KR101362769B1 - Apparatus for processing digital image and method for controlling thereof - Google Patents

Abstract

The present invention relates to a digital image processing apparatus and a method of controlling the same, which receives an image in a continuous frame and searches for a face using a region other than the face region found in the previous frame as a search region in the current frame. The present invention comprises the steps of receiving an image in frame units at set time intervals; Determining whether there is a first region corresponding to a face region found in a previous frame; Searching for a face of a person in the entire area of the current frame when the first area does not exist; Searching for a face of a person in an area other than the first area among all areas of the current frame when the first area exists; Determining whether there is a second area corresponding to a face area found in the current frame; And storing the position of the second region.

Description

[0001] The present invention relates to a digital image processing apparatus and a control method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image processing apparatus and a control method thereof, and more particularly, to a digital image processing apparatus and a control method thereof which image-process an input image, compress and store the image as an image file.

Typically, the digital image processing apparatus includes all apparatuses that process images of a digital camera, a PDA (personal digital assistant), a phone camera, a PC camera, or the like and use an image recognition sensor.

The digital image processing apparatus can process an image received through an image pickup device in a digital signal processor, compress the image to generate an image file, and store the image file in a memory.

In addition, the digital image processing apparatus can receive input through an image pickup device or display an image of an image file stored in a storage medium on a display device such as an LCD (Liquid Crystal Display).

The input image may include a face of a person. In this case, a human face is often of interest in an image to be photographed. In this case, the human face can be focused. In this case, a face region may be detected from an image input by various needs.

An object of the present invention is to provide a digital image processing apparatus for searching for a face by receiving an image in a continuous frame and searching for a face using a region other than the face region found in the previous frame in the current frame, and a control method thereof.

The present invention comprises the steps of receiving an image in frame units at set time intervals; Determining whether there is a first region corresponding to a face region found in a previous frame; Searching for a face of a person in the entire area of the current frame when the first area does not exist; Searching for a face of a person in an area other than the first area among all areas of the current frame when the first area exists; Determining whether there is a second area corresponding to a face area found in the current frame; And storing the position of the second region.

The method may further include displaying the first region and the second region together with the input image of the current frame.

Another aspect of the invention, the image input unit for receiving an image in units of frames at a set time interval; And a controller configured to search for a face area by searching for a face of a person in an area excluding a first area corresponding to a face area found in a previous frame among all areas of the current frame.

The apparatus may further include a storage unit in which the location of the first region is stored.

The display apparatus may further include a display configured to display a second region corresponding to the first region and the face region found in the current frame together with the input image of the current frame.

According to the digital image processing apparatus and the control method thereof according to the present invention, it is possible to improve the speed of recognizing a face in an input image by reducing a search area for searching for a face in the entire image.

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

FIG. 1 is a rear view of a digital camera 100, which is an embodiment of a control device of a digital image processing apparatus and a digital image processing apparatus to which the method is applied, according to the present invention.

Referring to FIG. 1, a direction button 21, a menu-OK button 22, a wide angle-zoom button W, a telephoto-zoom button Zoom ) Button T, a display panel 25, and the like.

The direction button 21 may include a total of four buttons including an up button 21a, a down button 21b, a left button 21c, and a right button 21d. The direction button 21 and the menu-OK button 22 are keys for inputting various menus related to the operation of the digital image processing apparatus such as a digital camera.

Wide angle-zoom button (W) or telephoto-zoom button (T) widens the angle of view or narrows the angle of view depending on the input. In particular, it can be used to change the size of the selected exposure area. At this time, when the wide-angle zoom button W is input, the size of the selected exposure area is reduced, and when the telephoto-zoom button T is input, the size of the selected exposure area may be enlarged. As the display panel 25, an image display device such as a liquid crystal display (LCD) may be used.

The display panel 25 may be displayed on a display unit for displaying a best image according to the present invention or for displaying a best image and an input image whose exposure value is an automatic exposure adjustment value so that a user can select a stored image to be stored.

