JP4063583B2 - Digital camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital camera and an image processing method thereof.
[0002]
[Prior art]
FIG. 8 is a perspective view of a conventional digital camera, and FIG. 9 is a block diagram showing an internal configuration of the conventional digital camera (see Japanese Patent Application Laid-Open No. 2001-313680). The camera body (1) is provided with a strobe (70) and a shutter button (10) as is well known.
An objective lens (30) having a rack (31) is provided in the camera body (1), and the rack (31) can be moved closer to and away from the subject by a motor M via a gear train (32). Is provided. Light from the objective lens (30) is converted into an electrical signal by the CCD (33), converted to a digital signal by the A / D converter (34), and color correction and gamma correction are performed by the signal processing circuit (35). And the like are input to the control circuit (2). The control circuit (2) supplies power to the motor M. The objective lens (30), CCD (33), A / D converter (34), motor M, and gear train (32) constitute a known autofocus mechanism (3).
[0003]
In the middle of pressing the shutter button (10) or in the half-pressed state in which the shutter button (10) is lightly pressed, the control circuit (2) once energizes the motor M and moves the objective lens (30) along the optical axis L. Move little by little. When the objective lens (30) slightly moves from the focused state, the electrical signal from the CCD (33) becomes a waveform with a undulating undulation as shown in FIG. 10 (a). It is known that when the lens (30) moves, the electrical signal from the CCD (33) has a gentle waveform as shown in FIG. 10 (b). The control circuit (2) stops the objective lens (30) and focuses at the point where the waveform of the electric signal is most undulating.
When the shutter button (10) is fully depressed in this state, the flash (70) emits light, and the image of the subject passes through the control circuit (2) and is stored in the image memory (4).
[0004]
[Problems to be solved by the invention]
When the subject is a person's face, the person often closes his eyes reflectively when the strobe (70) emits light during shooting. That is, a photograph with closed eyes can be taken carelessly. To take a photo with open eyes, it is common to take several photos of the same face in succession, and then select a photo that does not have eyes closed after taking the photo.
In view of this point, a camera that automatically takes a photo with no eyes closed is disclosed in Japanese Patent Laid-Open No. 7-295063. This utilizes a so-called red-eye phenomenon in which the subject's eyes appear red when the flash is fired, leaving a photograph where the subject's eyes appear red and automatically canceling the photo where the subject's eyes do not appear red.
However, when the flash is not used, a photograph with the subject's eyes closed is taken. In addition, photos with closed eyes are automatically canceled, so if a subject who has closed their eyes shows a definitive moment of another subject, that photo is also canceled. On the other hand, usability was bad.
An object of the present invention is to provide a camera that allows a photographer to easily select and take a picture with open eyes.
[0005]
[Means for solving the problems]
The camera body (1) has a shutter button (10), an image memory (4) capable of storing a digital image of the subject captured from the objective lens (30) for each frame, and an operation of the shutter button (10). The control circuit (2) for storing the digital image of the subject in the image memory (4), the notification lamp ( 7 ) connected to the control circuit ( 2 ) and facing the subject, and the image data in the image memory (4) While performing binarization processing, the eye position detection circuit (5) for searching the eye area and the eye area detected by the eye position detection circuit (5) are continuously monitored for a specific number of frames. When the pupil portion in the region becomes small, a blink detection circuit (50) for emitting a signal to that effect is provided.
The control circuit (2) is connected to the blink detection circuit (50), and when receiving a signal indicating that the pupil is small from the blink detection circuit (50), the control circuit (2) emits the notification lamp ( 7 ). After drawing the attention of the subject, the digital image of the subject is stored in the image memory ( 4 ) .
[0006]
[Action and effect]
When the subject closes his eyes, that is, blinks, the blink detection circuit (50) detects that the pupil part indicating the black eye part has become small. The control circuit (2) receives a signal from the blink detection circuit (50) indicating that the pupil portion has become small , emits a notification lamp ( 7 ) to draw the attention of the subject , and then stores the digital image of the subject in the image memory. Store in (4). Thereby, it is possible to easily take an image of a subject with open eyes.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
1A is a perspective view of the camera body 1, and FIG. 1B is a perspective view of FIG. 1A viewed from behind. On the camera body (1), in addition to the shutter button (10) and strobe (70), there is provided a changeover switch (SW) operated when a binary image is to be processed. The camera body (1) is provided with an opening (11) into which a memory card (9) capable of storing a digital image is inserted. The taken image can be confirmed on a liquid crystal panel (8) provided on the back of the camera body (1). Three notification lamps (7) are provided on the front surface of the camera body (1) at the top and bottom, but the number is not limited to three. This example is characterized in that the photographer can easily select a photograph with the subject's eyes open.
