KR20110007438A - Auto-focusing controller and the auto-focusing control method which uses this - Google Patents

Abstract

PURPOSE: An auto-focusing controller and an auto-focusing control method using the same are provided to divide a photographed image into groups to assign a weight value through a maximum focus value, a focus distance difference between groups, and a focus distance average value, thereby easily controlling a focus of a subject. CONSTITUTION: An image processing unit processes a photographed image. A CPU(Central Processing Unit)(140) divides the processed image into a plurality of windows. The CPU classifies a preset number of windows into one group. A focus value calculating unit(142) calculates a maximum focus value of a group. A focus distance calculating unit(143) calculates a focus distance of the group. A focus distance average calculating unit(144) calculates the average of the calculated focus distance.

Description

Auto-focusing controller and the auto-focusing control method which uses this}

The present invention relates to an automatic focusing apparatus and an automatic focusing method using the same, and more particularly, dividing the captured image into a plurality of groups having the same weight, and the maximum focus value of each group, the difference in the focal length between each group and the focal length The present invention relates to an auto focusing device for allocating weights using an average value and an auto focusing method using the same.

In general, portable terminals such as mobile phones and PDAs are used not only for simple phone functions but also for multi-convergence of music, movies, TV, and games, and one of the things leading the development of such multi-convergence. As a camera module capable of taking images as the most representative.

The camera module is changing from the existing 300,000 pixels to the center of the high pixel and gradually miniaturized, and is being changed to implement various additional functions such as auto focusing (AF) and optical zoom. Research is underway on the implementation of.

In general, the operation method of the auto focus camera module is calculated through the edges passed through the high pass filter after signal processing the image acquired through the CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor in the mobile phone. The extracted focus value is transferred to the central processing unit. The central processor issues a command to the lens driver by determining the moving direction and distance of the focus lens based on the calculated focus value, thereby automatically focusing as the lens moves.

In this case, the central processor uses an autofocus algorithm that assigns a weight to the center window on the assumption that the subject is located at the center. This is because most of the users are interested in the center of the screen.

However, this auto focusing operation is guaranteed on the assumption that all subjects are located in the center, but there is a problem in that accurate focusing performance cannot be expected when the subjects are located in the edge window or variously distributed.

Accordingly, the present invention is to solve the disadvantages and problems of the auto focusing apparatus and the auto focusing method using the same, and divides the captured image into a plurality of groups having the same weight and the maximum focus value, each It is an object of the present invention to provide an autofocus control device and an autofocus control method using the same, by easily assigning a weight using a focal length difference and a focal length average value between groups, according to the environment and distribution of a subject.

The present invention for achieving the above object is provided with a lens for imaging the image of the subject; An image processing stage for signal processing an image picked up from the imaging stage; And a central processing unit for dividing the signal processed by the image processing unit into a plurality of windows, classifying a predetermined number of windows among the plurality of windows into one group, and assigning a weight to each other. A focus value calculator configured to calculate a maximum focus value of each group; A focal length average value calculating unit for calculating a focal length average value of the maximum focal values of the group; And a focal length calculator for calculating a focal length of each group.

The central processing unit may further include a window controller for dividing the image into at least nine windows and classifying the image into at least five groups.

In this case, the image may include a central window positioned in the central region and a plurality of peripheral windows of a shape surrounding the central region.

The focus focal length average value calculator may calculate an average value of the maximum focus values calculated from the focus value calculator.

And a driving stage for driving the lens of the imaging stage by the control signal of the central processing stage.

The display may further include a display unit configured to display an image processed by the image processor.

According to an aspect of the present invention, there is provided a signal processing method of photographing an image and classifying the signal-processed image into one group by calculating a maximum focus value and a focal length of each group; Calculating a focal length average value of each group; Extracting positions of short-range groups by analyzing the maximum focal value and focal length; Comparing a focal length difference between the short range groups with a mean focal length of the group; And assigning a weight to a window belonging to a short-range group corresponding to the comparison result.

Further, in the step of calculating the average focal length of each group. The focal length average value may be calculated by obtaining an average of the maximum focal values of the groups.

The method may further include determining whether the short range group is located in a central area after extracting the location of the short range group.

Further, in the step of comparing the focal length difference between the groups with the focal length of the short-range group, when the short-range group is located in the center region, the difference in the focal length between each group is smaller than the average of the focal length between the groups It can be compared in some cases.

In addition, in the step of comparing the focal length difference between each group and the focal length of the near group, when the near group is located in the peripheral region, the difference in the focal length of the group is smaller than the average of the focal length between the groups Can be compared.