Meanwhile, a shutter release button 26, a flash (not shown), a power switch 28, and a lens unit (not shown) may be provided on the front or top surface of the digital camera 100. In addition, an objective lens and an eyepiece lens of the viewfinder 27 may be provided on the front and rear surfaces of the digital camera 100.

The shutter release button 26 and the power switch 28 may be included in a user manipulation unit (360 of FIG. 3) for inputting items to be manipulated by the user from the outside.

The shutter release button 26 is opened and closed to expose an image pickup element or film such as a CCD (Charge Coupled Device) to light for a predetermined time. Further, the shutter release button interlocks with an iris (not shown) to appropriately expose the subject to record the image on the imaging element.

On the other hand, the shutter release button 26 can be pressed in two stages. A first signal is generated when the shutter release button 26 is pressed at one end, and a second signal is generated when the shutter release button 26 is pressed at this end. The preparation for photographing may be completed by the first signal, and photographing may be performed by the second signal.

As an embodiment of the digital image processing apparatus to which the present invention can be applied, a digital camera, a control apparatus thereof, and a control method thereof are disclosed in U.S. Patent Application Publication No. 2004/0130650 (titled: automatic using a quadratic function of a camera A focusing method, a focusing method, and a quadratic function in camera.

The digital camera, its control device, and control method disclosed in the above-mentioned U.S. application are incorporated in this specification, and a detailed description thereof will be omitted.

2 is a block diagram of a control device 200 of a digital image processing apparatus, which is a preferred embodiment of the present invention. The control device 200 of the digital image processing apparatus can be installed inside the digital camera 100 of FIG.

Referring to the drawings, 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, a focus lens, and a compensation lens. When the user presses the wide-zoom button W or telephoto-zoom button T included in the user input unit INP, a corresponding signal is input to the microcontroller 212.

Accordingly, as the microcontroller 212 controls the lens driving unit 210, the zoom motor M _Z is driven to move the zoom lens. That is, when the wide-angle zoom button W is depressed, the focal length of the zoom lens is shortened to enlarge the angle of view, and if the telephoto-zoom button T is depressed, the focal length of the zoom lens becomes long and the angle of view becomes narrow.

Meanwhile, in the auto focusing mode, the main controller built in the digital signal processor 207 controls the lens driving unit 210 through the micro controller 212, so that the focus motor M _F is driven do. That is, the focus motor M _F is driven to move the focus lens to a position where the sharpest picture can be obtained.

The auto focus mode may be performed according to a first signal generated by pushing the shutter release button input through the user input unit INP at one time. At this time, the position of the focus lens, which receives the plurality of images while moving the position of the focus lens along the optical axis and obtains the clearest image among the plurality of images, is obtained.

The compensation lens compensates for the overall refractive index and is not driven separately. Reference symbol M _A denotes a motor for driving an aperture (not shown).

In the filter section of the optical system (OPS), an optical low pass filter removes optical noise of a high frequency component. Infra-red cut filter blocks the infrared component of incident light.

The photoelectric conversion unit OEC may include an image pickup device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor). The photoelectric conversion unit OEC converts light from the optical system OPS into an electrical analog signal.

The analog-to-digital conversion unit may include a CDS-ADC (Correlation Double Sampler and Analog-to-Digital Converter) The analog-to-digital converter processes the analog signal from the photoelectric converter (OEC), removes the high frequency noise, adjusts the amplitude, and converts the analog signal into a digital signal. Here, the digital signal processor 207 controls the timing circuit 202 to control the operations of the photoelectric conversion unit (OEC) and the analog-digital conversion unit 201.

The optical system OPS, the photoelectric conversion unit OEC, the CDS-ADC 201, and the like may be included in the image input unit 310 of FIG. 3 according to the present invention.

The real-time clock 203 provides time information to the digital signal processor 207. The digital signal processor 207 processes digital signals from the CDS-ADC device 201 to generate digital image signals classified into luminance (Y value) and chromaticity (R, G, B) signals.

A self-timer lamp, an auto-focus lamp, a mode indicating lamp, a flash standby lamp, and the like are connected to the light emitting unit (LAMP) driven by the microcontroller 212 under the control of the main controller incorporated in the digital signal processor 207 .

