JP4131020B2 - Digital camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of a recording operation in a digital camera.
[0002]
[Prior art]
In the recording operation of the digital camera, when the shutter button is fully pressed, processing such as sweeping out unnecessary charges accumulated in the CCD is performed, and then shooting of the subject image is executed. That is, the time from when the shutter button is fully pressed to when the recording operation is actually executed is longer than when the silver halide camera is used. For this reason, for example, when a camera is pointed from behind a person and an attempt is made to take a picture of the moment the person turns around, the timing of pressing the shutter button is delayed, and it is easy to miss a photo opportunity.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a digital camera that can surely take a desired photograph even when a subject moves fast.
[0004]
[Means for Solving the Problems]
The digital camera according to the present invention extracts a reference image corresponding to at least a part of a screen to be photographed, and obtains a reference value indicating characteristics of the reference image, and a predetermined value after the reference value is obtained. A comparison image extraction means for extracting a comparison image in the same area as the reference image from the screen to be photographed every time and obtaining a comparison value indicating the characteristics of the comparison image, and a result of comparing the reference value and the comparison value And a recording operation control means for executing a recording operation.
[0005]
The reference image and the comparison image are, for example, images at the center of the screen to be shot. When a person is a subject, the person is often located in the central portion of the monitor image. In such a case, it is preferable to extract the reference image and the comparison image from the central portion of the monitor image.
[0006]
The reference value and the comparison value are, for example, data indicating the color of the subject, and are preferably average values of color difference data relating to pixels constituting the reference image and the comparison image. Further, the reference value and the comparison value are the average values of the color difference data relating to the pixels constituting the reference image and the comparison image, respectively, and the photographing control means makes the absolute value of the difference between the reference value and the comparison value larger than the predetermined value. In this case, a recording operation may be executed.
[0007]
The recording operation control means may execute the recording operation after a predetermined time has elapsed after obtaining the result of comparing the reference value and the comparison value. Thereby, the time for various processes executed before the recording operation in the digital camera is adjusted, and a desired photograph can be obtained more accurately. Further, the recording operation control means may perform photographing and recording operations with the aperture set to an open state. According to this, photographing is performed at a high shutter speed, so that a photograph with less blur can be obtained.
[0008]
The digital camera according to the present invention is characterized in that a recording operation is performed when a change amount per unit time of an image in a predetermined portion of a screen to be photographed exceeds a predetermined value.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a digital camera to which an embodiment of the present invention is applied as viewed from the rear.
[0010]
This digital camera is a compact camera, and the photographing lens 11 is fixed at the center of the front surface of the camera body 90. An optical viewfinder 91 is provided at the center of the upper portion of the camera body 90, and a liquid crystal panel (image LCD) 46 is provided at the approximate center of the back surface 92. On the liquid crystal panel 46, an image obtained by the photographing lens 11 is displayed as a moving image, and a still image recorded on a recording medium (not shown) such as a PC card by a recording operation can be displayed. A mode setting switch 95 is provided beside the liquid crystal panel 46. The mode setting switch 95 is provided for setting various operation modes, and is a jog dial in this embodiment.
[0011]
When the camera body 90 is viewed from the back, a shutter button 93 and a status display device 56 are provided on the right side of the upper part of the camera body 90. When the shutter button 93 is half-pressed, photometry, distance measurement, etc. are performed, and when it is fully pressed, a still image is recorded on the PC card. The status display device 56 is composed of a liquid crystal display element, and various setting states of the digital camera are displayed as characters or symbols on the liquid crystal display element.
[0012]
A card slot 96 is formed on the side surface of the camera body 90. The card slot 96 is provided for inserting a PC card into the camera body 90, and a card connector (not shown) into which the PC card is inserted is provided inside the card slot 96.
[0013]
FIG. 2 is a block diagram mainly showing an electrical configuration of the digital camera. The operation of this camera is controlled by a system control circuit 31 having a microcomputer. That is, under the control of the system control circuit 31, a moving image or a still image is displayed on the liquid crystal panel 46, and a still image is recorded on the PC card.
