KR20100099011A - Method and apparatus for processing auto-focusing information, and digital photographing apparatus using thereof - Google Patents

Abstract

PURPOSE: An automatic focusing process method for preventing defocus, an apparatus thereof, and a digital photographing device using the same are provided to perform compensation in case a digital photographing apparatus fails an automatic focusing operation. CONSTITUTION: An automatic focusing process is performed using an automatic focusing window(406). An automatic focusing return value of a subject is compared with an automatic focusing return value of the background according to the auto focusing performance(408). If the two values are similar, the automatic focusing is compensated based on the automatic focusing return value(414).

Description

Method and apparatus for auto focusing, and digital photographing apparatus using the same {Method and apparatus for processing auto-focusing information, and digital photographing apparatus using liter}

The present invention relates to auto focusing, and more particularly, to an auto focusing processing method and apparatus, and a digital photographing apparatus using the same.

Most digital cameras have a feature called AutoFocus that focuses on the subject you want to shoot to get a good picture.

Autofocus is the function of an optical system (camera) that automatically focuses on a specific object (subject). Most compact digital cameras use TTL contrast detection. The compact digital camera does not have a separate auto focus sensor, and focuses by analyzing the contrast of the image obtained through the CCD / CMOS image sensor.

In general, an auto focus (AF) method of adjusting the focus of a photographing lens of a digital camera, the image of the subject is photoelectrically converted by an imaging element such as a CCD to generate an image signal, and from the image signal of a predetermined AF area in the captured image. It is known to calculate an AF evaluation value that is a contrast value of an image by extracting a high frequency component and to detect the focusing position of a photographing lens based on the AF evaluation value.

In this method, the AF evaluation value is calculated at each position (focusing position) of the focus lens while moving the focus lens in the optical axis direction, and the position at which the AF evaluation value is maximized is detected as the focusing position. In particular, the function of the autofocus of the face center is to solve the problem that the person who is trying to photograph is blurred because the subject is not suitable for the person to be photographed and the subject is focused on another subject such as a landscape.

However, when AF is completed through the above-described AF method and AF is performed, a photographing is often performed when the photographer focuses on the background instead of focusing on the intended subject. In such a case, when the edge component of the background is stronger than the edge component of the center subject, that is, the person to be photographed, the out of focus appears at a high frequency. In this situation, the AF value of the center AF window and the AF value of the surrounding AF window, that is, the area including the background image, are almost coincident with each other.

The prior art for preventing such a focal point used a method such as coloring on the edge of a specific threshold range, and superimposed it on photographic image data, or enlarging an image of a specific region and displaying it to the user. However, these methods are not suitable for processing live view images displayed in real time due to excessive calculation amount in edge detection and coloring process, and there is a problem of systematically creating a load.

The present invention has been made to solve the above-described problems of the prior art, and provides a subject AF window and a background AF window, respectively, when the edge component of the background is stronger than the edge component of the central subject, and considers respective AF values. It is an object of the present invention to provide an auto focusing processing method and apparatus capable of performing an accurate focusing operation and allowing a photographing by correcting the auto focusing failure.

Another object is to provide a digital photographing apparatus using the same.

In order to solve the above technical problem, the auto focusing processing method according to an embodiment of the present invention comprises the steps of providing each of the AF window for the subject and the background; Performing auto focusing on each of the AF window for the subject and the AF window for the background; Comparing the auto focusing result of the subject with the auto focusing result of the background according to the auto focusing; And correcting auto focusing based on the auto focusing result of the subject when the auto focusing result of the subject is similar to the auto focusing result of the background.

Preferably, the auto focusing method further includes displaying whether auto focusing succeeds according to the comparison result,

When the auto focusing result value of the subject is similar to the auto focusing result value of the background, the auto focusing function may be displayed.

Preferably, the correcting step is characterized by correcting the auto focusing by moving the auto focusing position according to the AF value of the subject by one unit step.

Preferably, the unit is based on a coverzone arbitrarily set according to the specification of the focus lens.

