JP2007053447A - Imaging apparatus and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique of coding motion image data which can suppress deterioration in the image quality, without causing coding efficiency to deteriorate. <P>SOLUTION: When the kind of frame image that is to be subsequently coded is not an in-frame coding image during imaging of motion image data, changing of an imaging parameters, such as zoom, focus, exposure or white balance is inhibited. In this way, deterioration in correspondence relation between frames can be suppressed, and the deterioration in image quality can be suppressed without increasing the proportion of in-frame coded images in coding. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for encoding captured moving image data.

  Currently, imaging devices such as digital video cameras that can convert an analog image signal into a digital image signal and record and reproduce the image on a magnetic tape, an optical disk, or the like are in widespread use. Among these image pickup apparatuses, in particular, in an apparatus that records an image signal (data) on a disk medium such as a DVD-R, it is common to encode and record the image data using the MPEG method.

  In the encoding by the MPEG system, the information amount (data amount) of moving image data can be efficiently compressed by using motion compensation prediction encoding between frames. In the MPEG system, a still image of one frame is divided into blocks called macroblocks, each block is subjected to DCT (discrete cosine transform) processing and quantization processing, and then variable length coding is performed. A high compression rate can be obtained by combining the motion compensation prediction coding between the frames described above.

  Each frame of moving image data to be encoded is classified into three picture types of I, P, and B. An I picture is a frame that performs intraframe coding, and can be encoded and decoded independently without referring to information of other frames. In other words, motion compensation predictive coding between frames is not used in the I picture. Therefore, in general, an I picture requires a larger amount of code (data amount) than P and B pictures described below.

  The P picture performs so-called inter-frame prediction encoding, in which a difference from an image signal predicted with reference to an image signal of a past I or P picture is encoded (motion compensation prediction encoding). Therefore, the P picture can reduce the amount of code compared to the I picture.

  A B picture is a so-called bi-directional frame that encodes a difference from an image signal predicted with reference to an image signal of a future I or P picture in addition to a past I or P picture (motion compensation prediction encoding). Inter prediction encoding is performed. Therefore, the B picture can further reduce the code amount than the P picture.

  In such an encoding method, encoding is performed using correlation (difference) between frames, and therefore, when the correlation between frames is low and motion compensation is difficult, the image quality of the encoded image data is deteriorated. There was a problem.

As a method for solving such a problem, Patent Document 1 discloses a method for encoding image data by changing encoding characteristics based on control information of an imaging apparatus such as imaging start, stop, fade, zoom, and the like. Disclose. Further, Patent Document 2 optimizes the bit rate by determining the importance of the imaging scene and the imaging environment based on the control information of the imaging device such as shooting start, stop, lens drive, exposure, white balance, camera shake, and the like. A method of setting is disclosed.
JP-A-7-107466 JP 2002-369142 A

  However, in the conventional method described above, adjustment of encoding characteristics and bit rate is performed by inserting an I picture. Therefore, there is a problem in that the I picture increases and the encoding efficiency decreases when the correlation between frames decreases. there were.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a moving image data encoding technique that suppresses deterioration in image quality without reducing encoding efficiency.

  In order to solve the above problems, an imaging apparatus according to the present invention includes an encoding unit that encodes moving image data captured in accordance with imaging parameters in MPEG format, and a frame of the moving image data that the encoding unit is encoding. A determination unit that determines whether or not a type of a frame image to be encoded next to the image is an intra-frame encoded image; and a control unit that controls a change in the imaging parameter. When the type of the frame image by the determination unit is not an intra-frame encoded image, the change of the imaging parameter is prohibited.

  Also, the imaging method of the present invention includes an encoding step of encoding moving image data captured in accordance with an imaging parameter in MPEG format, and encoding the frame image of the moving image data being encoded by the encoding means. A determination step for determining whether the type of frame image to be performed is an intra-frame encoded image, and a control step for controlling change of the imaging parameter, wherein the control step includes the frame image obtained by the determination step. The change of the imaging parameter is prohibited when the type is not an intra-frame encoded image.

