KR101411908B1 - Method of controlling digital image processing apparatus performing face recognition, and image processing apparatus adopting the method - Google Patents

Abstract

The method of the present invention includes steps (a) to (c) as a method of controlling a digital image processing apparatus having a diaphragm and a focus lens and performing shooting in a face recognition mode. In step (a), when a plurality of faces are detected, focusing is performed on each of a plurality of face areas to obtain focus positions. In the step (b), the focus lens is moved to the focus position of one of the plurality of face areas. In step (c), a conversion area of the depth of focus is calculated according to the focus position of any one of the face areas, and the face areas of the focus positions included in the calculated conversion range of the depth of focus of the plurality of face areas The marking is performed.

Digital camera, face recognition, face marking

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a digital image processing apparatus and a digital image processing apparatus using the method,

The present invention relates to a control method of a digital image processing apparatus and a digital image processing apparatus employing the method, and more particularly to a digital image processing apparatus having a diaphragm and a focus lens and performing shooting in a face recognition mode And a digital image processing apparatus employing the method.

A typical digital image processing apparatus, for example, a digital camera has a diaphragm and a focus lens, and performs shooting in a face recognition mode according to a user's selection.

Face Recognition algorithms have been available since the 1970s, and a wide variety of solutions are currently in widespread use. For example, it is used in a door control system, a time and attendance management system, a real time monitoring system, a video conference, a user authentication, a file encryption, a toy, and a distance education.

Therefore, various techniques are disclosed for face recognition. For example, if fast recognition speed is required, face recognition technology using geometrical features of face is suitable. This technique is most commonly used among various face recognition technologies. The technique is to recognize faces of individuals using geometric factors such as the location, size, and distance between feature points of the face, such as eyes, nose, and mouth. Here, the geometric features are included in the final remaining elements when the resolution of the input image is lowered.

In performing photographing using the above-described face recognition algorithm, conventionally, when a plurality of faces are detected, a representative face, for example, an area of the frontmost face or the largest face among a plurality of faces, or performs marking on all detected face regions. Here, the focusing target area is a representative face among a plurality of faces, for example, the frontmost face or the largest face area.

Accordingly, when the subjects to be photographed are located at different distances from the digital image processing apparatus, the user can not know whether or not each of the remaining faces other than the focusing target face can be influenced by the focusing.

Accordingly, in association with focusing, the user can not accurately set a desired composition right before shooting.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital image processing apparatus control method and digital image processing apparatus which enable a user to precisely set a desired composition right before shooting when a large number of people are photographed.

According to another aspect of the present invention, there is provided a method of controlling a digital image processing apparatus having a diaphragm and a focus lens and photographing in a face recognition mode, the method including steps (a) to (c).

In the step (a), when a plurality of faces are detected, focusing is performed on each of the plurality of face areas to obtain focus positions.

In the step (b), the focus lens is moved to a focus position of a face region among the plurality of face regions.

In the step (c), a conversion area of the depth of focus is calculated according to the focus position of the face area, and the face areas of the focus positions included in the calculated conversion range of the depth of focus of the plurality of face areas The marking is performed.

The apparatus of the present invention is a digital image processing apparatus having a diaphragm, a focus lens, and a main controller and performing shooting in a face recognition mode. Here, the main controller operates by adopting the control method of the present invention.

According to the control method of the digital image processing apparatus of the present invention and the digital image processing apparatus employing the method, marking is performed on the face regions of the focus positions included in the conversion area of the depth of focus among the focus positions . Accordingly, the user can recognize the faces located in the focusing range and the faces not in the focusing range among the plurality of faces.

Accordingly, in association with the focusing, the user can precisely set the composition desired by himself / herself immediately before photographing.

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

Timer lamp 11, flash 12, shutter release button 13, and ASR (Advanced Shake) 13 are provided on the front and the top of the digital camera 1 as a digital image processing apparatus according to the present invention, Reduction button 16, a power button 17, a lens unit 20, a microphone MIC, and a speaker SP.

The self-timer lamp 11 operates during the set time from when the shutter release button 13 is depressed to when it starts capturing an image in the self-timer mode. In addition, the self-timer lamp 11 generates auxiliary light according to the user's selection.