[0008]
FIG. 2 is an internal block diagram of the digital camera of this example. As in the prior art, the autofocus mechanism (3) is connected to the control circuit (2) via the signal processing circuit (35). The control circuit (2) includes a ROM (20) in which a program is stored, a timer (6) for measuring time, a RAM (21) in which timer time and figures to be displayed on the liquid crystal panel (8) are stored, digital An image memory (4) for storing images is connected. The control circuit (2) is connected to the liquid crystal panel (8) via a D / A converter (80) and a memory card (9) via a compression / decompression circuit (90). Since the control circuit (2) is generally composed of a microcomputer, the timer (6) may be formed by dividing the clock in the microcomputer.
In the image memory (4), an eye position detection circuit (5) for binarizing the subject image to detect the eye position of the subject, and continuously monitoring the eye position of the subject, A blink detection circuit (50) for detecting that the button is closed is connected.
[0009]
When shooting normally, the photographer points the objective lens (30) (see FIG. 9) of the autofocus mechanism (3) toward the subject and presses the shutter button (10). The control circuit (2) temporarily stores a digital image of one frame in the image memory (4), and displays the image converted into an analog form by the D / A converter (80) on the liquid crystal panel (8). At the same time, the digital image is compressed by the compression / decompression circuit (90) and stored in the memory card (9). Images are stored by storing them in the memory card (9).
When the photographer operates the playback button (not shown) on the camera body (1) to instruct playback of the image in the memory card (9), the compression / decompression circuit (90) causes the memory card (9) to play back. The image inside is expanded and displayed on the liquid crystal panel (8) via the D / A converter (80).
When the photographer takes only an image with the subject opening his eyes, he operates the changeover switch (SW) to set the blink detection mode.
[0010]
(Blink detection)
When the photographer operates the changeover switch (SW) to select the blink detection mode, the control circuit (2) reads the blink detection mode program from the ROM (20). The camera body (1) issues a warning to the photographer when it detects that the eyes are closed. Hereinafter, a procedure for detecting a state where the eyes are closed will be described with reference to the flowchart of FIG. 5 and FIGS. 3 and 4.
First, the photographer points the objective lens (30) toward the subject and presses the shutter button (10) (S2). From the autofocus mechanism (3), the subject image for one frame shown in FIG. 3A is stored in the image memory (4) through the control circuit (2). The image is raster-scanned by the eye position detection circuit (5) and converted into 256-gradation digital data in which the white peak portion is 255 and the blackest portion is 0. Next, the image is binarized at a specific threshold level, and noise is removed by performing well-known labeling processing and smoothing by shrinkage / diffusion (S3). The threshold level is arbitrarily determined, but is a level in which the human skin color is white. Further, in FIG. 3A, the number of pixels is 500 pixels in both the vertical and horizontal directions, but is not limited to this.
[0011]
Various methods have been proposed for identifying a face from a binarized image and detecting the position of the eyes and the blinking state. This specifies the position of the eye from the nostril, but this is an example and is not limited to this method.
By the binarization processing, as shown in FIG. 3B, the head outline AT of the subject, the face outline KA, and the hairline H, which are continuous lines connected with pixels, are obtained. . Since the line AT and the line KA, and the line H and the line KA are connected in a ring shape, it can be seen that these lines are contour lines or hairline lines. Of course, the image of eyebrows and lips is also binarized, but is not shown in FIG. 3B for convenience. The procedure so far is described in JP-A-4-174309.
[0012]
Next, in the binarized image, a search is made for a substantially central portion of the portion surrounded by the face outline KA and the hairline H. Two black portions arranged almost horizontally are extracted in a region indicated by a one-dot chain line in FIG. 3B, and these two black portions are detected as nostrils. In order to confirm that these two black portions are nostrils, it is detected that the black portions are below the center of the region surrounded by the head outline AT and the face outline KA.
That is, the position of the nostril varies among individuals, but the nostril is located at the approximate center of the area surrounded by the face outline KA and the hairline H. In addition, the nostril is located below the center of the region surrounded by the head outline AT and the face outline KA, so that the nostril of the subject is accurately detected by the above process. Note that the shape of a general nostril may be stored as a template, and a portion of the binarized face image that matches the template may be detected as a nostril.
[0013]
Next, in the vicinity of the nostril, two black portions (portion R indicated by a one-dot chain line in FIG. 3C) having a larger interval than the nostril are detected obliquely above the position of the nostril. S4). Since both eyes are above the nose and the distance between both eyes is wider than the distance between the two nostrils, it can be seen that the two detected black parts are the eyes, that is, the pupil part. In this case, there are eyebrows as a black part wider than the distance between the two nostrils, but the eyes are on the nose side of the eyebrows, and both eyes are first detected as two black parts above the nose. There is no false detection. JP-A-10-63850 describes that the position of the eye is detected based on the position of the nostril.
