JP3613741B2 - Digital still camera and video conference system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a digital still camera having image processing means for digitally converting a captured optical image into image data.
[0002]
[Prior art]
Some conventional digital still cameras have a recording mode for selecting and recording the image quality and the compression ratio, and can obtain an image quality suitable for the application.
[0003]
Some conventional digital still cameras can transmit captured images to a connected personal computer using serial transmission means. If this is used, it can be used as a video conference system by continuously photographing with a digital still camera and transmitting data to a connected personal computer using a power transmission means.
[0004]
[Problems to be solved by the invention]
In the above-described video conference system using a digital still camera, the digital still camera normally captures a conversation person, but sometimes captures and transmits a document or the like during the conference. At this time, the standard image quality for capturing a conversation person has a low resolution and is not suitable for shooting a document or the like, and it is necessary to switch to a high quality image quality. Moreover, if a high quality image quality is set when shooting a conversation person, the image data increases and the transmission time becomes long. Therefore, it is necessary to switch to a different image quality depending on the subject to be photographed. However, if this switching is performed manually, there is a problem that the number of switches increases and the operation becomes complicated.
[0005]
In view of such a problem, the present invention proposes a digital still camera capable of judging shooting conditions and automatically switching to an optimum image quality.
[0006]
[Means for Solving the Problems]
In the digital still camera having image processing means for digitally converting a captured optical image into image data in the present invention,
Inclination detection means for detecting the inclination of the optical axis of the photographic lens with respect to the horizontal plane, and switching means for automatically switching the image quality of the image data in accordance with the output of the inclination detection means, or
A distance measuring means for detecting a subject distance; and a switching means for automatically switching the image quality of the image data in accordance with an output of the distance measuring means, and the distance measuring means detects that the subject distance is a short distance. The switching means switches the image data to a high-quality image, and when the distance measuring means detects that the subject distance is not a short distance, the switching means changes the image data to a standard image quality. It is solved by switching .
[0007]
【Example】
An embodiment of a digital still camera according to the present invention will be described in detail with reference to FIGS.
[0008]
FIG. 1 is a block diagram of a digital still camera embodying the present invention. First, individual operations will be described.
[0009]
The image sensor unit 3 is a CCD or the like, and photoelectrically converts an optical image formed on the image sensor 3 by the optical photographing lens 1 and outputs it as an electrical signal.
[0010]
The pre-processing unit 4 is a pre-stage amplification having an AGC function, and performs basic analog processing before AD conversion such as clamping and CDS. Further, the AGC reference gain for the pre-amplification can be changed under the control of the main microcomputer 10.
[0011]
The AD conversion unit 5 converts the analog CCD output signal from the preprocessing unit 4 into digitized image data.
[0012]
The signal processing unit 6 performs processing such as filter processing, colorization processing, knee processing, and color conversion processing on the digitized CCD image data, and outputs the data to the memory controller 9 in, for example, YCrCb format. On the other hand, the signal processing unit 6 also includes a DA converter, and outputs the colorized video signal input from the AD conversion unit 5 and the image data input reversely from the memory controller 9 as analog signals. You can also. The function switching is performed by exchanging data with the main microcomputer 10, and exposure information, focus information, and white balance information of the CCD signal can be output to the main microcomputer 10 as necessary.
[0013]
In the memory controller 9, the image data input from the signal processing unit 6 is accumulated in the frame memory 11, and conversely, the image data in the frame memory 11 is output to the signal processing unit 6. The frame memory 11 is an image memory that can store image data of at least one screen. VRAM, SRAM, DRAM, etc. are generally used, but here, VRAM that can operate independently from the CPU bus is used. . Further, this memory may be shared with the system memory.
[0014]
An image storage memory 12 serving as a recording unit is a memory built in the main body, and is stored after an image photographed in the frame memory 11 is subjected to image compression processing or the like by the main microcomputer 10. As the built-in memory for storing images, there are SRAM, DRAM, EEPROM and the like, but EEPROM is preferable in consideration of storing image data in the memory.