The ASR mode button 16 is used to compensate for camera shake. The ASR mode button 16 is also used as a lock button. For example, when the ASR mode button 16 is pressed for less than one second, the image stabilization function is performed. When the ASR mode button 16 is pressed for more than one second, the lock function in the playback mode is performed.

The shutter release button 13 has a two-stage structure. That is, when the user operates the wide angle-zoom button 39 _W and the tele-zoom button 39 _T and then presses the shutter release button 13 by one step, the SH1 signal from the shutter release button 13 is turned on ), And the SH2 signal from the shutter release button 13 is turned on when the second stage is pressed. In the still image shooting mode and the moving image shooting mode, an image is captured after the SH2 signal is turned on. In the continuous shooting mode, the image is continuously captured while the SH1 signal is turned on.

2, a digital camera 1 according to the present invention includes function buttons 15, a camera-state lamp 22, a special-effect button 23, a camera strap hook 24, There are a connection section 25, a display panel 35, a +/- button 36, a zoom / 9 division / volume button 39, a reproduction / printer button 42 and a mode button 43.

The function buttons 15 are used by the user to perform specific functions of the digital camera 1 and are used as direction-movement buttons of the active cursor in the menu screen of the display panel 35, And is used to switch between the file and the recording medium.

The camera-state lamp 22 is used to show various operational states of the camera. The special-effect button 23 is used to set special effects on the image to be photographed. The +/- button 36 is used to adjust the shutter speed for night view shooting and the like.

The Zoom / 9 Split / Volume button 39 is used to perform a zooming operation in the shooting or playback mode, or to display nine pictures in one screen in the playback mode, or to adjust the volume of the audio .

The playback / printer button 42 is used for switching between a playback mode and a live-view mode or for direct output to a printer.

The mode button 43 is used to select a PMP (Portable Media Player) mode or various shooting modes.

Fig. 3 shows the overall configuration of the digital camera 1 of Fig. Fig. 4 shows the incident side structure of the digital camera of Fig. Referring to Figs. 1 to 4, the overall configuration and operation of the digital camera 1 of Fig. 3 will be described as follows.

An optical system (OPS) including the lens unit 20 and the filter unit 41 optically processes light from a subject. The lens portion of the optical system OPS includes a zoom lens ZL, a focus lens FL, and a compensation lens CL. In the live-view mode or the moving picture photographing mode, when the user presses the zoom / nine-division / volume button 39 included in the user input unit INP, a corresponding signal is input to the micro controller 512 . Accordingly, as the micro controller 512 controls the lens driving unit 510, the zoom motor M _Z is driven to move the zoom lens ZL.

For example, when a wide angle-zoom signal is generated, the focal length of the zoom lens ZL is shortened to increase the angle of view, and when a telephoto-zoom signal is generated, So that the angle of view is narrowed. Here, since the position of the focus lens FL is adjusted with the position of the zoom lens ZL set, the angle of view is hardly affected by the position of the focus lens FL.

Meanwhile, in the automatic focusing mode, the main controller built in the digital camera processor 507 controls the driving unit 510 through the micro controller 512 to drive the focus motor M _F. Thus, the focus lens FL is moved. In this process, the position of the focus lens, in which the luminance differences between adjacent pixels are the largest on average, is set as the number of drive steps of the focus motor M _F.

The operation algorithm of the digital camera processor 507 in the automatic focusing mode when the face recognition mode is set will be described in more detail with reference to FIGS.

The compensation lens CL of the lens unit 20 of the optical system OPS is not separately driven since it serves to compensate the overall refractive index. Reference symbol M _A denotes a motor for driving an aperture (101 in Figs. 10 and 11).

In the filter section 41 of the optical system OPS, an optical low pass filter (OLPF) removes optical noise of a high frequency content. Infra-red cut filter (IRF) blocks incoming infrared light.

A photoelectric conversion unit OEC of a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) converts light from the optical system OPS into an electrical analog signal. Here, the digital camera processor 507 controls the timing circuit 502 to control the operations of the photoelectric conversion unit (OEC) and the analog-digital conversion unit 501. A CDS-ADC (Correlation Double Sampler and Analog-to-Digital Converter) 501 as an analog-to-digital conversion section processes an analog signal from the photoelectric conversion section OEC, removes the high- , And generates digital image data.