[0014]
The taking lens 11 is electrically connected to an electric circuit provided in the camera body 90 (FIG. 1). A front lens group 15 and a rear lens group 16, which are imaging optical systems, are provided in the lens barrel of the photographic lens 11, and a diaphragm 17 is provided between these lenses 15 and 16. Focus adjustment for each of the lenses 15 and 16 is performed by a lens control circuit (not shown), and the lens control circuit operates according to a control signal sent from a system control circuit 31 provided in the camera body. The aperture 17 operates according to a control signal sent from an aperture drive circuit 32 provided in the camera body, and the opening of the aperture 17 is adjusted. The aperture driving circuit 32 is controlled by the system control circuit 31.
[0015]
In the camera body, an infrared cut filter 26 and an optical low-pass filter 27 are provided on the optical axes of the lenses 15 and 16, and a CCD (imaging device) 33 is provided behind the optical low-pass filter 27. In the photographing operation, light taken from the photographing lens 11 is irradiated on the light receiving surface of the CCD 33. That is, an image obtained by the lenses 15 and 16 is formed on the light receiving surface, and the CCD 33 generates an imaging signal corresponding to the image.
[0016]
A pulse signal generation circuit (PPG) 36 is connected to the system control circuit 31, and the pulse signal generation circuit 36 generates various pulse signals under the control of the system control circuit 31. Based on these pulse signals, the CCD drive circuit 37, the correlated double sampling (CDS) circuit 34, the A / D converter 35, the color separation / interpolation processing circuit 38, and the YUV conversion circuit 39 are driven. That is, the operation of the CCD 33 is controlled by the CCD drive circuit 37, and the image pickup signal read from the CCD 33 is subjected to noise removal in the correlated double sampling circuit 34 and converted into digital image data by the A / D converter 35. The The image data is subjected to predetermined image processing in a color separation / interpolation processing circuit 38, and is separated into red (R), green (G), and blue (B) and is subjected to interpolation processing. As a result, R, G, and B image data having the same number of pixels as the CCD 33 are obtained. The R, G, B image data is converted by the YUV conversion circuit 39 into luminance data (Y) and color difference data, that is, U data (= BY) and V data (= RY).
[0017]
The luminance data, U data, and V data output from the YUV conversion circuit 39 are input to the system control circuit 31 and temporarily stored in the image memory 40. An image extraction control signal is output as a pulse signal from the pulse signal generation circuit 36 to the system control circuit 31. The system control circuit 31 applies predetermined luminance data, U data, and V data based on the image extraction control signal. This processing is performed, and a captured image recording operation to be described later is executed.
[0018]
Luminance data, U data and V data stored in the image memory 40 are read out and input to a liquid crystal (LCD) display circuit 44. A liquid crystal panel (LCD) 46 is connected to the liquid crystal display circuit 44. In the liquid crystal panel 46, the liquid crystal display circuit 44 is controlled based on luminance data, U data, and V data read from the image memory 40. As a result, a still image is displayed. In the liquid crystal panel 46, the liquid crystal display circuit 44 is controlled based on the luminance data, U data, and V data directly input from the YUV conversion circuit 39, whereby a monitor image that is a moving image is displayed.
[0019]
The luminance data, U data, and V data read from the image memory 40 are compressed by the JPEG processing circuit 41 according to the JPEG algorithm and recorded on the PC card 43 via the card control circuit 42. The system control circuit 31 controls the storage and reading operation of luminance data and the like with respect to the image memory 40, the compression operation of the JPEG processing circuit 41, and the recording operation of the PC card 43 in the card control circuit 42.
[0020]
A photometric sensor 52 is connected to the system control circuit 31. The photometric sensor 52 performs photometry to determine the opening of the diaphragm 17 during exposure and the charge accumulation time (exposure time) in the CCD 33.
[0021]
The system control circuit 31 is connected to a photometric switch 54 and a release switch 55. The metering switch 54 is turned on by half-pressing the shutter button 93, whereby the metering sensor 52 performs metering. The release switch 55 is turned on when the shutter button 93 is fully pressed, whereby the electronic shutter of the CCD 33 is on / off controlled. That is, the CCD 33 is exposed, and an imaging signal corresponding to the image is generated on the CCD 33.
[0022]
Further, a mode setting switch 95 is connected to the system control circuit 31. As described above, the mode setting switch 95 is a jog dial. When the jog dial is set at a predetermined rotational position, a predetermined mode is selected from the setting menu displayed on the liquid crystal panel 46, and when the jog dial is pressed, the mode is changed. Is set.