The method may further include transferring the lens to a position corresponding to the window to which the weight is assigned, after the assigning the weight to the window belonging to the short-range group corresponding to the comparison result.

As described above, the automatic focusing apparatus and the automatic focusing method using the same according to the present invention divides the captured image into a plurality of groups having the same weight, the maximum focus value of each group, the difference in focal length between each group and the focus By assigning weights using the distance average value, the focus can be easily adjusted according to the environment and distribution of the subject.

Matters relating to the operational effects including the technical configuration of the auto focusing apparatus and the auto focusing method using the same according to the present invention will be clearly understood by the following detailed description with reference to the drawings in which preferred embodiments of the present invention are shown. .

With reference to Figures 1 and 4 will be described in detail with respect to the auto focusing apparatus and the method for adjusting the auto focus using the same according to an embodiment of the present invention.

Auto focus

1 and 2 is a configuration diagram for an auto focusing apparatus according to an embodiment of the present invention.

1 and 2, the auto focusing apparatus 100 according to an exemplary embodiment of the present invention includes an image capturing terminal 110 for capturing an image of a subject, and image processing for signal processing the captured image. A stage 120 includes a display stage 130 for displaying the signal processed image, a central processing stage 140, and a driving stage 150.

The imaging stage 110 includes an image sensor which is a high imaging device and a lens for changing the focus and moved in the up and down directions, and is connected to the image processing stage 120 and the driving stage 150. The imaging stage 110 moves the lens in the vertical direction by the driving stage 150 to adjust the focus of the image to inject light of the subject into the image sensor.

Preferably, the image sensor is a CCD sensor or a CMOS sensor. The image sensor converts the incident light into an electrical signal and displays the incident light to the image processing terminal 120.

The image processing stage 120 is connected to the imaging stage 110, the display 130, and the central processing stage 140, and performs automatic white balance, automatic exposure, and gamma correction on the image captured by the imaging stage 100. By performing signal processing such as to convert the image of the image displayed through the display unit 130 according to the human vision.

As shown in FIG. 2, the central processing unit 120 includes a window controller 141, a focus value calculator 142, a focal length average value calculator 143, and a focal length calculator 144.

The central processing unit 120 controls the image processed by the image processing unit 120 and transmits the control signal to the driving unit 150.

The window controller 141 divides the image into a plurality of windows, and classifies a predetermined number of windows among the plurality of windows into one group. At this time, the weight of each group is initialized to the same value.

The image is composed of a central window located in the central region and a plurality of peripheral windows shaped around the central region. The present invention divides the image into at least nine windows and divides them into at least five groups. This will be described later in detail.

The focus value calculator 142 calculates a maximum focus value for each group classified by the window controller 141. In this case, when the focus is well achieved, the focus value is high, and when the focus is not well, the focus value is low.

The focal length calculator 143 calculates a focal length of each group classified by the window controller 141, and the focal length average value calculator 144 is calculated by the focal length calculator 143. The average value of the focal length of each group is calculated. In this case, if the average value is large, the subject is located at a short distance, and if the average value is small, the subject is at a far distance.

In this way, the central processing unit 140 receives the signal-processed image from the image processing unit 120 and divides it into a plurality of groups having the same weight, and the maximum focus value, focal length difference and focus for each group. By assigning a weight to the group using a distance average value, the focus can be easily adjusted according to the environment and distribution of the subject. In this case, the auto focus adjusting method to which the weight is assigned by the central processing unit 140 will be described later.

The driving stage 150 is an actuator, and the actuator may be configured as a voice coil method using a Lorentz force such as a magnet or a coil by using a leaf spring or a wire leaf spring, and a piezo method using a piezoelectric element. Can be. The driving stage 150 drives the lens of the imaging stage 110 according to the control signal detected from the central processing stage 140.

How to adjust auto focus

3 and 4 are configuration diagrams for an auto focus adjusting method according to an embodiment of the present invention.

3 is a flowchart illustrating an auto focus adjusting method according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram showing a plurality of windows employed in an embodiment of the present invention.

Referring to FIGS. 3 and 4, the auto focus adjusting method according to the embodiment of the present invention is a method for auto focusing by using the auto focus adjusting device 100 having the same configuration as that of FIGS. 1 and 2 described above. The overlapping description will be omitted below.

First, an image of a subject is captured and signal processed. This is accomplished by the imaging stage 110 and the image processing stage 120. Next, the signal processed image is divided into a plurality of windows, and a predetermined number of windows among the plurality of windows are classified into one group to calculate a maximum focus value of each group and a focal length of each group. S100)

Next, an average value of the focal lengths of each group is calculated. (S110) The average focal length is an average value of the focal lengths. This is done by the central processing unit 140.