The real-time clock 503 provides time information to the digital camera processor 507. The digital camera processor 507 processes the digital image data from the CDS-ADC 501 to generate digital image data classified into luminance and chroma signals.

The light-emitting section (LAMP) driven by the microcontroller 512 according to the control signals from the digital camera processor 507 incorporating the main controller includes a self-timer lamp 11 and a camera-state lamp 22 .

The user input unit INP includes a shutter release button 13, function buttons 15, an ASR mode button 16, a power button 17, a special-effect button 23, a +/- button 36, A zoom / nine division / volume button 39, a playback / printer button 42, a mode button 43, and the like.

In the DRAM (Dynamic Random Access Memory) 504, digital image data from the digital camera processor 507 is temporarily stored. An algorithm necessary for the operation of the digital camera processor 507 is stored in an EEPROM (Electrically Erasable and Programmable Read Only Memory) 505. In the memory card interface (MCI) 506, the user's memory card is detached. In the flash memory (FM), setting data necessary for the operation of the digital camera processor 507 is stored. In the memory card interface 506, a plurality of memory cards are detached and removed as user's recording media.

The digital image data from the digital camera processor 507 is input to the LCD driver 514, whereby the image is displayed on the display panel 35.

The digital image data from the digital camera processor 507 is transmitted through the USB (Universal Serial Bus) connection unit 21a or the RS232C interface 508 and the connection unit 21b through the serial communication in the interface unit 21 And can be transmitted as a video signal through the video filter 509 and the video output unit 21c.

The audio processor 513 outputs the audio signal from the microphone MIC to the digital camera processor 507 or the speaker SP and outputs the audio signal from the digital camera processor 507 to the speaker SP.

On the other hand, the micro controller 512 controls the operation of the flash controller 511 in accordance with the signal from the flash-light amount sensor 19 to drive the flash 12. [

FIG. 5 shows the main algorithm of the digital camera processor 507 of FIG. The main algorithm of the digital camera processor 507 of FIG. 3 will be described with reference to FIGS. 1, 3, and 5 as follows.

When operation power is applied to the digital camera 1, the digital camera processor 507 executes initialization (step S1).

When this initialization step S1 is executed, the digital camera processor 507 performs a live-view mode (step S2). In this live-view mode, the input image is displayed on the display panel 35.

When the face recognition mode is set in the following setting mode execution step S6, the face (s) are detected by the well-known face recognition algorithm in the subsequent live-view mode (step S2) Lt; / RTI >

As described above, various techniques are disclosed for face recognition. For example, if fast recognition speed is required, face recognition technology using geometrical features of face is suitable. This technique is most commonly used among various face recognition technologies. The technique is to recognize faces of individuals using geometric factors such as the location, size, and distance between feature points of the face, such as eyes, nose, and mouth. Here, the geometric features are included in the final remaining elements when the resolution of the input image is lowered.

Next, when the SH1 signal as the first stage signal from the shutter release button 13 is in the On state (step S3), the digital camera processor 507 performs the shooting mode (step S4).

Next, when signals corresponding to the setting mode are input from the input signals from the user input unit INP (step S5), a setting mode for setting the operating conditions according to the input signals from the user input unit INP is performed (Step S6).

On the other hand, if no termination signal is generated (step S7), the digital camera processor 507 determines whether a conversion signal to another arbitrary mode has been generated (step S8).

If no conversion signal to another mode is generated in step S8, the digital camera processor 507 repeats step S2 and the following steps. In step S8, if another mode, for example, a conversion signal to the reproduction mode is generated, the digital camera processor 507 repeats the step S2 and the following steps after performing the corresponding mode (step S9) do.

FIG. 6 shows an algorithm of the photographing mode execution (step S4) of FIG. Referring to Figs. 1, 3 to 6, the algorithm of the shooting mode execution (step S4) of Fig. 6 will be described as follows. The execution of this algorithm is started when the SH1 signal, which is the first stage signal from the shutter release button, is in an On state. Here, the current position of the zoom lens ZL has already been set.

