JP4364464B2 - Digital camera imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital camera imaging apparatus, and in particular, has an image imaging unit that converts an optical signal from a subject into an image signal that is an electrical signal via an optical system and outputs the image signal. The present invention relates to a digital camera imaging apparatus that shifts to a person photographing mode.
[0002]
[Prior art]
In recent years, with the development of personal computers, the use of digital cameras as image input devices has become widespread. In particular, most of them are equipped with a portrait mode for photographing people, and photographing is performed by adjusting the camera mode to an optimal position depending on the subject. Therefore, techniques for automatically performing this mode selection have been proposed. For example, Japanese Patent Laid-Open No. 9-281541 discloses a camera that can automatically select an optimal shooting mode according to shooting conditions. According to this, as a photographing condition, a focal length data of the photographing lens is added, and calculation means for calculating a focal length and a photographing magnification is provided. When the photographing magnification is within a certain range, the person mode is selected. Yes.
[0003]
[Problems to be solved by the invention]
Conventionally, in a digital camera imaging apparatus having a portrait mode for photographing a person, the user has to set the mode before photographing. In addition, when photographing with a plurality of people, it is difficult to adjust the aperture so that the focus is suitable for everyone.
Japanese Patent Laid-Open No. 9-281541, which automates this, selects the person mode when the shooting magnification is within a certain range, and switches to the portrait mode when the face of the person of the present invention is detected. It is a different invention from the technology that automatically migrates. In view of such a problem, the present invention automatically shifts to the portrait mode by detecting a face image to prevent a shooting mistake due to forgetting to set, and when a plurality of persons are detected, It is an object of the present invention to provide a digital camera imaging apparatus in which all the members automatically enter the depth of field.
[0004]
[Means for Solving the Problems]
In order to solve such a problem, the present invention provides a digital camera imaging apparatus having an image imaging means for converting an optical signal obtained via an optical system into an image signal and outputting the image signal. further comprising a face image detection means for detecting a face image from the signal, if the said pigment image detection means detects a face image, will switch to the most suitable person photographing mode in portrait photography, further the face image detection means When a plurality of face images are detected, distance measuring means for measuring the distance from the size of the plurality of face images is provided, and the diaphragm is controlled based on the distance measuring means . The largest number of subjects in the camera are overwhelmingly people. Therefore, when shooting a person, it is necessary to set the most suitable setting for the shooting with the camera. The most suitable part for specifying a person is a face. If a face image can be extracted from a subject, a mode setting suitable for the face image can be set. In particular, since a digital camera digitizes and records an image signal, analysis by a computer is easy. According to this invention, when the face image detecting means detects the face image, the mode is switched to the person shooting mode most suitable for the person shooting, so that the operability is improved and the shooting failure probability is reduced. According to the first aspect of the present invention, when the face image detecting means detects a plurality of face images, the diaphragm is controlled based on the size of the plurality of face images measured by the distance measuring means, so that it is relatively easy. Distance can be measured. The invention according to claim 2 is also an effective means of the present invention that when the face image detecting means does not detect a face image, the face image detecting means switches to a preset mode. When a person is not photographed, the face image detecting means does not detect a face image. In such a case, there may be a preset mode, that is, a shooting mode most suitable for shooting a subject or a manual mode. According to this technical means, when the face image detecting means does not detect a face image, the mode is switched to a preset mode, so that the optimum mode of the subject can be selected. The face image detection means may further comprise a monitor means for confirming the accuracy of the face image detection result, and the detection precision can be confirmed by the monitor means during or after photographing. This is also an effective means of the present invention. The accuracy of detecting a face image is not necessarily 100%. Some subjects are very similar to facial features. In such a case, it is preferable if the detection accuracy can be confirmed by a monitor. According to such a technical means, since the detection accuracy can be confirmed by the monitor means, the matching between the face image detecting means and the subject can be known in advance, and the probability of shooting failure can be further reduced.