[0015]
The PC card controller 13 connects an external recording medium such as an IC memory card and the main microcomputer 10. After the image taken in the frame memory 11 is subjected to image compression processing by the main microcomputer 10, the PC card controller 13 Data can be recorded on the external recording medium from the card controller 13 via the PC card bus 14. As an external storage IC memory card connected via the PC card controller 13, an SRAM card, DRAM card, EEPROM card, or the like can be used, and image data is directly transmitted via a public line using a modem card or ISDN card. May be transmitted to a remote recording medium.
[0016]
The strobe unit 15 is a circuit for causing the built-in strobe to emit light, and here, the light emission timing is obtained by the main microcomputer 10 that controls the photographing sequence.
[0017]
The serial port driver 16 performs signal conversion for information transmission between the camera body and the external device. There are recommended standards known by names such as RS-232-C and RS-422-A as serial transmission means, but here, RS-232-C is used.
[0018]
The sub-microcomputer 18 controls man-machine interfaces such as an operation switch of the camera body and a liquid crystal panel, and transmits information to the main microcomputer 10 as necessary. Here, a serial input / output terminal is used for information transmission with the main microcomputer 10.
[0019]
The aperture drive unit 20 is configured by, for example, an auto iris or the like, and changes the optical aperture 2 under the control of the main microcomputer 10.
[0020]
The focus drive unit 21 is configured by, for example, a stepping motor, and is for changing the position of the lens 1 under the control of the main microcomputer 10 and appropriately aligning the optical focus surface of the subject with the image sensor 3.
[0021]
The main microcomputer 10 mainly controls the sequence of shooting, recording, and playback, and further performs compressed playback of shot images and serial port transmission with external devices as necessary. Here, the JPEG method standardized by CCITT and ISO is used as the image compression. Although the main microcomputer 10 performs this calculation here, depending on the capability of the main microcomputer 10, a compression / decompression-dedicated IC may be arranged on the CPU bus.
[0022]
Next, a series of basic operations from shooting to memory recording will be described.
[0023]
The operation mode of the camera is set from various switch information connected to the sub-microcomputer 18, and information for photographing is output to the main microcomputer 10 as serial information. In accordance with this information, the main microcomputer 10 sets the memory controller 9, the signal processing unit 6, the preprocessing unit 4, and the PC card controller 13 and the serial port driver 16 as necessary.
[0024]
When the release switch S1 of the sub-microcomputer 18 is pressed, the sub-microcomputer 18 transmits the information to the main microcomputer 10. When the main microcomputer 10 knows that the S1 signal has become active, it issues an image input command to the signal processing unit 6, and the signal processing unit 6 operates the image sensor 3, the preprocessing unit 4, and the AD conversion unit 5. Receive a CCD image. After the received CCD image data is subjected to basic signal processing by the signal processing unit 6, focus information is created from the high frequency component of the luminance data and exposure data is created from the low frequency component. The main microcomputer 10 reads these data from the signal processing unit 6 and performs gain control of the AGC amplifier of the aperture driving unit 20 and the focus driving unit 21 and further the preprocessing unit 4 as necessary to obtain an appropriate exposure and focus. Converge until is obtained. Further, depending on the operation mode, an analog image signal is output from the signal processing unit 6 and output as an NTSC signal from the connector 8 to an external monitor.
[0025]
When the signal indicating that the release switch S2 has been pressed is input from the sub-microcomputer 18 to the main microcomputer 10 after the exposure value and the focus are converged to appropriate values, the main microcomputer 10 instructs the memory controller 9 to take in the instruction. Output. If necessary, a light emission signal is output to the flash unit 15 at the field timing of the captured image. When the image capture command is received by the memory controller 9, the synchronization signal from the signal processing unit 6 is detected, and image data in the YCrCb format or the like output from the signal processing unit 6 is captured in the frame memory 11 at a predetermined timing. When the frame memory 11 finishes capturing the image, the memory controller 9 displays a status indicating that the capture is complete, and the main microcomputer 10 reads this to know that the main microcomputer 10 has finished shooting.