Preferably, the AF window providing step, wherein each window for the subject and the background provides a different AF window according to at least one or more of the composition of the shot, the size of the subject, the size of the point of focus, the method of shooting. do.

Preferably, the size and position of the AF window is adjustable.

According to another aspect of the present invention, there is provided an auto focusing processing apparatus, including: an AF window providing unit providing respective AF windows for a subject and a background; An auto focusing unit which performs auto focusing on each of the AF window for the subject and the AF window for the background; A controller configured to compare an auto focusing result of the subject and an autofocusing result of the background according to the auto focusing; And an auto focusing correction unit configured to correct auto focusing based on the auto focusing result of the subject when the auto focusing result of the subject and the background auto focusing result are similar.

Preferably, the control unit controls to display whether or not auto focusing succeeds according to the comparison result, and when the auto focusing result value of the subject is similar to the auto focusing result value of the background, to indicate that the auto focusing has failed. It is characterized by controlling.

Preferably, the auto focusing corrector corrects auto focusing by moving the auto focusing position by one unit step according to the auto focusing result of the subject.

Preferably, the AF window providing unit may provide different AF windows according to at least one of the composition of the subject, the size of the subject, the size of the focusing point, and the photographing method for each window of the subject and the background. .

In order to solve the another technical problem, a recording medium recording a program for executing the auto focusing method according to another embodiment of the present invention on a computer.

In order to achieve the above another technical problem, a digital photographing apparatus including an auto focusing processing apparatus according to another embodiment of the present invention is included.

An auto focusing method according to an embodiment of the present invention provides an AF window for a subject and a background, performs auto focusing on each of an AF window for a subject and an AF window for a background, and performs auto focusing. By comparing whether the AF result value of the subject and the AF result value of the background are similar, auto focusing can be accurately performed, and when auto focusing fails, correcting it can prevent misfocus and shoot.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts may be omitted so as not to distract from the gist of the present invention.

In addition, terms and words used in the following description and claims should not be construed to be limited to ordinary or dictionary meanings, but are to be construed in a manner consistent with the technical idea of the present invention As well as the concept.

1 is a block diagram of a digital camera according to an embodiment of the digital photographing apparatus of the present invention. 2, which will be described with reference to FIG. 1, is a block diagram illustrating a digital signal processor of the digital camera.

As shown in FIG. 1, the digital camera 100 includes an optical unit 10, an optical driver 11, an imaging device 15, an imaging device controller 16, an operation unit 20, and a program storage unit 30. And a buffer storage unit 40, a data storage unit 50, a display control unit 60, a data driver 61, a scan driver 63, a display unit 65, and a digital signal processor DSP.

The optical unit 10 receives an optical signal from a subject and provides it to the imaging device 13. The optical unit 10 may include at least one lens, such as a zoom lens for controlling the view angle to be narrowed or widened according to a focal length, and a focus lens for focusing a subject. In addition, the optical unit 10 may further include an aperture for adjusting the amount of light.

The optical driver 11 adjusts the position of the lens, opening and closing of the iris, and the like. You can focus by shifting the position of the lens. In addition, the amount of light may be adjusted by adjusting the opening and closing of the iris. The optical driver 11 may control the optical unit 10 according to a control signal automatically generated by an image signal input in real time or a control signal manually input by a user's manipulation.

The optical signal transmitted through the optical unit 10 reaches the light receiving surface of the imaging element 15 to form an image of the subject. The imaging device 15 may use a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor Image Sensor (CIS) that converts an optical signal into an electrical signal. Such an image pickup device 15 may be controlled by the image pickup device controller 16. The imaging device controller 16 may also control the imaging device 15 according to a control signal automatically generated by an image signal input in real time or a control signal manually input by a user's operation.