First, the digital camera processor 507 checks the remaining capacity of the memory card (step S4101), and confirms whether or not it is the capacity to record the pixel data (step S4103). If not, the digital camera processor 507 indicates that the capacity of the memory card is insufficient, and ends the normal shooting mode (S43) (step S4105). In the case of recordable capacity, the following steps are performed.

First, the digital camera processor 507 performs white balance setting according to the currently set photographing conditions to set parameters related to the white balance (step S4107).

Next, in the automatic focusing mode (step S4109), the digital camera processor 507 performs automatic focusing (step S4111). The algorithm of the automatic focusing performed when the face recognition mode is set in the setting mode performing step S6 (step S4111) will be described in detail with reference to FIGS.

Next, the digital camera processor 507 continues the following steps if the SH1 signal, which is a first-stage signal from the shutter release button, is on (step S4109).

First, the digital camera processor 507 confirms whether the SH1 and SH2 signals are in an On state (steps S4113 and S4115). If the SH2 signal is not in the on state, the digital camera processor 507 repeats the steps S4113 and S4115 because the user has not pressed the second end of the shutter release button 13 for photographing. Here, if the SH1 signal is not in the On state, the shooting mode (step S4) is ended because there is no user's intention to shoot.

If the SH2 signal is on, the digital camera processor 507 generates the image file on the memory card as the recording medium since the user presses the second end of the shutter release button 13 for photographing S4117). Subsequently, the digital camera processor 507 performs image capturing (step S4119). That is, the digital camera processor 507 receives the image data from the CDS-ADC device 501. Next, the digital camera processor 507 compresses the received image data (step S4121). Then, the digital camera processor 507 stores the compressed image data in the image file (step S4123).

FIG. 7 shows an algorithm of the automatic focusing operation (step S4111) of FIG. 6 when the face recognition mode is set in the setting mode performing step S6 of FIG. FIG. 8 is a graph for explaining the principle of focusing in steps S705, S709, and S711 of FIG. FIG. 9 shows an example of an image displayed when a plurality of faces are detected in step S701 of FIG. Fig. 10 shows the depth of focus when the diaphragm closing value is large. Figure 11 shows the depth of focus and confounders when the aperture stop value is low.

In Fig. 8, reference symbol DS denotes the number of drive steps as the position of the focus lens (FL in Fig. 4). Reference numeral FV denotes a focus value that can be called an average contrast between neighboring pixel data as a result of summing up difference values between adjacent pixel data. Reference sign DS _I indicates the number of drive steps of the focus lens FL at the set upper limit position. DS _FOC denotes the number of drive steps of the focus lens FL at the position of the maximum focus value FV _MAX of the set movement areas DS _I to DS _S and DS _S denotes the number of drive steps of the focus lens FL at the set low- FL, respectively.

In FIG. 9, reference numeral 35 denotes a display panel, and reference numerals 91 and 92 denote marks for the face regions of the focus positions included in the conversion area of the depth of focus.

In FIGS. 10 and 11, reference numeral 101 denotes an aperture, P _F denotes a focus, D _F denotes a depth of focus, 112 denotes an upper surface, and 113 denotes a confusion circle.

As is well known, confusion circles 113 refer to focus ellipses that spread on top surface 112 when focus P _F is not precisely matched. Here, a confusion circle that allows a person to be focused is called a permissible confusion circle. Normally, the longitudinal direction diameter of the allowable confusion source is set to twice the unit pixel diameter of the photoelectric conversion unit (OEC).

As is well known, the depth of focus means a value of the focus range that can be achieved when the sharpness of the image is not degraded. This depth of focus is set as a result of multiplying the longitudinal direction diameter of the allowable confusion circle by the closing value of the diaphragm 101.

Here, since the focus lens moves to step unit by (FL in FIG. 4), the focus motor (the M _F 3), the depth of focus in terms of area As the depth of focus by converting the step number of the focus motor (M _F) Respectively. In the case of this embodiment, the depth of focus the D _FC, the magnification of the lens unit (20), X _FL, when referred to the D _FL moving distance (called a common unit tank emissions) of the focus lens (FL) in the single step the depth of focus D _FC in terms of area N _SS it is calculated by the equation (1) below.