[0026]
After the photographing is completed, the main microcomputer 10 compresses the image as necessary, and transfers the image data to the image storage memory 12, an externally connected PC card, or a personal computer connected to the external serial port 17.
[0027]
In the reproduction display operation, the main microcomputer 10 reads the image data from the image storage memory 12, an externally connected PC card, or a personal computer connected to the external serial port, and decompresses the image as necessary, and the frame memory. 11 is written. After that, when a command for displaying an image is issued to the signal processing unit 6 and the memory controller 9, the memory controller 9 reads the image data from the frame memory 11, passes through the signal processing unit 6 through the video amplifier 7, and outputs to the NTSC. An analog signal of an image is output to the connector 8 which is a terminal.
[0028]
In this way, the photographing, recording, reproduction, display, and electric transmission functions of the digital still camera are achieved.
[0029]
The tilt detecting means 22 detects the tilt of the optical axis of the taking lens, although details will be described later.
[0030]
In order to use this digital still camera in a video conference system, the above-described shooting is continuously performed and image data is transferred to a personal computer connected to the external serial port 17, or a modem card or ISDN card is used. Is used to exchange image data directly via a public telephone line.
[0031]
FIG. 2 is a front perspective view of a digital still camera incorporating the above-described configuration, and FIG. 3 is a rear perspective view of the same.
[0032]
In FIG. 2, a photographing lens 31 and an optical viewfinder objective lens window 32 are provided on the front of the camera, and a release button 33 for operating a two-stage release switch composed of S1 and S2 in the recording mode is provided on the upper surface of the camera. A power button 34 for operating the switch, a mode button 35 for operating a mode switch for switching between a recording mode and a reproduction mode, a recording mode button 36 for operating a recording mode switch for switching between a field and a frame, and a self switch for switching to a self mode in the recording mode A date button 38 for operating a date switch for switching to the date and time setting mode, a shutter button for operating a shutter switch for switching the electronic shutter to 1/60, 1/100 for flickerless and auto for program exposure. 39, described later A liquid crystal display panel 40 for displaying the number of frames to be photographed, a strobe button 41 for operating a strobe switch for switching to a flash automatic flash mode, a forced flash mode, and a flash prohibition mode are provided. An NTSC signal is externally monitored on the right side of the camera. Is provided.
[0033]
In FIG. 3, an eyepiece lens window 43 is provided on the back of the camera, and a memory card 50, which is a recording medium for recording image information, is detachable on the right side as viewed from the back. The memory card can be attached and detached as necessary.
[0034]
Next, a video conference system using the digital still camera according to the present invention will be described with reference to FIG.
[0035]
At point A, the first conversation person 62 is imaged using the digital still camera 61 having the above-described functions, and the pre-processing unit 4, the AD conversion unit 5, and the signal processing unit 6 that are image processing means as described above. Image data that has been subjected to image processing and converted into digital data is output from the external serial port 17 in FIG. 1 and input to the personal computer 63 using the transmission means RS-232-S. Subsequently, the image data is transmitted from the personal computer 63 to a point B far from the point A using a telephone line or a LAN (Local Area Network). At point B, similarly, the digital still camera 71 having the above-mentioned function is loaded with a modem card or a LAN card, and the image data of the transmitted first dialogue person 62 is transmitted via the loaded card to the digital still camera. After being input to the camera 71 and converted into an analog image signal, it is output from the connector 8 in FIG. 1 as an NTSC signal and displayed on the monitor 73.
[0036]
On the other hand, at the point B, the second still person 72 is imaged by the digital still camera 71, and is similarly transmitted from the digital still camera 71 to the point A using a telephone line or a LAN. The personal computer 63 receives the image data of the second conversation person 72 transmitted to the point A, and the image is displayed on the monitor 64.