The operation unit 20 is a place that can input a control signal from the outside such as a user. The operation unit 20 is a shutter-release button for inputting a shutter-release signal for taking a picture by exposing the imaging device 15 to light for a predetermined time, a power button for supplying power, and an angle of view according to the input. There are a wide-angle zoom button and a tele-zoom button to widen or narrow the angle of view, and various function buttons such as selecting a text input or shooting mode, a playback mode, selecting a white balance setting function, and selecting an exposure setting function. The operation unit 20 may have the form of various buttons as described above, but is not limited thereto, and may be implemented in any form that a user can input, such as a keyboard, a touch pad, a touch screen, a remote controller, and the like. In addition, in a preferred embodiment of the present invention, the user can select the AF window for the subject and the AF window for the background, respectively, and can manipulate the size and shape of the AF window in various ways.

In addition, the digital camera 100 may include a program storage unit 30 for storing a program such as an operating system or an application system for driving the digital camera, and a buffer storage unit for temporarily storing data or result data necessary for performing an operation ( 40), a data storage unit 50 for storing a variety of information required for the program, including an image file containing a video signal.

In addition, the digital camera 100 is a display control unit 60 for controlling to display its operation state or the image information photographed by the digital camera 100, a data driver input from the display control unit 60 to transfer the display data And a display unit 65 for displaying a predetermined image according to signals input from the data driver 61 and the scan driver 63. The display unit 65 may be formed of a liquid crystal display panel (LCD), an organic light emitting display panel (OLED), an electrophoretic display panel (EPD), and the like. In addition, in a preferred embodiment of the present invention, the display unit 65 displays the respective AF window for the subject and the background on the live view screen. In addition, whether or not the auto focusing is successful according to the auto focusing result is displayed to the user.

The digital camera 100 includes a DSP 70 for processing the input image signal and controlling the components according to the input signal or the external input signal.

The digital signal processing unit 70 will be described with reference to FIG. 2 together.

Referring to FIG. 2, the DSP 70 includes a controller 71, an image signal processor 72, an AF window provider 73, an auto focusing unit 74, and an auto focusing corrector 75. The digital signal processor 70 used in the following description should be understood as having the same meaning as the auto focusing apparatus used in the claims.

The controller 71 controls the overall operation of the digital signal processor 70. The controller 71 compares whether the auto focusing result value of the subject output from the auto focusing unit 74 is similar to the auto focusing result value of the background, and controls whether or not the auto focusing success is displayed to the user according to the comparison result. For example, if the image contains a lot of edge components in the background, the auto focusing result of the subject, that is, the auto focusing result of the AF window of the subject, the AF position corresponding to the peak of the AF curve and the auto focusing result of the background, That is, if the AF position corresponding to the peak of the AF curve is similar as a result of performing the auto focusing on the AF window in the background, in this case, the error is prevented by notifying the user that auto focusing has failed.

In addition, the controller 71 controls the auto focusing corrector 75 to correct the failed auto focusing when the auto focusing result of the subject and the background auto focusing result are similar. Here, the auto focusing correction corrects the AF by moving the AF position by a unit step based on the auto focusing result value of the subject. Preferably, the unit may be an amount of movement of the AF position that can be arbitrarily set or a cover zone determined according to the specification of the focus lens.

In addition, the control unit 71 displays various AF window frames output from the AF window providing unit 73 to the user. When the AF window for the displayed subject and background is selected by the user, information on the selected AF window area is provided to the auto focusing unit 74.

The image signal processor 72 converts an image signal input from the image pickup device 15 into a digital signal, and performs gamma correction and color filter array interpolation to convert the image signal according to the human vision. Image signal processing such as color matrix, color correction, color enhancement, and the like. In addition, when the function is set, the image signal processor 72 may perform an auto white balance or auto exposure algorithm. In addition, the size of the image data is adjusted using a scaler and compressed to form an image file of a predetermined format. Conversely, image files can be extracted. The image signal processing unit 72 may perform the above image signal processing on the image signal input in real time in the live-view mode before the picture taking and the image signal input by the shutter-release signal. In this case, different video signal processing may be performed on each of the video signals.

The AF window providing unit 73 provides respective AF windows for the subject and the background so that the user can select them. The AF window may be provided differently according to a photographing composition which the user wants to capture, for example, a landscape composition or a portrait composition. In addition, it can be provided in various ways depending on the size of the subject, the size of the focusing point, the shooting method. Here, the AF window will be described with reference to FIGS. 3A to 3D.