The eye position detection circuit (5) finishes the operation of detecting the eye position, but the operation of binarizing the image for each frame successively taken into the image memory (4) is continued. When the position of the eye is determined by detecting the pupil part, the blink detection circuit (50) is activated.
[0014]
The blink detection circuit (50) continues to monitor the region R from the binarized image for a predetermined time, specifically, several hundred frames (S5). As shown in FIG. 4, when a person who is a subject closes his eyes, the pupil portion is covered with eyelids. Since the pupil part is a linear part where the upper and lower eyelids are combined, the area of the black part which is the pupil part is reduced (S6). The blink detection circuit (50) detects that the subject blinks and closes his eyes.
When the control circuit (2) receives a signal indicating that the subject has closed his eyes from the blink detection circuit (50), a display indicating that the eyes are closed is displayed on the image displayed on the liquid crystal panel (8). For example, the photographer is warned with a cross mark read from the RAM (21) (S7). When the photographer knows that he has taken an image with his eyes closed, he can take an image with his eyes open with high probability by pressing the shutter button (10) once more. The control circuit (2) automatically stores another image in the image memory (4) or memory card (9) after receiving a signal from the blink detection circuit (50) that the subject has closed his eyes. May be.
The photographer may delete the image if the image for which the warning has been received is unnecessary, or may leave the image if necessary, such as when a definitive moment of another subject is shown. Accordingly, upon receiving such a warning, the photographer can easily select and take a picture with his eyes open. Further, it is possible to detect that the eyes are closed without causing the strobe to emit light.
Even if the eye is initially closed at the eye position detected by the eye position detection circuit (5), the blinking detection circuit (50) continues to monitor the region R, so that the pupil portion becomes larger thereafter. If it is detected that the pupil portion has become smaller, it can be seen that there was blinking.
[0015]
(Second embodiment)
In this example, as shown in the flowchart of FIG. 6, the procedure until the blinking is detected is the same as above (S10, S11). However, if it is detected that the subject's eyes are closed, the warning lamp (7) is caused to emit light without generating a warning, and the attention of the person who is the subject is drawn (S12). The subject was surprised and opened their eyes. Thereafter, the captured image is stored in the image memory (4) (S13). The time from when the notification lamp (7) is emitted until the captured image is stored in the image memory (4) is determined in advance in the control circuit (2), and is shorter than a general human blink interval. Determined. Thereby, it is possible to easily take an image of a subject with open eyes. The light emission time of the notification lamp (7) is considered to be about 1 second to keep the subject's eyes open.
When shooting in a dark place, instead of the notification lamp (7), the strobe (70) may be fired twice to open the eyes of the person who is the subject. The strobe (70) is stronger than the notification lamp (7), and the subject closes his eyes for the first time with the first light emission, but opens his eyes immediately. At this time, the strobe (70) is fired again, and the captured image is stored in the image memory (4).
[0016]
The first light emission confirms whether the second light emission is performed without failure. In a conventional digital camera, as shown by a dashed line in FIG. 1 (a), a sensor (12) is provided on the front surface of the camera body (1), and the strobe (70) is emitted once. A sensor (12) senses the amount of light reflected from the subject. When the amount of reflected light reaches a sufficient level, the strobe (70) is prevented from emitting light longer.
However, in the digital camera proposed by the applicant, the sensor (12) is not provided to reduce the number of components. Instead, the strobe (70) is first caused to emit light, and the amount of light reflected by the subject is received by the CCD (33) of the autofocus mechanism (3). Next, the control circuit (2) compares the amount of light emitted from the strobe (70) and the amount of reflected light, calculates the amount of light emitted for the second time, and calculates how well the subject can be taken. Is emitting light.
[0017]
(Third embodiment)
In the digital camera of this embodiment, instead of causing the notification lamp (7) or the like to not emit light, the interval time t for blinking is measured, and the captured image is stored in the image memory (4) within the interval time t. In this case, the photographer presses the shutter button (10) halfway, that is, lightly presses the shutter button (10) for a while to the extent that the autofocus operation works, and then pushes the shutter button (10). The procedure is shown in the flowchart of FIG.
The photographer operates the selector switch (SW) (S20), selects the blink detection mode, and then presses the shutter button (10) halfway. At this time, the control circuit (2) does not yet store the captured image in the image memory (4).