[0005]
According to a fourth aspect of the present invention, it is also an effective means of the present invention that the monitor means marks an image position detected by the face image detecting means. The part detected by the face image detecting means is a face. It is preferable to clearly know where the face is determined on the monitor. According to this technical means, since the image position detected by the face image detecting means is marked, it becomes easy to judge the accuracy of the face image detecting means. The invention according to claim 5 is also an effective means of the present invention in that the accuracy detected by the face image detecting means can be changed. The accuracy of the face image detecting means is confirmed in the third and fourth aspects, but it is more preferable if there is means for correcting the accuracy thereafter. According to this technical means, since the accuracy detected by the face image detecting means can be changed, the detection accuracy can be further improved .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. . FIG. 1 is a block diagram of a digital still camera according to an embodiment of the present invention. In this configuration, a lens 1 that collects an optical image of a subject, a diaphragm unit 2 that focuses a light beam collected by the lens 1, and a plurality of lenses (not shown) are moved and focused, or the diaphragm unit 2 is A motor driver 11 for driving, a CCD (Charge Coupled Device) 3 that photoelectrically converts an optical image that has passed through the lens 1 and the diaphragm 2, and a CDS (Correlated Double Sampling) 4 that reduces noise included in the CCD 3. An A / D converter 5 that converts an analog signal from the CCD 3 into a digital signal, a timing generator 13 that generates the timing of the CCD 3, the CDS 4, and the A / D converter 5, and image processing according to image processing parameters. A digital signal processing circuit 7 that performs the recording, a frame memory 6 that stores the recorded image and processed image, and a liquid crystal display (LCD: Liquid Crystal Display) A display unit 8 to be displayed, an image compression / expansion circuit 9 for compressing or expanding the image data processed by the digital signal processing circuit 7 to source image data, and a memory card for storing the image data compressed by the image compression / expansion circuit 9 10, a microcomputer (hereinafter referred to as a microcomputer) 14 for executing predetermined control based on a control program, an EEPROM (Electrically Erasable and Programmable Read Only Memory) 16 for storing parameters, and an operator operating the camera body The camera operation unit 17 includes a release button for performing the operation, the OSD (On-Screen Display) 15 for monitoring the number of films and the light emission state of the strobe, and the strobe 12 for illuminating the subject. The lens 1, the diaphragm 2, and the CCD 3 mainly constitute image capturing means, and the display unit 8, the digital signal processing circuit 7 and the microcomputer 14 mainly constitute monitor means, and an image capturing unit 21 shown in FIG. control unit 22, comparator unit 23, facial feature storage unit 24 constitutes a distance measuring means in the main.
[0007]
Next, an outline of the operation of the digital still camera 100 having this configuration will be described with reference to FIG. When the operator looks into the subject from a finder (not shown) and presses the release button of the camera operation unit 17, the microcomputer 14 detects the signal and drives the lens 1 and the diaphragm 2 to the motor driver 11 to thereby image the subject. Is focused on the CCD 3. If necessary, the strobe 12 is caused to emit light. A series of these operations is automatically performed by the microcomputer 14 based on sensor information (not shown). The image focused on the CCD 3 is sequentially taken out by the clock generated from the timing generator 13, and the noise contained in the data is reduced by the CDS 4. Here, the reset noise is dominant in the noise included in the output signal of the CCD. In order to reduce this noise, the reset noise is canceled by subtracting both from the video signal included in the signal period, the reset noise, and the reset noise included only in the field-through period. The analog signal is converted into a 10-bit digital signal by the A / D converter 5, input to the digital signal processing circuit 7, and temporarily stored in the frame memory 6. Then, data temporarily stored in the frame memory 6 is processed according to an instruction from the microcomputer 14 according to the parameters stored in the EEPROM 16, and the processed image is stored in the frame memory 6 again. This processing includes white balance processing. Further, the data written in the frame memory 6 is sent to the control unit of the display unit 8, and the content is displayed on the LCD.
The frame memory 6 is an image memory that can store image data of at least one screen of image pickup pixels. For example, a video random access memory (VRAM), a static random access memory (SRAM), a dynamic random access memory (DRAM). ) Or a commonly used memory such as SDRAM (Synchronous DRAM).
[0008]
Here, if the operator wants to record the image on the memory card 10 by the operator's intention, the microcomputer 14 instructs the digital signal processing circuit 7 to send the image to the memory card 10 in response to an instruction from the camera operation unit 17. The control to transfer to 10 is executed. That is, the image-processed image is read from the frame memory 6 and sent to the image compression / expansion circuit 9. Here, the image is compressed by the JPEG (Joint Photographic Experts Group) method and stored in the memory card 10. As this encoding algorithm, ADCT (adaptive discrete cosine) is used, and hierarchical encoding in which an image having a low resolution is first encoded and gradually becomes higher is also adopted. Thus, the memory card is for compressing the data stored in the frame memory 6 and storing the compressed data. In addition to this, for example, it may be configured to record in an internal memory of about 8 MB or a smart media / compact flash.