  Other features of the present invention will become more apparent from the accompanying drawings and the following description of the best mode for carrying out the invention.

  With the above configuration, according to the present invention, it is possible to provide a moving image data encoding technique that suppresses deterioration in image quality without reducing encoding efficiency.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[First Embodiment]
<Configuration of digital video camera 100>
FIG. 1 is a block diagram showing a configuration of a digital video camera 100 that can be used as an imaging apparatus of the present invention.

  The digital video camera 100 includes a lens 101, a diaphragm 102, and a CCD 103. The optical image incident from the lens 101 is imaged on the CCD 103 with the light amount adjusted by the diaphragm 102.

  The video light 104 is a light that can be turned on to irradiate auxiliary light when capturing a moving image.

  The CCD 103 performs photoelectric conversion for converting the formed optical image from an optical signal to an electrical signal, and sends the obtained electrical signal to the signal processing unit 105.

  The signal processing unit 105 performs signal processing such as luminance correction, white balance processing, and digital effect processing such as fading on the electrical signal sent from the CCD 103, and sends the signal to the encoding processing unit 106. The signal processing unit 105 can also perform signal processing on the electrical signal in a form suitable for display as image data on the display 107.

  The display 107 functions as an electronic viewfinder by displaying image data composed of electrical signals sent from the signal processing unit 105. It is also possible to display image data during image reproduction.

  The encoding processing unit 106 encodes the electric signal sent from the signal processing unit 105 into JPEG format for still image data and MPEG format for moving image data, and stores it on the magnetic tape 108 or the DVD medium 109. Record.

  The magnetic tape 108 is, for example, a DV cassette, and the DVD medium 109 is, for example, a DVD-R or a DVD-RAM. These may be any digital signals (data) as long as they can be recorded. For example, image data may be recorded in an HDD (hard disk drive).

  The control unit 110 is a microcomputer that controls the entire digital video camera 100. The control unit 110 includes a ROM (not shown) that holds a control program, an SRAM (not shown) that records settings (control information) of the digital video camera 100, and a DRAM (not shown) that is used as a temporary work area when the control program is executed. ) Etc. The control unit 110 controls the signal processing unit 105 and the encoding processing unit 106 by executing a control program, and controls a lens control unit 112 and the like described below.

  The operation unit 111 is an interface for a user to give an instruction to the digital video camera 100, and includes a power button (not shown), an imaging start button (not shown), and the like.

  The lens control unit 112 performs control such as focusing and zooming of the lens 101.

  The aperture control unit 113 performs exposure control by controlling the aperture 102 and also controlling the shutter speed.

  The CCD control unit 114 performs control such as charge accumulation and reading of the CCD 103.

  The video light control unit 115 controls the turning on / off of the video light 104 and the light emission amount.

<Appearance of digital video camera 100>
FIG. 2 is a perspective view showing the external appearance of the digital video camera 100. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  The microphone 201 is for recording sound during imaging.

  The viewfinder 202 allows the user to aim at the subject or confirm the subject by looking into it. The viewfinder 202 may be an optical viewfinder or an electronic viewfinder.

  The moving image trigger switch 203 is a push button, and the user can instruct the digital video camera 100 to start and end moving image capturing by operating the push button.

  The still image trigger switch 204 is a push button, and the user can instruct the digital video camera 100 to capture a still image by operating the push button.

  The mode dial 205 is a rotary switch, and includes, for example, a “playback mode” for playing back image data, a “camera mode” for shooting an object, and a “power-off mode” for turning off the power. The user can instruct the digital video camera 100 to change the mode by operating the mode dial 205.

  The operation panel 206 is a panel that collects buttons for the user to instruct the digital video camera 100 to perform operations other than the operations described above, for example, selection or deletion of image data.