[0037]
Next, an embodiment will be described in which the image quality mode is switched between when a conversation person is photographed and transmitted during a video conference and when a document or the like is photographed and transmitted.
[0038]
During a video conference, usually, a conversation person 62 is photographed and transmitted by a digital still camera 61 as shown in FIG. However, there are cases where the image to be transmitted is not only a conversation person but also a document 66 or a precise article as shown in FIG. When the conversation person's image is transmitted, it is sufficient if the conversation person's facial expression can be discriminated. Therefore, a standard image quality of, for example, a resolution of about 320 dpi × 240 dpi is used, and the number of shots is increased to smooth the movement of the image. You should do it. In addition, when an image such as a document is transmitted, it is better to transmit the image with a clear image with a high-quality image, for example, a resolution of about 640 dpi × 480 dpi, even if the image does not move.
[0039]
In this way, a high-quality mode that captures a subject such as a document and records or transmits high-quality image data, and a standard image quality that captures a subject such as a conversation person and records or transmits standard-quality image data. Two image quality modes are provided, and the image quality mode needs to be changed depending on the shooting conditions.
[0040]
For this reason, in the first embodiment, the inclination of the optical axis of the photographing lens is detected to detect a difference in photographing conditions. That is, when the conversation person 65 is photographed as shown in FIG. 5A, the photographing lens 61a of the digital still camera 61 is photographed while being held substantially parallel to the horizontal plane. On the other hand, when the document 66 or the like is photographed as shown in FIG. 5B, the photographing lens 61a of the digital still camera 61 is held substantially vertically. Accordingly, the digital still camera 61 may be provided with a tilt detection means 61b including a sensor such as a mercury switch for detecting the tilt of the optical axis of the photographing lens 61a. The inclination detecting means 61b is the same as the inclination detecting means 22 shown in FIG. 1, and the detected optical axis inclination data is input to the sub-microcomputer 18, and the main microcomputer 10 as the switching means is used in any image mode. Whether or not to output is determined, image data is stored in the image storage memory 12 or a PC card connected to the PC card bus 14 in the determined image mode, and transferred to a personal computer connected from the external serial port 17.
[0041]
In this case, when the digital still camera 61 is photographed while holding the optical axis of the photographing lens 61a so as to be substantially parallel to the horizontal plane , it outputs as standard image quality image data, and the light of the photographing lens 61a . When shooting with the axis held substantially perpendicular to the horizontal plane , it is output as high-quality image data.
[0042]
Note that the image quality is not limited to high resolution, and a reduction in compression rate, black and white binarized image, edge enhancement, and the like may be performed.
[0043]
As described above, FIG. 6 shows a flowchart for determining whether the optical axis tilt of the photographing lens is detected and the mode is set to the standard image quality mode or the high quality image quality mode.
[0044]
If the tilt of the optical axis of the photographic lens is displayed on the monitor, it is convenient for the user to adjust the tilt of the optical axis of the photographic lens. By operating the display on the monitor with a mouse, etc. If a mechanism capable of automatically adjusting the inclination is attached, it becomes more convenient.
[0045]
In the second embodiment, a difference in shooting conditions is detected by detecting the subject distance. That is, when shooting at a short distance from a predetermined subject distance, it is when shooting a document or a precise object, so when outputting at a high quality image and shooting at a long distance from a predetermined subject distance, Because it ’s time to shoot, it ’s output in standard quality. Also, since the distance between the digital still camera and the interlocutor is almost constant during a video conference, all images may be output with high quality when shooting at a shorter distance. This determination is performed by the microcomputer 10 of FIG. 1 as in the above-described embodiment. That is, the microcomputer 10 inputs the picked-up optical image as a signal, detects the shooting distance by the operation of the focus driving unit 21, and outputs each to the same as described above.