Referring to FIGS. 7 to 11, the algorithm of the automatic focusing operation (step S4111) of FIG. 6 when the face recognition mode is set in the setting mode performing step S6 of FIG. 5 will be described below.

First, the digital camera processor (507 in FIG. 3) detects the face (s) by performing a face recognition mode by a well-known face recognition algorithm (step S701).

As described above, various techniques are disclosed for face recognition. For example, if fast recognition speed is required, face recognition technology using geometric features of face is suitable. This technique is most commonly used among various face recognition technologies. The technique is to recognize faces of individuals using geometric factors such as the location, size, and distance between feature points of the face, such as eyes, nose, and mouth. Here, the geometric features are included in the final remaining elements when the resolution of the input image is lowered.

After performing the face recognition mode (step S701), the digital camera processor (507 in Fig. 3) determines whether the face (s) is detected (step S703).

If the face is not detected in step S703, the digital camera processor 507 performs focusing on the setting reference area and moves the focus lens FL to the focus position (step S705). Here, the setting reference area corresponds to the central area in the case of this embodiment.

In step S705, the focus value FV for each position of the focus lens FL is calculated while the focus lens FL is moved stepwise in the set movement areas DS _I to DS _S (see FIG. 8 ). The maximum focus value FV _MAX of the set movement areas DS _I to DS _S is found out of the calculated focus values FV and the focus lens FL is moved to the position of the maximum focus value FV _MAX .

Next, the digital camera processor 507 drives the diaphragm 101 in accordance with the diaphragm closing value set in accordance with the set exposure amount (step S717). In addition, the digital camera processor 507 sets the sensitivity, i.e., the ISO (International Standards Organization) sensitivity and the shutter speed so as to obtain the set exposure dose (step S719).

Here, the EV, the sensitivity value SV, the time value corresponding to the shutter speed are set to TV, and the aperture value (Aperture Value) corresponding to the aperture stop value is set according to the average gradation of the input image. ) Is AV, the following expression (2) is applied.

EV = TV + AV - SV + 5

On the other hand, if a face is detected in step S703, the digital camera processor 507 determines whether a plurality of faces have been detected (step S707).

If a plurality of faces are not detected and only a single face is detected in step S707, the digital camera processor 507 performs focusing on the detected face area to move the focus lens FL to the focus position (step S709 ). The process of step S709 is as described in detail in step S705. However, only the analysis target area of the video data is different.

Next, the digital camera processor 507 performs marking on the detected face area (step S710).

Next, the digital camera processor 507 drives the diaphragm 101 in accordance with the diaphragm closing value set in accordance with the set exposure amount (step S717). In addition, the digital camera processor 507 sets the sensitivity, i.e., the ISO (International Standards Organization) sensitivity and the shutter speed so as to obtain the set exposure dose (step S719).

On the other hand, if a plurality of faces are detected in step S707, it is determined that the user wants to focus on the focusing before the photographing, that is, before the user presses the second end of the shutter release button 13 (refer to step S4115 in Fig. 6) To be able to set the composition precisely, the digital camera processor 507 performs the following steps.

First, the digital camera processor 507 performs focusing on each of the plurality of detected face areas to obtain focus positions (step S711). Here, the focusing process for any one face area is as described in detail in step S705. However, focusing is performed simultaneously on different face areas.

Next, the digital camera processor 507 moves the focus lens FL to the closest distance as the representative face area or the focus position of the face area at the center of the screen (step S713).

Next, the digital camera processor 507 performs marking on the face areas 91 and 92 of the focus positions included in the conversion area N _SS of the depth of focus D _FC (step S715).

Accordingly, the user can precisely set a desired composition with respect to focusing before the photographing, that is, before the user presses the second end of the shutter release button 13 for photographing (see step S4115 in Fig. 6).

Next, the digital camera processor 507 drives the diaphragm 101 in accordance with the diaphragm closing value set in accordance with the set exposure amount (step S717). In addition, the digital camera processor 507 sets the sensitivity, that is, the ISO (International Standards Organization) sensitivity and the shutter speed so as to obtain the set exposure dose (step S719).