  The moving image trigger switch 203 to the operation panel 206 are included in the operation unit 111 of FIG.

  As described with reference to FIG. 1, the display 107 can be opened and closed with respect to the digital video camera 100, and can also be rotated in the horizontal direction while being opened from the digital video camera 100.

  The speaker 207 is for outputting sound when reproducing image data.

  The battery 208 is for supplying power to the digital video camera 100 and is detachable from the digital video camera 100.

<Timing of control of lens 101 etc.>
In the present embodiment, the control unit 110 adjusts the timing for controlling the lens 101 and the like via the lens control unit 112 and the like of the digital video camera 100 in order to suppress the image quality deterioration of the moving image data. The control unit 110 changes the zoom, focus, exposure, white balance, and the like during imaging by controlling the lens 101 and the like. Hereinafter, zoom, focus, exposure, white balance, and the like that can be changed by controlling the lens 101 are collectively referred to as “imaging parameters”.

  For example, when the imaging parameter (in this example, focus) is changed when the subject has moved far away, image data to be encoded by the encoding processing unit 106 may change significantly. Therefore, as described above, the frame correlation becomes low and the image quality may be deteriorated.

  Therefore, in the present embodiment, the timing at which the imaging parameter is changed (timing for controlling the lens 101 and the like) is adjusted based on information received from the encoding processing unit 106 by the control unit 110.

  FIG. 3 is a diagram schematically illustrating the timing of the imaging parameter changing process in the present embodiment. In FIG. 3, rectangles with I, P, and B indicate frames of I picture, P picture, and B picture of moving image data. “T” indicates a time axis, and the newer the frame is to the right. “GOP” is an abbreviation for “Group of Pictures”, and indicates a basic unit in encoding of the MPEG system. The letters “parameter change” and the arrow above it indicate that the imaging parameter is changed at the timing indicated by the arrow.

  Note that a GOP includes at least one I picture, and in the present embodiment, the top of the GOP is an I picture.

  As shown in FIG. 3, in this embodiment, the imaging parameter is changed immediately before the I picture. This is because an I picture does not perform inter-frame prediction at the time of encoding, and therefore, even if a decrease in frame correlation due to a change in imaging parameters occurs immediately before the I picture, it does not lead to deterioration in image quality.

  In the present embodiment, it is assumed that there is no I picture other than the head of the GOP. However, in the MPEG standard, an I picture may be used in the middle of the GOP. Therefore, the imaging parameters may be changed not only in the GOP break (final frame) as shown in FIG. 3 but also in the middle of the GOP as long as it is between the I picture and the previous picture. In the following description, what is expressed as “GOP breaks” may be read as “between an I picture and the previous picture”.

  FIG. 4 is a flowchart showing in detail the flow of the imaging parameter changing process outlined with reference to FIG. When the moving image trigger switch 203 is pressed while the digital video camera 100 is powered on, the processing of this flowchart is started.

  In step S401, the control unit 110 reads an initial value of the imaging parameter from an unillustrated SRAM. Next, the control unit 110 sets the read imaging parameters in the signal processing unit 105 and the lens control unit 112 to the video light control unit 115. Thereby, initial values of imaging parameters for controlling zoom, exposure, white balance, video light, digital effect, and the like are determined.

  In step S <b> 402, the encoding processing unit 106 encodes the electric signal sent from the signal processing unit 105 in the MPEG format and records it on the magnetic tape 108 or the DVD medium 109. This process is a moving image capturing (recording) process. Although not shown, when the control unit 110 receives an imaging end instruction from the operation unit 111, the process of this flowchart ends.