When the blink detection circuit (50) detects blinking of the subject (S21), the blink detection circuit (50) activates the timer (6) (S22). After blinking, black eyes are exposed and the pupil portion becomes large, and when blinking again, the pupil portion becomes small again. The blink detection circuit (50) measures the time t from the previous blink to the present blink by the timer (6) (S23, S24), stores the measured data in the RAM (21), and this time. Tell the control circuit (2) that there was a blink. The blink detection circuit (50) may measure the blink time interval t a plurality of times and store the average value in the RAM (21).
[0018]
When the photographer presses the shutter button (10), the control circuit (2) reads the blinking interval time t from the RAM (21), and at the time t from the latest blink transmitted from the blink detection circuit (50). It is determined whether or not elapses (S25). If the time t has not elapsed, the captured image input from the autofocus mechanism (3) is stored in the image memory (4) (S26). If the time t has elapsed, the blink detection circuit (50) waits for information indicating that the next blink has occurred, and stores the captured image in the image memory (4) from the information within the time t. Thereby, it is possible to easily take an image of a subject with open eyes.
[0019]
The autofocus mechanism (3) generally focuses near the center of the objective lens (30). Therefore, in the blink detection mode, when a large number of people appear in the image, the blinking state of the person shown in the center of the image is determined. If there are a plurality of people in the image, the image recognition area may be limited automatically or manually so that a person whose face is greatly reflected in the center may be recognized as an image.
Even if the autofocus mechanism (3) is not provided, the center of the image may be focused by manual operation. The contents of the present application can also be used for a pan focus machine in which the aperture of the objective lens (30) is reduced to increase the depth of field.
[0020]
In the above embodiment, the blink detection mode is selected by operating the selector switch (SW) on the camera body (1). Instead, it is selected from a menu displayed on the liquid crystal panel (8). May be.
Further, it is possible to always detect blinking without providing the changeover switch (SW). In this case, whether or not the subject is a person is first detected by detecting the color or gloss of the subject and determining whether or not the subject is skin color. A technique for determining whether or not the subject is a face by detecting the skin color is disclosed in JP-A-11-281661.
[0021]
The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.
[Brief description of the drawings]
FIG. 1A is a perspective view of a camera body, and FIG. 1B is a perspective view of FIG.
FIG. 2 is an internal block diagram of the digital camera of this example.
FIGS. 3A, 3B, and 3C are diagrams illustrating a binarization process.
FIG. 4 is a diagram illustrating a binarization process for a subject with closed eyes.
FIG. 5 is a flowchart showing a procedure for detecting a state where the eyes are closed;
FIG. 6 is a procedure for taking an image with open eyes according to another embodiment.
FIG. 7 is a procedure for taking an image with open eyes according to another embodiment.
FIG. 8 is a perspective view of a conventional digital camera.
FIG. 9 is a block diagram showing an internal configuration of a conventional digital camera.
FIGS. 10A and 10B are diagrams showing current waveforms from a CCD. FIGS.
[Explanation of symbols]
(2) Control circuit
(4) Image memory
(5) Eye position detection circuit
(6) Timer
(10) Shutter button
(30) Objective lens
(50) Blink detection circuit

Claims (2)

Shutter button (10),
An image memory (4) capable of storing a digital image of a subject captured from the objective lens (30) for each frame;
A control circuit (2) for storing a digital image of the subject in the image memory (4) in response to an operation of the shutter button (10);
A notification lamp (7) connected to the control circuit (2) and facing the subject;
An eye position detection circuit (5) for binarizing the image data in the image memory (4) and searching for an eye region;
The eye position detection circuit (5) continues to monitor the eye area for a specific number of frames, and when the pupil portion in the eye area becomes smaller, the blink detection circuit (50) emits a signal to that effect. And
The control circuit (2) is connected to the blink detection circuit (50), and when the blink detection circuit (50) receives a signal indicating that the pupil portion has become small, the control circuit (2) causes the notification lamp (7) to emit light. A digital camera which stores a digital image of a subject in an image memory (4) after drawing attention of the subject. Shutter button (10),
A strobe (70) that emits light to the subject during shooting,
An image memory (4) capable of storing a digital image of a subject captured from the objective lens (30) for each frame;
A control circuit (2) for storing a digital image of the subject in the image memory (4) in response to an operation of the shutter button (10);
An eye position detection circuit (5) for binarizing the image data in the image memory (4) and searching for an eye region;
The eye position detection circuit (5) continues to monitor the eye area for a specific number of frames, and when the pupil portion in the eye area becomes smaller, the blink detection circuit (50) emits a signal to that effect. And
The control circuit (2) is connected to the blink detection circuit (50). When the signal indicating that the pupil part is small is received from the blink detection circuit (50), the flash circuit (70) is caused to emit light. A digital camera characterized by storing a digital image of a subject in an image memory (4) by causing the strobe (70) to emit light again after drawing attention of the subject.

Images