[0023]
FIG. 3 is a flowchart of an image recording routine in the “turning shot mode” suitable for photographing a moment when a person turns, for example. This image recording routine is executed when the turning shot mode is set by operating the mode setting switch 95.
[0024]
Step 101 is repeatedly executed until the photometric switch 54 is set to the on state. When the photometric switch 54 is switched to the on state, the process proceeds to step 102, where the aperture value and shutter speed are obtained based on the photometric value obtained by the photometric sensor 52. In step 103, the diaphragm drive circuit 32 is driven, and the diaphragm 17 is set to the opening of the diaphragm value obtained in step 102. In step 104, it is determined whether or not the release switch 55 is set to an on state. When the release switch 55 is set to an on state, the process proceeds to step 105.
[0025]
In step 105, a reference image corresponding to a part of the screen to be photographed is extracted based on the imaging signal read from the CCD 33 when the release switch 55 is switched to the on state. As shown in FIG. 4, the reference image F1 is the central portion of the screen F0 to be shot, and in the turn shot mode, the face of a person is located. In step 105, color difference data corresponding to each pixel of the reference image, that is, U data and V data are obtained, and reference values U ₀ and V _{0 that} are average values of the U data and V data in the reference image are calculated. The The reference values U ₀ and V ₀ are data indicating the color of the subject in the reference image F1, and indicate one feature of the reference image F1.
[0026]
In step 106, a comparison image in the same area as the reference image F1 is extracted based on an imaging signal obtained by the CCD 33 after a predetermined time (for example, 1/30 second) has elapsed since the previous imaging operation of the CCD 33. Then, U data and V data corresponding to each pixel of the comparison image are obtained, and comparison values Un and Vn which are average values of the U data and V data in the comparison image are calculated. The comparison values Un and Vn are data indicating the color of the subject in the comparison image and indicate one feature of the comparison image.
[0027]
In step 107, it is determined whether or not | Un−U ₀ | or | Vn−V ₀ | is greater than a predetermined value. When | Un−U ₀ | or | Vn−V ₀ | is equal to or smaller than a predetermined value, the process returns to Step 106. That is, by executing Steps 106 and 107, a comparison image is extracted at every elapse of a predetermined time, comparison values Un and Vn are calculated, and values of | Un−U ₀ | and | Vn−V ₀ | are determined.
[0028]
When it is determined in step 107 that | Un−U ₀ | or | Vn−V ₀ | is larger than a predetermined value, the process proceeds to step 108, and the recording operation of the photographed image is executed. In step 108, image data (that is, luminance data, U data, V data) constituting one screen is stored in the image memory 40 based on the imaging signal obtained from the CCD 33 by the execution of step 106 immediately before. In step 109, the image data is read from the image memory 40, compressed by the JPEG processing circuit 41, and recorded on the PC card 43. This completes the image recording routine.
[0029]
FIG. 5 shows an example of the temporal change of | Ui−U ₀ | and | Vi−V ₀ |. │Ui-U ₀ │ and │Vi-V ₀ │ is detected, for example, every 1/30 seconds as described above. Ui and Vi take values of 0 to 255, for example. In the example of FIG. 5, | Un-U ₀ | or | Vn-V ₀ | is a predetermined value (Tn seconds after the release switch is turned on). 16) is exceeded.
[0030]
The step 108 may be executed immediately after the determination in the step 107, but is executed after a predetermined time (for example, 0.1 second) elapses or after a predetermined number of images (for example, three images) are captured by the CCD 33. It may be. Thus, by executing the recording operation after a predetermined time elapses, it becomes possible to obtain a desired photograph at a more accurate timing.
[0031]
As described above, according to the present embodiment, the photographing operation is performed when the amount of change per unit time of the image in the central portion of the monitor screen exceeds a predetermined value. Therefore, for example, when shooting a moment when a person turns around, the reference image F1 mainly includes the back of the person and therefore contains a lot of hair color (black). In the comparison image, the skin color of the face is accompanied by the turning action. Appears. When the skin color ratio in the comparative image increases to some extent, the recording operation is performed from step 107 to step 108. Therefore, it is possible to reliably take a desired photograph even if the turning motion is fast.