The digital signal processor 207 and / or the microcontroller 212 may be included in the controller (320 of FIG. 3) according to the present invention. The digital signal processor 207 and / or the microcontroller 212 may also be equipped with cache memory as temporary storage space.

Such a cache memory may be included in the first storage unit 330 of FIG. 3 where the location of the face region found in accordance with the present invention is temporarily stored. The cache memory included in the first storage unit 330 of FIG. 3 may be included in the controller 200 separately from the digital signal processor 207 and / or the micro controller 212.

The user input unit INP may include a direction button 21, a wide-angle zoom button W, a telephoto-zoom button T, and the like. The user input unit INP may be included in the user manipulation unit 360 of FIG. 3.

A digital image signal from the digital signal processor 207 is temporarily stored in a DRAM (Dynamic Random Access Memory) 204. An EEPROM (Electrically Erasable and Programmable Read Only Memory) 205 stores algorithms and setting data such as a boot program and a key input program necessary for the operation of the digital signal processor 207. In the memory card interface 206, a user's memory card can be attached and detached.

The memory card recognized through the DRAM 204 or the memory card interface 206 may be included in the second storage unit 340 of FIG. 3 in which a captured image is temporarily or nonvolatilely stored.

The digital image signal from the digital signal processor 207 is input to the display panel driver 214, thereby displaying an image on the display panel 215. [

The controller 200 of the digital image processing apparatus may further include display units 214 and 215. The display units 214 and 215 may include a display panel 215 and a display panel driver 214 for driving the display panel 215. The display units 214 and 215 may be included in the display unit 350 of FIG. 3 according to the present invention.

On the other hand, the digital image signal from the digital signal processor 207 can be transmitted by serial communication through a USB (Universal Serial Bus) connection part 31a or an RS232C interface 208 and its connection part 31b, 209 and the video output unit 31c as video signals. Here, the digital signal processor 207 may incorporate a micro controller therein.

The audio processor 213 outputs the audio signal from the microphone MIC to the digital signal processor 207 or the speaker SP and outputs the audio signal from the digital signal processor 207 to the speaker SP.

FIG. 3 is a block diagram of a digital image processing apparatus 300 according to a preferred embodiment of the present invention.

Referring to the drawings, the digital image processing apparatus 300 includes an image input unit 310; A control unit 320; Storage units 330 and 340; Display unit 350; And a user operation unit 360. The digital image processing apparatus 300 receives an image in successive frames, and finds a face in the current frame using a region other than the face region found in the previous frame as a search region.

Therefore, the search area for searching for a face among the entire images in the current frame is reduced by at least the face area found in the previous frame. Accordingly, the speed of recognizing a face in the input image can be improved.

The image input unit 310 receives an image in frame units at set time intervals. The controller 320 searches for a face of a person in an area except for an area corresponding to a face area found in a previous frame among all areas of the current frame.

The storage units 330 and 340 may include a first storage unit 330 and a second storage unit 340. The first storage unit 330 may store a location of an area corresponding to the face area found in the previous frame. The input image may be stored in the second storage unit 340.

The display unit 350 may display an area corresponding to the face region found in the previous frame and an area corresponding to the face region found in the current frame together with the input image of the current frame. The user inputs a desired command from the outside through the user manipulation unit 360.

The area corresponding to the face area found in the previous frame may be the first area, and the area corresponding to the face area found in the current frame may be the second area.

If there is no first area stored in the first storage unit 330, the face is searched in the entire area. If there is a first area stored in the first storage unit 330, the first area is searched for in the entire area of the current frame. Search for a person's face in the excluded area.

The display unit 350 may display the first region and the second region together with the input image of the current frame.

The previous frame may be a frame temporally preceding the current frame, and the next frame may be a frame temporally trailing the current frame. If the next frame becomes the current frame, the previous current frame may be the previous frame.

In this case, it is preferable that the previous frame is the immediately preceding frame immediately preceding the current frame in time, and the next frame is the immediately following frame immediately following the current frame in time.