  In step S403, the control unit 110 acquires information indicating which frame in the current GOP is encoded from the encoding processing unit 106, and determines whether the currently encoded frame is a break in the GOP. If the currently encoded frame is not a GOP break, the process returns to step S402 without changing the imaging parameters. This is because if the imaging parameter is changed during the GOP, the image quality may be deteriorated due to the accompanying decrease in the frame correlation. In other words, the control unit 110 prohibits changing the imaging parameter in the middle of the GOP, and performs imaging processing with the imaging parameter that remains unchanged until the GOP breaks, for example, even if focus tracking is necessary. In this case, it is impossible to deny the possibility that the subject remains out of focus and adversely affects image quality. However, if the imaging parameters are changed in the middle of the GOP and the focus is adjusted again, there arises a problem of image quality deterioration due to a decrease in frame correlation. In this embodiment, image quality deterioration due to a decrease in frame correlation is more emphasized, and the control unit 110 does not change the imaging parameters during the GOP.

  If the control unit 110 receives an instruction to change the zoom from the operation unit 111 or the aperture needs to be changed due to the change in the brightness of the subject, the corresponding imaging parameter is changed by a DRAM (not shown). Memorize temporarily.

  On the other hand, if the currently encoded frame is a GOP break, since it is unlikely that a decrease in frame correlation due to the imaging parameter change will cause image quality deterioration, the process proceeds to step S404, and the imaging parameter change is performed as follows. Do.

  In step S404, the control unit 110 determines whether it is necessary to drive the lens 101 by changing imaging parameters for focus change or zoom change. Here, it is determined whether there is a change in the imaging parameter stored in the DRAM (not shown) as described above in addition to the change in the imaging parameter based on the change of the subject or the instruction from the operation unit 111. Hereinafter, in each step in which determination is performed in this flowchart, it is similarly determined whether there is a change in the imaging parameter stored in the DRAM (not shown). If the imaging parameter needs to be changed, the process proceeds to step S405, and if not necessary, the process proceeds to step S406.

  In step S <b> 405, the control unit 110 sets (changes) imaging parameters corresponding to the control of the lens 101 in the lens control unit 112, and the lens control unit 112 performs control such as focus change and zoom change of the lens 101.

  In step S406, the control unit 110 determines whether it is necessary to change the imaging parameter for changing the exposure. If the imaging parameter needs to be changed, the process proceeds to step S407, and if not necessary, the process proceeds to step S408.

  In step S407, the control unit 110 sets (changes) imaging parameters corresponding to the control of the diaphragm 102 in the diaphragm control unit 113, and the diaphragm control unit 113 narrows or opens the diaphragm 102.

  In step S408, the control unit 110 determines whether it is necessary to change the imaging parameter in order to change the white balance of the image data. If the imaging parameter needs to be changed, the process proceeds to step S409, and if not necessary, the process proceeds to step S410.

  In step S409, the control unit 110 sets (changes) an imaging parameter corresponding to control of white balance processing in the signal processing unit 105. Thereafter, the signal processing unit 105 performs white balance processing on the electrical signal sent from the CCD 103 based on the newly set parameters.

  In step S410, the control unit 110 determines whether the imaging parameter needs to be changed in order to turn on / off the video light 104, change the light emission amount, and the like. If the imaging parameter needs to be changed, the process proceeds to step S411, and if not necessary, the process proceeds to step S412.

  In step S411, the control unit 110 sets (changes) imaging parameters corresponding to the control of the video light 104 in the video light control unit 115, and the video light control unit 115 turns on / off the video light 104, changes the light emission amount, and the like. I do.

  In step S412, the control unit 110 determines whether it is necessary to change imaging parameters in order to apply digital effects such as fading to the image data. If the imaging parameter needs to be changed, the process proceeds to step S413, and if not necessary, the process returns to step S402.

  In step S413, the control unit 110 sets (changes) the imaging parameter corresponding to the control of the digital effect in the signal processing unit 105. Thereafter, the signal processing unit 105 applies a digital effect to the electrical signal sent from the CCD 103 based on the newly set parameters. Next, the process returns to step S402.

  Thus, the digital video camera 100 repeats the above processing until receiving an imaging end instruction.