As described above, according to the control method of the digital image processing apparatus and the digital image processing apparatus using the method of the present invention, with respect to the face regions of the focus positions included in the conversion area of the depth of focus among the focus positions Marking is performed. Accordingly, the user can recognize the faces located in the focusing range and the faces not in the focusing range among the plurality of faces. Therefore, in association with the focusing, the user can precisely set a desired composition right before shooting.

The present invention is not limited to the above-described embodiments, but can be modified and improved by those skilled in the art within the spirit and scope of the invention defined in the claims.

FIG. 1 is a perspective view showing a front side and an upper side of a digital camera as a digital image processing apparatus employing the control method according to the present invention.

FIG. 2 is a rear view showing a rear outer shape of the digital camera of FIG. 1;

FIG. 3 is a diagram showing the overall configuration of the digital camera of FIG. 1. FIG.

4 is a view showing the incident side structure of the digital camera of FIG.

5 is a flow chart showing the main algorithm of the digital camera processor of FIG.

6 is a flowchart showing the algorithm of the photographing mode execution of FIG.

7 is a flowchart showing the algorithm of the automatic focusing operation of FIG. 6 when the face recognition mode is set in the setting mode performing step of FIG.

FIG. 8 is a graph for explaining the principle of focusing in steps S705, S709, and S711 of FIG.

9 is a view showing an example of an image displayed when a plurality of faces are detected in step S701 of FIG.

10 is a view showing the depth of focus when the diaphragm closing value is large.

11 is a view showing the depth of focus and confounders when the aperture stop value is small.

 Description of the Related Art

1 ... digital camera, 11 ... self-timer lamp,

12 ... flash, 13 ... shutter release button,

15 ... function buttons, 16 ... ASR mode button,

17 ... power button, 19 ... flash-light sensor, 20 ... lens, 22 ... camera-status lamp,

23 ... special-effect button, 24 ... camera strap hook,

25 ... earphone connection, MIC ... microphone,

SP ... speaker, 35 ... display panel,

36 ... + / - button, 39 ... Zoom / 9 split / volume button,

42 ... play / printer button, 43 ... mode button,

OPS ... Optical system, OEC ... Photoelectric conversion unit, M _Z ... Zoom motor, M _F ... Focus motor,

M _A ... aperture motor, 501 ... analog-to-digital converter,

502 ... timing circuit, 503 ... real time clock,

504 ... DRAM, 505 ... EEPROM, 506 ... memory card interface, 507 ... digital camera processor, 508 ... RS232C interface, 509 ... video filter, 21a ... USB connection, 21b A lens controller for controlling the lens controller, a flash controller for controlling the flash controller, a controller for controlling the lens controller, ... audio processor, 514 ... LCD driver, 62 ... flash memory, 101 ... aperture,

P _F ... Focus, D _F ... Focus depth,

112 ... upper side, 113 ... conferees.

Claims (8)

A control method of a digital image processing apparatus having an aperture and a focus lens and performing shooting in a face recognition mode, (a) when a plurality of faces are detected, focusing is performed on each of a plurality of face regions to obtain focus positions; (b) moving the focus lens to a focus position of a face region among the plurality of face regions; And (c) calculating a conversion area of the depth of focus according to the focus position of any one of the plurality of face areas, and marking the face areas of the focus positions included in the calculated conversion area of the depth of focus A control method of the digital image processing apparatus including the control unit. The method according to claim 1, (d) driving the diaphragm according to a set diaphragm closing value. 3. The method of claim 2, wherein in step (c) Wherein the result of multiplying the longitudinal diameter of the allowable confusion circle by the set diaphragm closing value is the depth of focus. 4. The method of claim 3, wherein in step (b) And the focus lens is moved in steps by the focus motor. 5. The method of claim 4, wherein in step (c) And the converted depth of focus depth is set as the depth of focus is converted into the number of steps of the focus motor. 3. The method of claim 2, (e) setting a sensitivity and / or a shutter speed so as to obtain a set exposure amount. The method according to claim 6, (f) capturing an image when the steps (a) to (e) are performed. A digital image processing apparatus having a diaphragm, a focus lens, and a main controller and performing shooting in a face recognition mode, Wherein the main controller operates by employing any one of the control methods of claims 1 to 7.

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