The image is composed of a central window positioned in the central region and a plurality of peripheral windows shaped around the central region. The present invention can be divided into nine windows as shown in FIG. 4 and classified into at least five groups. In the drawings, w denotes a window, and G denotes a group consisting of a plurality of windows.

Next, the location of the short range group is extracted by analyzing the maximum focus value and the focal length (S120). In this case, the short range group is a group in which the maximum focus value is high and the focal length is calculated to the minimum. Next, it is determined whether the extracted short range group is located in the central area (S130).

If the short range group is located in the central region, that is, when the short range group is G1, G3, the difference between the focal lengths between the groups and the average focal length of the group are compared (S133). If the difference is smaller than the average focal length value, a weight is assigned to the center window (S140). That is, a weight may be assigned to W1 located in the center of the short range group.

In addition, when the near group is located in the peripheral area, that is, when the near group is G4, G5, the difference between the focal lengths between the groups and the mean of the focal lengths of the groups are compared (S135). If the distance difference is smaller than the focal length average value, a weight is assigned to the peripheral window. That is, in the case of G3 and G4, weights may be assigned to W3.W4, W5, W6, W7, and W8.

Next, the lens is transferred to a position corresponding to the window to which the weight is assigned (S150). This is performed by the driving stage 150. Next, the subject is re-photographed with an optimal focus by referring to the window to which the weight is assigned, and the signal processing is performed on the image, and then displayed. This is done by the imaging end 110 and the display end 130.

As described above, the automatic focusing method divides the captured image into a plurality of groups having the same weight and assigns weights to the groups using the maximum focus value and the focal length average value for each group and the difference in focal lengths between the groups. Focus can be easily adjusted according to the environment and distribution of the subject.

Although the preferred embodiments of the present invention described above have been described in detail, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

Accordingly, the scope of the present invention should not be limited to the disclosed embodiments but should be regarded as belonging to various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims, or the scope of the present invention. .

1 and 2 is a configuration diagram for an auto focusing apparatus according to an embodiment of the present invention.

3 is a flowchart illustrating an auto focus adjusting method according to an exemplary embodiment of the present invention.

4 is an explanatory diagram showing a plurality of windows employed in the embodiment of the present invention.

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

100: Auto Focusing Device

110: imaging stage 120: image processing stage

130: display stage 140: central processing stage

150: drive stage

Claims (10)

An imaging stage having a lens to capture an image of a subject; An image processing stage for signal processing an image picked up from the imaging stage; And And a central processing stage for dividing the signal processed by the image processing stage into a plurality of windows, and assigning weights by classifying a predetermined number of windows among the plurality of windows into one group, The central processing stage A focus value calculator configured to calculate a maximum focus value of the group; A focal length calculator for calculating a focal length of the group; And A focal length average value calculator for calculating an average of the focal lengths calculated from the focal length calculator; Auto focusing device comprising a. The method of claim 1, The central processing unit may further include a window controller for dividing the image into at least nine windows and classifying the image into at least five groups. 3. The method of claim 2, And the image comprises a central window positioned in a central region and a plurality of peripheral windows shaped around the central region. The method of claim 1, And a driving stage for driving the lens of the imaging stage according to the control signal of the central processing stage. The method of claim 1, And a display stage for displaying an image processed by the image processing stage. Capturing an image to perform signal processing, and classifying a predetermined number of windows into one group to calculate a maximum focus value and a focal length of each group; Calculating a focal length average value of each group; Extracting positions of short-range groups by analyzing the maximum focus value and the focal length; Comparing a focal length difference between the short range groups and an average focal length between the groups; And Assigning a weight to a window belonging to a short range group corresponding to the comparison result; Auto focusing method comprising a. The method of claim 6, After extracting the location of the local group, And determining whether the short range group is located in a central area. The method of claim 7, wherein In a step of comparing a focal length difference between the short range groups and a focal length average value between the groups, And comparing a case where a difference in focal length between the groups is smaller than an average value of focal lengths between the groups when the short range group is located in the center region. The method of claim 7, wherein In a step of comparing a focal length difference between the short range groups and a focal length average value between the groups, And comparing the case where the difference in focal length between the groups is smaller than the average value of the focal lengths between the groups when the near group is located in the peripheral area. The method of claim 6, After assigning a weight to a window belonging to a local group corresponding to the comparison result, And moving the lens to a position corresponding to the window to which the weight is assigned.

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