  Note that the types of imaging parameters that are changed in steps S404 to S413 are merely examples. For example, it may be determined whether imaging parameters relating to camera shake correction or the like need to be changed. That is, any imaging parameter that can reduce frame correlation and cause image quality degradation may be determined.

  In addition, the control unit 110 needs to change the imaging parameter within a limited time such as a GOP break, and when the change is not completed within this time, the process returns to step S402 from any of steps S404 to S413. . At this time, the control unit 110 stores the contents of the change that has not been completed in the DRAM (not shown), and performs the change at the next GOP break.

  Moreover, although the process of step S404 thru | or step S413 was demonstrated in order according to the time series in this embodiment, in practice, you may perform in arbitrary orders and may be performed in parallel.

<Summary of First Embodiment>
As described above, according to the present embodiment, the digital video camera 100 changes the imaging parameter only when the currently encoded frame is a GOP break. Further, when it is necessary to change the imaging parameter other than the GOP break, the contents of the change are temporarily stored in a DRAM (not shown), and the actual change is performed at the GOP break.

  Thereby, it is possible to suppress a decrease in frame correlation in the GOP in MPEG encoding, and it is possible to suppress deterioration in image quality. Further, since the ratio of I pictures is not increased, it is possible to suppress a decrease in encoding efficiency and to suppress an increase in code amount (data amount).

[Second Embodiment]
In the first embodiment, the digital video camera 100 in FIG. 1 changes the imaging parameter only when the currently encoded frame is a GOP break. In the second embodiment, a mode in which the digital video camera 100 changes (allows) the imaging parameter even during the GOP when the change amount of the imaging parameter is smaller than a predetermined threshold value will be described.

  According to the present embodiment, if the change amount of the imaging parameter is small, the imaging parameter is changed even during the GOP. Therefore, it is possible to perform imaging with an imaging parameter more suitable for the imaging environment. On the other hand, if the change amount of the imaging parameter is small, the decrease in the frame correlation is relatively small, and the deterioration of the image quality is not so much a problem.

  In the present embodiment, the configuration of the digital video camera 100 may be the same as that of the first embodiment, and the description thereof is omitted.

  FIG. 5 is a flowchart showing in detail the flow of imaging parameter change processing in the second embodiment. In this flowchart, steps that perform the same processing as in FIG. As in the first embodiment, when the digital video camera 100 is turned on and the moving image trigger switch 203 in FIG. 2 is pressed, the processing of this flowchart is started. Although not shown, when the control unit 110 receives an imaging end instruction from the operation unit 111 as in the first embodiment, the process of this flowchart ends.

  In step S501, the control unit 110 acquires information indicating which frame in the current GOP is encoded from the encoding processing unit 106, and determines whether the currently encoded frame is a GOP break (final frame). Determine. If the currently encoded frame is not a GOP break, the process advances to step S502, unlike the first embodiment.

  On the other hand, if the currently encoded frame is a GOP break, since it is unlikely that a decrease in frame correlation due to the imaging parameter change will cause image quality degradation, the process proceeds to step S404, and imaging is performed in the same manner as in the first embodiment. Change the parameters.

  In step S502 to step S507, since there is a possibility that image quality deterioration may be caused by changing the imaging parameter, only the imaging parameter that needs to be controlled in a short cycle is changed under a certain condition. The imaging parameter that needs to be controlled in a short cycle for changing the imaging parameter is an imaging parameter related to the control of the lens 101 and the diaphragm 102, for example. This is because, for example, if the focus is shifted, there is a high possibility that the image quality is adversely affected. Therefore, it is preferable to adjust the focus as much as possible even during the GOP.