[0032]
6 and 7 are flowcharts showing other examples of the image recording routine in the turning shot mode. In the example of FIG. 3, one monitor image that is a moving image displayed on the liquid crystal panel 46 is recorded as it is on the PC card 43, but in the examples of FIGS. 6 and 7, the electronic shutter of the CCD 33 is used together. Images with less blur can be recorded.
[0033]
The processing contents of steps 201 and 202 are the same as those of steps 101 and 102 in FIG. In step 203, an aperture value is calculated based on the photometric value during through, that is, while the moving image of the subject is being monitored. In step 204, the shutter speed when the aperture is opened is calculated based on the photometric value.
[0034]
In step 205, the aperture of the diaphragm 17 is adjusted to the diaphragm value calculated in step 203 under the control of the diaphragm drive circuit 32. The processing contents of steps 206 to 209 are the same as those of steps 104 to 107 in FIG.
[0035]
In step 210, the diaphragm 17 is driven to the open state. In step 211, the electronic shutter is controlled by the shutter speed calculated in step 204, and the CCD 33 is exposed. In step 212, the diaphragm 17 is completely closed, whereby the CCD 33 is completely shielded from light. In step 213, image data is stored in the image memory 40 based on the imaging signal obtained from the CCD 33 by executing step 211. The processing content of step 214 is the same as that of step 109 in FIG.
[0036]
Note that step 211 may be executed immediately after execution of step 210, or may be executed after a predetermined time has elapsed. Step 212 is for preventing leakage of light during the transfer operation of the CCD 33, and can be omitted.
[0037]
According to the image recording routines of FIGS. 6 and 7, since photography is performed with the aperture opened, that is, at a high shutter speed, a photograph with less blur can be obtained.
[0038]
Note that the reference image F1 is not limited to the central portion of the screen F0 to be photographed, and may be an upper portion of the center, or may be configured to be able to switch the position of the reference image F1. Further, the reference image F1 may be the entire screen F0.
[0039]
【The invention's effect】
As described above, according to the present invention, a desired photograph can be surely taken even when the subject moves quickly.
[Brief description of the drawings]
FIG. 1 is a perspective view of a digital camera according to an embodiment of the present invention as viewed from the rear.
FIG. 2 is a block diagram mainly showing an electrical configuration of the digital camera.
FIG. 3 is a flowchart of an image recording routine in a turning shot mode.
FIG. 4 is a diagram illustrating a position of a reference image on a screen to be photographed.
FIG. 5 is a diagram illustrating an example of temporal changes of | Ui−U ₀ | and | Vi−V ₀ |;
FIG. 6 is a first half portion of a flowchart showing another example of an image recording routine in a turning shot mode.
FIG. 7 is a second half of a flowchart showing another example of the image recording routine in the turning shot mode.
[Explanation of symbols]
31 System control circuit

Claims (7)

A reference image extracting means for extracting a reference image corresponding to at least a part of a screen to be photographed, and obtaining a reference value indicating a characteristic of the reference image;
Comparison image extraction means for extracting a comparison image in the same area as the reference image from a screen to be taken every predetermined time after the reference value is obtained, and obtaining a comparison value indicating the characteristics of the comparison image When,
A digital camera comprising: a recording operation control unit that executes a recording operation based on a result of comparing the reference value and the comparison value.   The digital camera according to claim 1, wherein the reference image and the comparison image are images of a central portion of the screen to be photographed.   The digital camera according to claim 1, wherein the reference value and the comparison value are data indicating a color of a subject.   The digital camera according to claim 3, wherein the reference value and the comparison value are average values of color difference data relating to pixels constituting the reference image and the comparison image, respectively. The reference value and the comparison value are average values of color difference data relating to the pixels constituting the reference image and the comparison image, respectively, and the recording operation control means has an absolute value of a difference between the reference value and the comparison value. 4. The digital camera according to claim 3, wherein a recording operation is executed when the value exceeds a predetermined value.   The digital camera according to claim 1, wherein the recording operation control unit executes a recording operation after a predetermined time has elapsed after obtaining a result of comparing the reference value and the comparison value.   The digital camera according to claim 1, wherein the recording operation control unit performs photographing and recording operations with the aperture set to an open state.

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