The image input unit 310 may include an optical system (OPS), a photoelectric converter (OEC), a CDS-ADC device 201, and the like illustrated in FIG. 2. The controller 320 may include the digital signal processor 207 and / or the microcontroller 212 illustrated in FIG. 2.

The first storage unit 330 temporarily stores the location of the found face region. The first memory unit 330 may temporarily store the location of the found face region. It may include.

The second storage unit 340 may store the input image temporarily or nonvolatile, and may include a memory card recognized through the DRAM 204 or the memory card interface 206.

The display unit 350 may include the display panel 25 shown in FIG. 1 and / or the display panel driver 214 and the display panel 215 of FIG. 2. The user manipulation unit 360 may include a shutter release button 26 and a power switch 28 of FIG. 1 and / or a user input unit INP of FIG. 2.

The digital image processing apparatus 300 may be controlled by the method illustrated in the control method S700 of the digital image processing apparatus illustrated in FIG. 7.

4 to 6 show the search region 41, 51, 61 and the face region 42, 52, 62, 43, 53, 63 found in the search region, respectively. The image is shown.

4 to 6, the search region is displayed in the image of (a), and the first region 42, 52, 62 corresponding to the face region found in the previous frame and the current frame are displayed in the image of (b). Second areas 43, 53, and 63 corresponding to the found face area are displayed.

As shown in FIG. 4, when there is no first area stored in the first storage unit 330, the entire area is set as the search area 41 and the face is searched in the search area 41. Next, the second area 43 corresponding to the face area found in the current frame is displayed on the input image.

As shown in FIG. 5, when there is a first area stored in the first storage unit 330, the search area 51 is defined as an area except at least the first area 52 among all areas. Search for a face. Next, the second region 53 corresponding to the face region found in the current frame is displayed on the input image together with the first region 52 corresponding to the face region found in the previous frame.

In the next frame, as shown in FIG. 6, the search region 61 is a search region 61 except for the first region 62 among the entire regions, and the face is searched for in the search region 61. Next, the second region 63 corresponding to the face region found in the updated current frame is displayed on the input image together with the first region 62 corresponding to the face region found in the previous frame.

In this case, in the next frame, the first area may be a second area in the current frame, and the search area 61 may be a different area from the search area 51 in the current frame.

FIG. 7 is a flowchart of a control method (S700) of a digital image processing apparatus as a preferred embodiment according to the present invention. The control method S700 of the digital image processing apparatus is implemented in the digital image processing apparatus of FIGS. 2 and / or 3 and the control apparatuses 200 and 300 thereof. To this end, the control method (S700) of the digital image processing apparatus according to the present invention may be a program or algorithm stored in the storage means of FIG. 2 or implemented in the form of a semiconductor chip such as a firmware.

Therefore, in the method S700 of controlling the digital image processing apparatus, the same matters as those described for the digital image processing apparatus and the control apparatuses 200 and 300 will be referred to, and detailed description thereof will be omitted.

The control method (S500) of the digital image processing apparatus includes an image input step (S710); Determining a first region (S720); Face region searching steps S730 to S750; Face region storage step (S760, S770); And a display step (S780).

In the image input step S710, an image is input in a frame unit at a set time interval. In the first region determination step (S720), it is determined whether there is a first region corresponding to the face region found in the previous frame.

In the face region search step (S730 through S750), a face of a person is searched for in the search region. In the face region storing step (S760, S770), it is determined whether the second region corresponding to the face region found in the current frame is included in the search region (S760), and when the second region is included, the position of the second region is stored. do.

In the display step S780, the first region and the second region are displayed together with the input image of the current frame.

In this case, the first region corresponds to the face region found in the previous frame. The second area corresponds to the face area found in the current frame. In the next frame with respect to the current frame, the second area becomes a new first area.

The search area is an area for searching for a face of a person. When the first region is included in the input image, a region except for the first region may be a search region. When the first region is not included in the input image, the entire region of the input image may be a search region.