  In step S502, the control unit 110 determines whether it is necessary to drive the lens 101 by changing imaging parameters for focus change or zoom change. Here, it is determined whether there is a change in the imaging parameter stored in the DRAM (not shown) of the control unit 110 as described above in addition to the change in the imaging parameter based on the change of the subject or the instruction from the operation unit 111. Hereinafter, in each step in which determination is performed in this flowchart, it is similarly determined whether there is a change in the imaging parameter stored in the DRAM (not shown). If the imaging parameter needs to be changed, the process proceeds to step S503, and if not necessary, the process proceeds to step S505.

  In step S503, the control unit 110 determines whether the change amount of the imaging parameter is equal to or less than a predetermined threshold value. The predetermined threshold is recorded in an SRAM (not shown) when the digital video camera 100 is manufactured. In addition, the user may be able to change the threshold value via the operation unit 111. If the change amount of the imaging parameter is not less than or equal to the predetermined threshold value, the frame correlation may be greatly reduced if the imaging parameter is changed. Therefore, the process proceeds to step S505 without changing the imaging parameter. In this case, the corresponding imaging parameter change is temporarily stored in a DRAM (not shown) of the control unit 110. If the change amount of the imaging parameter is equal to or smaller than the predetermined threshold value, the process proceeds to step S504.

  In step S504, the control unit 110 sets (changes) an imaging parameter corresponding to the control of the lens 101 in the lens control unit 112, and the lens control unit 112 performs control such as a focus change or a zoom change of the lens 101.

  In step S505, the control unit 110 determines whether it is necessary to change the imaging parameter for changing the exposure. If the imaging parameter needs to be changed, the process proceeds to step S506, and if not necessary, the process returns to step S402.

  In step S506, the control unit 110 determines whether the change amount of the imaging parameter is equal to or less than a predetermined threshold value. If the change amount of the imaging parameter is not less than or equal to the predetermined threshold value, the frame correlation may be greatly reduced when the imaging parameter is changed. Therefore, the process returns to step S402 without changing the imaging parameter. In this case, the corresponding imaging parameter change is temporarily stored in a DRAM (not shown) of the control unit 110. If the change amount of the imaging parameter is equal to or smaller than the predetermined threshold value, the process proceeds to step S507.

  In step S507, the control unit 110 sets (changes) imaging parameters corresponding to the control of the diaphragm 102 in the diaphragm control unit 113, and the diaphragm control unit 113 narrows or opens the diaphragm 102. Next, the process returns to step S402.

  Thus, the digital video camera 100 repeats the above processing until receiving an imaging end instruction.

  Note that the types of imaging parameters that are changed in steps S502 to S507 are merely examples, and if it is desired to perform imaging parameter change control in a short cycle, it is determined whether the imaging parameters related to white balance processing or the like need to be changed. May be. That is, any imaging parameter that can reduce frame correlation and cause image quality degradation may be determined. Imaging parameters that are not subject to determination, that is, imaging parameters that are not changed during the GOP can be set by setting the threshold value to 0, for example.

  Moreover, although the process of step S502 thru | or step S507 demonstrated in order according to the time series in this embodiment, in practice, you may perform in arbitrary orders and may be performed in parallel.

<Summary of Second Embodiment>
As described above, according to the present embodiment, when the change amount of the imaging parameter is smaller than the predetermined threshold, the digital video camera 100 changes (allows) the imaging parameter even during the GOP. . When the change amount of the imaging parameter is larger than a predetermined threshold value, the contents of the change are temporarily stored in a DRAM (not shown), and the actual change is performed at the GOP break.

  Thus, in addition to the advantages of the first embodiment, if the change amount of the imaging parameter is small, the imaging parameter is changed even during the GOP, so that it is possible to perform imaging with an imaging parameter more suitable for the imaging environment. On the other hand, if the change amount of the imaging parameter is small, the decrease in the frame correlation is relatively small, and the deterioration of the image quality is not so much a problem.

[Third Embodiment]
In the first and second embodiments, the change of the imaging parameter at the time of moving image imaging has been described. In the third embodiment, a description will be given of how to change imaging parameters when capturing a still image when capturing a moving image.