[0046]
As described above, FIG. 7 shows a flowchart for determining whether the subject distance is detected and the mode is set to the standard image quality mode or the high quality image quality mode.
[0047]
Furthermore, although the distance at which a document or the like is photographed is a short distance, the near distance may be macro-photographed. However, when shooting a conversation person, macro shooting is not necessary, and AF detection does not have to be performed up to the macro area.
[0048]
In addition, when it is detected that the image to be captured is an image composed of white and black, the image quality mode may be automatically switched to a high quality mode.
[0049]
In addition, when it is detected that the image to be captured is a paper-shaped square, the zoom function is performed so that the four corners of the paper square are detected and the paper size is substantially the same as the shooting size. It can also be adjusted automatically using.
[0050]
The above embodiment is not limited to the video conference system, and can be used for shooting of a normal digital still camera that does not perform electric transmission. When shooting with the shooting lens tilted downward, Since the document shooting is often performed at a short distance, the high-quality image mode can be switched to record the obtained high-quality image data in a built-in memory or an external recording medium.
[0051]
【The invention's effect】
According to the digital still camera of claims 1 to 5 of the present invention, an appropriate image quality is automatically selected according to the shooting conditions of the digital still camera, so that an optimal image is always recorded or transmitted. Can do.
[0052]
According to the video conference system of claim 6 of the present invention, since a digital still camera that automatically selects an appropriate image quality according to shooting conditions is used, an optimal image can always be transmitted.
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital still camera.
FIG. 2 is a front perspective view of the digital still camera.
FIG. 3 is a rear perspective view of the digital still camera.
FIG. 4 is a diagram of a video conference system using a digital still camera.
FIGS. 5A and 5B are diagrams when a conversation person is photographed and when a document or the like is photographed. FIG.
FIG. 6 is a flowchart for determining whether to change to a standard image quality mode or a high quality image quality mode by detecting the inclination of the optical axis of the photographing lens.
FIG. 7 is a flowchart for determining whether to select a standard image quality mode or a high-quality image quality mode by detecting a subject distance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 31, 61a Shooting lens 3 Image pick-up element 5 AD conversion part 6 Signal processing part 8, 42 Connector 10 Main microcomputer 12 Image storage memory 13 PC card controller 17 External serial port 18 Sub microcomputer 22, 61b Tilt detection means 50 Memory card 61, 71 Digital still camera 62 First dialogue 63 Personal computer 64, 73 Monitor 65 Dialogue 66 Document 72 Second dialogue

Claims (6)

In a digital still camera having image processing means for digitally converting a captured optical image into image data,
A digital still camera comprising: inclination detecting means for detecting the inclination of the optical axis of the photographing lens with respect to a horizontal plane; and switching means for automatically switching the image quality of the image data in accordance with the output of the inclination detecting means . When the detecting means detects that the optical axis of the photographing lens is substantially parallel to a horizontal plane , the switching means switches the image data to a standard image quality, and the optical axis of the photographing lens is relative to the horizontal plane. 2. The digital still camera according to claim 1, wherein when the detecting means detects that the image data is substantially vertical, the switching means switches the image data to a high quality image quality. 3. The digital still according to claim 1, further comprising: a recording unit that records the image data in a built-in memory or an external recording medium; and a transmission unit that transmits the image data to the outside. camera. In a digital still camera having image processing means for digitally converting a captured optical image into image data,
Ranging means for detecting the subject distance; and switching means for automatically switching the image quality of the image data in accordance with the output of the ranging means ;
When the distance measuring means detects that the subject distance is a short distance, the switching means switches the image data to high quality image quality, and when the distance measuring means detects that the subject distance is not a short distance The digital still camera , wherein the switching means switches the image data to a standard image quality . 5. The digital still camera according to claim 4 , further comprising: a recording unit that records the image data in a built-in memory or an external recording medium; and a transmission unit that transmits the image data to the outside . A video conference system comprising the digital still camera according to any one of claims 1 to 5.

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