The previous frame may be a frame temporally preceding the current frame, and the next frame may be a frame temporally trailing the current frame. If the next frame becomes the current frame, the previous current frame may be the previous frame.

In this case, it is preferable that the previous frame is the immediately preceding frame immediately preceding the current frame in time, and the next frame is the immediately following frame immediately following the current frame in time.

In the first region determination step (S720), it is determined whether there is a first region corresponding to the face region found in the previous frame, and it is determined whether there is a face found in the image of the previous frame.

The first region corresponding to the face region found in the previous frame may be stored in a cache. Therefore, in the first region determination step S720, the first region corresponding to the face region found in the previous frame is found in the cache.

The face region searching step S730 to S750 includes a whole area searching step S730 and a partial area searching step S740 and S750 according to whether the first area exists.

If there is no first area in the full area search step (S730), the entire area of the current frame may be used as a search area, and a face of a person may be searched for in the search area. The partial region searching steps S740 and S750 are performed when there is no first region. The regions except for the first region may be search regions, and a face of a person may be searched in the search region.

In the partial region searching operation (S740, S750), the position of the first region corresponding to the stored face region is read in the previous frame image (S740), and the human area is searched for in the region except for the first region corresponding to the stored face region among the entire region. Search for a face. In this case, the location of the first region corresponding to the face region stored in the previous frame image may be read from the cache.

In the face area storing step (S760, S770), a human face is searched for in the search area, the presence or absence of the second area is included in the search area (S760), and the location of the second area is stored when the second area is included. do. In this case, if the second area is not included, the next step is performed without storing the location of the second area. First, it is determined whether there is newly found face information (S760), and the newly found face may be a second area corresponding to a face area found in the current frame.

Next, a display step S780 of displaying the first region and the second region together with the input image of the current frame may be performed.

In the control method (S700) of the digital image processing apparatus, an image is input in a continuous frame, and in the current frame, a face is searched using an area excluding a face area found in a previous frame as a search area.

Therefore, the search area for searching for a face among the entire images in the current frame is reduced by at least the face area found in the previous frame. Accordingly, the speed of recognizing a face in the input image can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, You will understand. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

FIG. 1 is a view showing the external appearance of a digital camera according to an embodiment of the digital image processing apparatus according to the present invention.

FIG. 2 is a block diagram schematically illustrating a control device that may be included in the digital camera of FIG. 1. Referring to FIG.

3 is a block diagram schematically illustrating a digital image processing apparatus according to a preferred embodiment of the present invention.

4 to 6 schematically show images of consecutive frames in which a search area and a face area found in the search area are displayed.

7 is a flowchart schematically showing a control method of a digital image processing apparatus according to a preferred embodiment of the present invention.

Claims (10)

Receiving an image in frame units at a set time interval; Determining whether there is a first region corresponding to a face region found in a previous frame; Searching for a face of a person in the entire area of the current frame when the first area does not exist; Searching for a face of a person in an area other than the first area among all areas of the current frame when the first area exists; Determining whether there is a second area corresponding to a face area found in the current frame; And And storing the position of the second region. The method of claim 1, And displaying the first area and the second area together with the input image of the current frame. The method of claim 1, And the previous frame is a previous frame temporally preceding the current frame. The method of claim 1, And the second area becomes the first area in a next frame with respect to the current frame. 5. The method of claim 4, And a frame immediately after the next frame is temporally followed by the current frame. An image input unit configured to receive an image in a frame unit at a set time interval; And And a control unit for searching for a face of a person in an area of the entire area of the current frame except for the first area corresponding to the face area found in the previous frame. The method according to claim 6, And a storage unit for storing the location of the first area. The method of claim 7, wherein If there is no first area stored in the storage unit, the face is searched for in the entire area. And if the first region is stored in the storage unit, searching for a face of a person in a region other than the first region among all regions of the current frame. The method according to claim 6, And the previous frame is a immediately preceding frame temporally preceding the current frame. The method according to claim 6, And a display unit which displays the first region and a second region corresponding to the face region found in the current frame together with the input image of the current frame.

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