  Still image capturing often involves flash emission, which can change the imaging environment and cause a reduction in frame correlation. Therefore, this embodiment has a significance of suppressing deterioration in image quality of moving image data when still image capturing is performed during moving image capturing.

<Configuration of digital video camera 100>
FIG. 6 is a block diagram showing the configuration of the digital video camera 100 in the present embodiment. Except for the addition of the strobe 601, the memory card 602, and the strobe control unit 603, the second embodiment is the same as the first embodiment (see FIG. 1).

  The strobe 601 is for use as a flash when capturing a still image.

  The memory card 602 is a storage medium for recording, as still image data, an electric signal encoded by the encoding processing unit 106 from the signal processing unit 105 into a JPEG format. Still image data may be recorded on the magnetic tape 108 or the DVD medium 109.

  The strobe control unit 603 controls the amount of light emitted and the light emission timing of the strobe 601 in accordance with instructions from the control unit 110.

<Timing of control of lens 101 etc.>
FIG. 7 is a flowchart showing in detail the flow of imaging parameter change processing when a still image is captured during moving image capturing. Unlike the first embodiment (FIG. 4), this flowchart starts when the digital video camera 100 is powered on.

  In step S701, the control unit 110 reads an initial value of the imaging parameter from an unillustrated SRAM. Next, the control unit 110 sets the read imaging parameters in the signal processing unit 105 and the lens control unit 112 to the video light control unit 115. Thereby, initial values of imaging parameters for controlling zoom, exposure, white balance, video light, digital effect, and the like are determined.

  In step S <b> 702, the control unit 110 determines whether a still image capturing instruction is received from the still image trigger switch 204 (FIG. 2) of the operation unit 111. When a still image capturing instruction is received, the process proceeds to step S703. If no still image capturing instruction is received, the process waits in step S702 until it is received.

  Although not shown, when the control unit 110 receives a power-off instruction from the operation unit 111, the processing of this flowchart ends. When the control unit 110 receives a moving image capturing instruction from the moving image trigger switch 203 (FIG. 2) of the operation unit 111, the digital video camera 100 starts moving image capturing processing. During moving image capturing, the encoding processing unit 106 encodes the electric signal sent from the signal processing unit 105 in the MPEG format and records it on the magnetic tape 108 or the DVD medium 109.

  In step S703, the control unit 110 determines whether the strobe 601 needs to emit light. The determination here is performed, for example, by receiving the brightness of the subject or the imaging environment from a brightness sensor (not shown). If the flash 601 is not required to emit light, the imaging environment does not change due to still image capturing, and thus the process proceeds to step S707 to perform still image capturing processing. At this time, if a moving image is being captured and it is necessary to change the imaging parameter due to factors other than still image capturing, the imaging parameter changing process is performed in the same manner as in the first embodiment. If the strobe 601 needs to emit light, the process proceeds to step S704.

  In step S704, the control unit 110 determines whether the digital video camera 100 is capturing a moving image. If the moving image is not being captured, it is not necessary to consider the change of the imaging parameter, and the process proceeds to step S706. If a moving image is being captured, the process proceeds to step S705.

  In step S705, the control unit 110 acquires information indicating which frame in the current GOP is encoded from the encoding processing unit 106, and whether or not the currently encoded frame is a GOP break (final frame). Determine. If the currently encoded frame is not a GOP break, the process returns to step S704. This is because if the strobe 601 emits light in the middle of a GOP, the imaging environment (specifically, the luminance of the subject, etc.) changes, and the image quality may deteriorate due to the accompanying decrease in frame correlation. Therefore, the still image capturing process is delayed until the frame currently encoded becomes a GOP break. If the currently encoded frame is a GOP break, the process advances to step S706.

  In step S706, the control unit 110 emits the strobe 601 via the strobe control unit 603, and the process proceeds to step S707.