Conversely, when displaying the contents of the memory card 10 on the display unit 8 or when transferring image data by connecting to another PC via an external terminal, the desired memory card is inserted into a connector (not shown) of the camera body. Then, when instructed from the camera operation unit 17, the microcomputer 14 instructs the digital signal processing circuit 7 to read out the compressed image data of the memory card, inputs it to the image compression / decompression circuit 9, and inputs the data according to the compression algorithm. The image is expanded and restored, and an image is displayed on the display unit 8.
[0009]
FIG. 2 is a schematic block diagram of the face image detection unit according to the embodiment of the present invention. This configuration includes an image memory 20 that stores one image of a subject, an image capturing unit 21 that captures a predetermined unit from the memory into another memory or a register, a control unit 22 that controls the whole, and a plurality of A face feature storage unit 24 that stores facial features, a comparison unit 23 that compares the data from the image capture unit 21 and the data from the face feature storage unit 24 and transmits the result to the control unit 22; It is comprised from the output part 25 which outputs a result to the exterior. Here, the image memory 20 may use the frame memory 6 of FIG. Further, other parts may be realized by the microcomputer 14 of FIG. 1 or may be realized by a dedicated LSI.
Here, the accuracy of detecting a face image is not necessarily 100%. Some subjects are very similar to facial features. In such a case, if the detection accuracy can be confirmed on the monitor, the matching between the face image detection unit and the subject can be found in advance, and the probability of shooting failure can be further reduced.
The part detected by the face image detection unit is a face. If the user can clearly see where the face is determined on the monitor, it is easy to determine the accuracy of the face image detection unit. Further, the accuracy of the face image detection unit has been confirmed as described above, but it is more preferable if there is a means for correcting the accuracy thereafter. Thereby, detection accuracy can further be improved.
[0010]
Next, before describing the detection of a face image, an outline of a known face image recognition technique will be described. Note that the face recognition in the present invention does not have to be a level at which it can be reliably recognized as a conventional individual face, and a two-way recognition level of whether the subject is a face or another object is sufficient. is there. The target items in face image recognition are roughly divided into the following two.
1) Person identification: Identify who the target person is.
2) Facial expression identification: what kind of facial expression a person has is identified.
That is, the person identification of 1) is a face structure recognition and can be said to be a static identification. Also, facial expression identification in 2) is recognition of face shape change and can be said to be dynamic identification. In the case of the present invention, it can be said that the identification is simpler than the above. Further, these identification methods include 1) a two-dimensional method and 2) a three-dimensional method, and 1) a two-dimensional method is mainly used in a computer. These detailed contents are omitted here. Further, as a facial expression identification method, there is a concept based on FACS (Facial ACtion unit System), which can be expressed using the position of the feature point of the facial expression component.
In the future, it is possible to apply these technologies to room entry management systems, person image database systems, recognition communication systems, and the like.
[0011]
FIG. 3 is an operation flowchart of the first embodiment of the present invention. This will be described with reference to FIG. The subject image data is photoelectrically converted by the CCD shown in FIG. 1, subjected to image processing, and stored in the image memory 20. The image data is captured by the image capturing unit 21 in a predetermined unit (frame, byte) (S1). Next, the image data is input to the comparison unit 23 and compared with data from the face feature storage unit 24 that stores various types of face feature data stored in advance. This comparison method is performed based on various algorithms. The result is transmitted to the control unit 22 one by one, and a face image is detected (S2). As a result, when a face image is detected (YES route), the control unit 22 outputs a result signal to the output unit 25, switches the setting to the person photographing mode (S3), and presses the release button (S5). When a face image is not detected in step S2 (NO route), the control unit 22 outputs a result signal to the output unit 25, switches the setting to a preset mode (S4), and presses the release button (S5). ).
As described above, the most common subject in the camera is an overwhelming person. Therefore, when shooting a person, it is necessary to set the most suitable setting for the shooting with the camera. The most suitable part for specifying a person is a face. If a face image can be extracted from a subject, a mode setting suitable for the face image can be set. In particular, since a digital camera digitizes and records an image signal, analysis by a computer is easy. As a result, the operability is improved and the probability of shooting failure is reduced.
When a person is not photographed, the face image detecting means does not detect a face image. In such a case, there may be a preset mode, that is, a mode that is most suitable for shooting a subject or a manual mode. Thereby, the optimal mode of the subject can be selected.