3A-3D, various AF window frames are shown.

3A illustrates a horizontal composition, and illustrates an AF window frame when a central subject is to be photographed. The AF window 310 for the subject and the AF window 320 for the background are shown. 3B is a vertical composition, and shows the AF window frame when the central subject is to be photographed. Similarly, the AF window 310 for the subject and the AF window 320 for the background are shown. 3C is a horizontal composition, and shows an AF window frame when the size of the range point is to be taken small. Similarly, the AF window 310 for the subject and the AF window 320 for the background are shown. 3D is a horizontal composition, and shows an AF window frame when self-photographing is to be performed. Similarly, the AF window 310 for the subject and the AF window 320 for the background are shown.

The various AF window frames described with reference to FIGS. 3A to 3D are exemplary and not limited thereto, and may provide various AF window frames. In addition, the size and shape of the AF window on the subject or background can be adjusted manually by the user.

The auto focusing unit 74 performs AF processing on the AF window area for the subject and the background selected by the user among the AF windows for the subject and the background provided by the AF window providing unit 73. In general, the AF processing may perform AF processing by a contrast detection method or AF processing by pan focus. For example, the AF processing by the contrast detection method moves the focus lens to the lens position where the contrast value of the AF area determined to perform AF is the highest. That is, the focus lens is moved, the contrast of the CCD is converted into an electrical signal, the waveform is analyzed, and the focus lens is aligned to the lens position where the high frequency component is the largest, and the focus is adjusted. Here, the auto focusing unit 74 outputs to the controller 71 an AF value that is an AF value for the AF window region for the subject and an AF value for an AF window region for the background. .

The auto focusing corrector 75 compares the auto focusing result value of the subject output from the auto focusing performing unit 74 with the background auto focusing result value, and if so, performs auto focusing correction. Here, the correction of the auto focusing is performed based on the auto focusing result value of the subject. In other words, the failure of auto focusing is a case where the subject is not in focus and the background part (the part containing a lot of edge components) in the subject window is in focus, thereby shifting the AF position by one unit step. Here, the degree of the unit step may be arbitrarily determined or based on a coverzone arbitrarily set according to the specification of the focus lens. The cover zone means a range of focal lengths set according to the focus lens for each digital photographing apparatus.

Referring to FIG. 5A, a center AF window 500 of a subject, another AF window 510 of a subject, and an AF window 520 of a background are respectively shown.

Referring to FIG. 5B, the AF performance result curve 500 for the center AF window 500 is illustrated, and the AF performance result curve 510 for the other AF window 510 of the subject and the AF window 520 in the background are shown. The AF performance curves for the curves are respectively shown. In FIG. 5B, the horizontal axis may be an AF position, and the vertical axis may be an AF value, for example, a contrast value for a corresponding window. Therefore, the AF positions of the AF curve peaks of the center AF window 500 of the subject and the AF window 520 of the background are similarly shown as 500. In this case, instead of focusing on the person in the center subject, it may be determined that the back background in the area of the AF window 500, that is, the part in which the AF value is high due to the large number of edge components is in focus. Therefore, AF determines that it has failed, and performs AF correction. Here, AF is corrected by moving the AF position by one unit step from the AF curve 500 of the central subject. In addition, referring to the AF curve 510 of another AF window of the near subject, it can be seen that the AF position is maximized at the 510 portion. Therefore, the focal point can be prevented by moving the AF position of the AF window curve 500 of the center subject in the 510 direction. Here, the movement amount is moved by one unit step as described above.

4 is a flowchart illustrating an auto focusing processing method according to another embodiment of the present invention.

Referring to FIG. 4, in step 400, an AF window is set, which provides an AF window for a subject and a background. In step 402, the AF window set in the live view screen is displayed. In step 404, it is determined whether there is a user input for the AF window for the displayed subject and the background. That is, it is determined whether there is a user's selection for the displayed AF window. If the user selects the AF window for the specific subject and the AF window for the specific background or the entire background, in step 406, AF for the AF window for the subject and the background selected by the user is performed. In operation 408, it is determined whether the AF result value of the subject AF window is similar to the AF value of the background window. Here, the criteria for determining similarity may be arbitrarily determined.

