photographing apparatus (S8).

When the photographer selects the mode setting (Yes), first, the interval and the number of sheets are sequentially set and stored for each mode (S4 and S5). After that, after selecting the stored mode (S6), to take a picture.

After the first focusing and the second focusing (S7, S8), the auto focusing level of the focus areas of the first image P1 and the second image P2 is compared (S9), and an optimal image is selected ( S10).

The selected image is stored and displayed (S12) via digitization (S11).

A program for executing the method of controlling the digital photographing apparatus according to the above-described embodiments and modified examples thereof in the digital photographing apparatus may be stored in a recording medium. Here, the recording medium may be a recording medium 70 as shown in FIG. 1, a memory 60 as shown in FIG. 1, or may be a separate recording medium. The recording medium may include various storage media such as, for example, a ROM, a RAM, a floppy disk, a hard disk, a CD-ROM, a DVD (Digital Versatile Disc), a flash memory, and the like. Of course, for example, it may be the CPU 100 in FIG. 1 or a part thereof.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a block diagram illustrating a digital photographing apparatus according to an embodiment of the present invention.

2 is a conceptual diagram schematically showing a photographing state by a digital photographing apparatus according to the present invention.

3 is a block diagram illustrating some components of a digital photographing apparatus according to an exemplary embodiment of the present invention.

4 is a block diagram illustrating a part of a configuration of a digital photographing apparatus according to another exemplary embodiment of the present invention.

FIG. 5 is a block diagram illustrating some components of a digital photographing apparatus according to another exemplary embodiment.

6 is a block diagram illustrating a part of a configuration of a digital photographing apparatus according to another embodiment of the present invention.

7 is a flowchart for describing a method of controlling a digital photographing apparatus according to another exemplary embodiment of the present invention.

Claims (8)

A first focusing unit configured to capture a first image of the subject by focusing a first focus distance on the subject; A second focusing unit configured to capture a second image of the subject by focusing on the subject at a second focus distance spaced apart from the first focus distance by a predetermined distance; An image analyzer which compares an auto focusing level of a focus area of the first image with a focus area of the second image; And And an image selector for acquiring an image having a higher auto focusing level among the first image and the second image. The method of claim 1, An interval setting unit for setting an interval from the first focus distance to the second focus distance; And And a storage unit for storing the set interval. The method of claim 1, A number setting unit for setting the number of second images having different second focus distances; And And a storage unit for storing the set number of sheets. The method according to claim 2 or 3, A mode setting unit that allows the photographer to set a mode; And Further comprising a mode-specific adjusting unit for adjusting the interval or the number of copies according to the mode set by the photographer, And the storage unit stores the interval or the number of sheets for each of the set modes. A first focusing step of capturing a first image of the subject by focusing a first focus distance on the subject; A second focusing step of capturing a second image of the subject by focusing on the subject at a second focus distance spaced apart from the first focus distance by a predetermined distance; Comparing the auto focusing level of the focus area of the first image with the focus area of the second image; And And acquiring an image having a higher auto focusing level among the first image and the second image. The method of claim 5, And the second image comprises a plurality of images having different second focus distances to the subject. The method of claim 5, And the second focusing distance is located in front of the first focusing distance from the first focusing distance and rearward away from the subject. The method of claim 5, The first image and the second image is a whole image of the subject, And wherein the focus area is a partial area of the first image and the second image.

Images