[0012]
FIG. 4 is an operation flowchart of the second embodiment of the present invention. This will be described with reference to FIG. The subject image data is photoelectrically converted by the CCD shown in FIG. 1, subjected to image processing, and stored in the image memory 20. The image data is captured by the image capturing unit 21 in a predetermined unit (frame, byte) (S10). Next, the image data is input to the comparison unit 23 and compared with data from the face feature storage unit 24 that stores various types of face feature data stored in advance. This comparison method is performed based on various algorithms. The result is transmitted to the control unit 22 one by one, and a face image is detected (S11). As a result, when a face image is detected (YES route), the control unit 22 determines whether the next detected face image is plural (S12). If the number is singular (NO route), the result signal is output to the output unit 25, the setting is switched to the person photographing mode (S14), and the release button is pressed (S16). When a face image is not detected in step S11 (NO route), the control unit 22 outputs a result signal to the output unit 25, switches the setting to a preset mode (S13), and presses the release button (S16). ). If there are a plurality of cases (YES route) in step S12, a result signal is output to the output unit 25, and the control unit 22 controls the aperture so that all the faces are within the depth of field (S15), and presses the release button. (S16).
The number of face images of the subject is not limited to one. In the case of a plurality of subjects, the depth of focus of the camera lens is finite. In the case of a plurality of subjects, the distance from the camera is not constant. Therefore, it is preferable to measure the distance between the closest face image and the farthest face image with a sensor or the like and control the aperture based on the distance. As a result, the diaphragm is controlled based on the front and back distances of the plurality of face images, so that it is possible to prevent the focus from being blurred.
In addition, the size of the face and the distance do not necessarily have a correlation, but in general, it can be said that the face image is close when the face image is large, and far when the face image is small, so the distance can be measured relatively easily.
According to the first aspect of the present invention, as shown in FIG. 3, when a person's face is recognized in the image, the mode is automatically shifted to the portrait mode and shooting is performed. Thereby, forgetting of mode change setting can be prevented.
In addition, each of the above methods has advantages and disadvantages. If the distance of the face image is actually measured, the accuracy increases, but the cost increases. If the distance is determined based on the size of the face image, the accuracy is reduced, but the cost is low. Thereby, since either one of the two means can be selected, the functional variation becomes wide.
[0013]
【The invention's effect】
As described above, according to the present invention, when the face image detecting means detects a face image, the mode is switched to the person shooting mode most suitable for person shooting, so that the operability is improved and the shooting failure probability is improved. Decrease. Furthermore, when the face image detecting means detects a plurality of face images, the diaphragm is controlled based on the size of the plurality of face images measured by the distance measuring means, so that the distance can be measured relatively easily. . According to the second aspect, when the face image detecting means does not detect a face image, the mode is switched to a preset mode, so that the optimum mode of the subject can be selected. According to the third aspect of the present invention, since the detection accuracy can be confirmed by the monitor means, the matching between the face image detection means and the subject is known in advance, and the probability of shooting failure can be further reduced. According to the fourth aspect, since the image position detected by the face image detecting means is marked, it becomes easy to judge the accuracy of the face image detecting means. Since the accuracy detected by the face image detecting means can be changed, the detection accuracy can be further increased .
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital still camera according to an embodiment of the present invention.
FIG. 2 is a schematic block diagram of a face image detection unit according to the embodiment of the present invention.
FIG. 3 is an operation flowchart according to the first embodiment of the present invention.
FIG. 4 is an operation flowchart of the second embodiment of the present invention.
[Explanation of symbols]
20 image memory, 21 image capture unit, 22 control unit, 23 comparison unit, 24 face feature storage unit, 25 output unit

Claims (5)

In a digital camera imaging apparatus having an image imaging means for converting an optical signal obtained via an optical system into an image signal and outputting the image signal,
A face image detecting means for detecting a face image from the image signal;
If said pigment image detection means detects a face image, it will switch to the most suitable person photographing mode in portrait photography,
Furthermore, when the face image detecting means detects a plurality of face images, the digital camera is provided with a distance measuring means for measuring a distance from the size of the plurality of face images, and the aperture is controlled based on the distance measuring means. Imaging device.   2. The digital camera imaging apparatus according to claim 1, wherein when the face image detecting means does not detect a face image, the face image detecting means switches to a preset mode.   The face image detection means further comprises a monitor means for confirming the accuracy of the face image detection result, and the detection accuracy can be confirmed by the monitor means during or after photographing. 2. The digital camera imaging device according to 2.   The digital camera imaging apparatus according to claim 1, wherein the monitor unit marks an image position detected by the face image detection unit.   The digital camera imaging apparatus according to claim 1, wherein the accuracy detected by the face image detection means can be changed.

Images