As a result of the determination in step 408, if AF succeeds (step 412), that is, when the AF result value for the subject and the AF result value for the background are not similar, the process proceeds to steps 416 and 418 to record and record.

As a result of the determination in step 408, if the AF fails (step 410), that is, if the AF result value for the subject and the AF result value for the background are similar, the process proceeds to step 414 to correct the AF based on the AF result value of the subject. . Here, AF correction is as described above.

Optionally, the user may be informed whether the AF succeeds or fails.

Although the above embodiments have been described with reference to a digital camera as an example of a digital photographing apparatus to which the present invention can be applied, the present invention is not limited thereto. Those skilled in the art will understand that the present invention can be applied to camera phones, personal digital assistants (PDAs), and portable multimedia players (PMPs).

Meanwhile, the present invention can be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which may also be implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers skilled in the art to which the present invention belongs.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will understand that the present invention can be embodied in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown not in the above description but in the claims, and all differences within the scope should be construed as being included in the present invention.

1 is a schematic block diagram of a digital photographing apparatus 100 according to an exemplary embodiment.

2 is a detailed block diagram of the digital signal processor 70 shown in FIG. 1.

3A to 3D are diagrams for describing a subject AF window and a background AF window according to another embodiment of the present invention.

4 is a flowchart illustrating an auto focusing processing method according to another embodiment of the present invention.

5 is a diagram for describing an auto focusing correction method according to another exemplary embodiment.

<Explanation of symbols for the main parts of the drawings>

71: control unit 72: image signal processing unit

73: AF window provider 74: AF execution unit

75: AF compensator

Claims (12)

Providing respective AF windows for a subject and a background; Performing auto focusing on each of the AF window for the subject and the AF window for the background; Comparing the auto focusing result of the subject with the auto focusing result of the background according to the auto focusing; And And correcting auto focusing based on the autofocusing result of the subject when the autofocusing result of the subject is similar to the autofocusing result of the background. The method of claim 1, And displaying whether auto focusing succeeds according to the comparison result. And if the auto focusing result of the subject is similar to the auto focusing result of the background, indicating that the auto focusing has failed. The method of claim 1, The correction step, And autofocusing by correcting the autofocusing position according to the autofocusing result of the subject by one unit step. The method of claim 3, wherein The unit is An auto focusing processing method characterized by based on a cover zone arbitrarily set according to a specification of a focus lens. The method of claim 2, The AF window providing step, And the respective windows for the subject and the background provide different AF windows according to at least one of a photographing composition, a size of the subject, a size of a focusing point, and a photographing method. The method of claim 1, The size and position of the AF window, An auto focusing processing method characterized by being adjustable. A recording medium having recorded thereon a program for executing a method according to any one of claims 1 to 6 on a computer. An AF window providing unit for providing respective AF windows for the subject and the background; An auto focusing unit which performs auto focusing on each of the AF window for the subject and the AF window for the background; A controller configured to compare an auto focusing result of the subject and an autofocusing result of the background according to the auto focusing; And And an auto focusing correction unit configured to correct auto focusing based on the auto focusing result of the subject when the auto focusing result of the subject is similar to the auto focusing result of the background. The method of claim 8, The control unit, Control to display whether auto focusing succeeds according to the comparison result, and if the auto focusing result value of the subject is similar to the auto focusing result value of the background, controlling to display that the auto focusing has failed. Focusing processing device. The method of claim 8, The auto focusing correction unit, And autofocusing by correcting the autofocusing position by one unit step according to the autofocusing result of the subject. The method of claim 10, The AF window providing unit, And the respective windows for the subject and the background provide different AF windows according to at least one of a photographing composition, a size of the subject, a size of a focusing point, and a photographing method. A digital photographing apparatus comprising the auto focusing processing apparatus according to any one of claims 8 to 11.

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