  In step S <b> 707, the encoding processing unit 106 encodes the electrical signal sent from the signal processing unit 105 in the JPEG format and records it in the memory card 602. Next, the process returns to step S702 to wait for the next still image capturing instruction.

<Summary of Third Embodiment>
As described above, according to the present embodiment, when performing still image capturing processing that requires the flash 601 to emit light during moving image capturing, the control unit 110 waits until a GOP break and performs still image capturing processing.

  As a result, it is possible to suppress deterioration in the image quality of the moving image data when still image capturing is performed during moving image capturing.

[Other Embodiments]
The processing of each embodiment described above provides a system or apparatus with a storage medium storing software program codes embodying each function, and the system or apparatus computer (or CPU or MPU) stores the storage medium. It can also be realized by reading and executing the program code stored in the. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM Etc. can be used.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. Includes the case where the functions of the above-described embodiments are realized by performing part or all of the actual processing.

  Furthermore, after the program code read from the storage medium is written to the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, the function is based on the instruction of the program code. This includes a case where a CPU or the like provided in an expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

1 is a block diagram showing a configuration of a digital video camera 100 that can be used as an imaging apparatus of the present invention. 1 is a perspective view showing an external appearance of a digital video camera 100. FIG. It is a figure which illustrates schematically the timing of the imaging parameter change process in 1st Embodiment. 4 is a flowchart illustrating in detail a flow of imaging parameter change processing in the first embodiment. It is a flowchart which shows the flow of the imaging parameter change process in 2nd Embodiment in detail. It is a block diagram which shows the structure of the digital video camera 100 in 3rd Embodiment. It is a flowchart which shows in detail the flow of an imaging parameter change process in the case of imaging a still image at the time of moving image imaging.

Explanation of symbols

100 Digital Video Camera 110 Control Unit

Claims (8)

Encoding means for encoding moving image data captured in accordance with imaging parameters in MPEG format;
A determination unit that determines whether or not a type of a frame image to be encoded next to a frame image of the moving image data being encoded by the encoding unit is an intra-frame encoded image;
Control means for controlling the change of the imaging parameter;
With
The control unit prohibits the change of the imaging parameter when the type of the frame image by the determination unit is not an intra-frame encoded image.   The control means permits the change of the imaging parameter when the change amount of the imaging parameter is a predetermined threshold or less even when the type of the frame image by the determination means is not an intra-frame encoded image. The imaging apparatus according to claim 1. The encoding means encodes the first frame image of the GOP as an intra-frame encoded image,
The determination means determines whether the type of the next frame image to be encoded is an intra-frame encoded image depending on whether the frame image of the image data being encoded by the encoding unit is the last frame image of the GOP. It is determined whether there exists. The imaging device of Claim 1 or 2 characterized by the above-mentioned. further,
A still image capturing means for capturing still image data;
Auxiliary light emitting means for emitting auxiliary light;
Auxiliary light control means for controlling whether to emit the auxiliary light when the still image data is captured by the still image capturing means;
Moving image capturing determination means for determining whether or not moving image data is being captured;
The moving image imaging determination means determines that the moving image data is being captured, the auxiliary light control means controls to emit the auxiliary light, and the type of the frame image by the determination means is A delay means for delaying imaging of the still image data by the still image imaging means until the type of the frame image by the determination means becomes an intra-frame encoded image when it is not an intra-frame encoded image;
The imaging apparatus according to any one of claims 1 to 3, further comprising:   5. The imaging parameter according to claim 1, wherein the imaging parameter is a parameter related to control of at least one of zoom, focus, exposure, white balance, video light, strobe, and digital effect. Imaging device. An encoding process for encoding moving image data captured in accordance with imaging parameters in MPEG format;
A determination step of determining whether a type of a frame image to be encoded next to a frame image of the moving image data being encoded by the encoding unit is an intra-frame encoded image;
A control step for controlling the change of the imaging parameter;
With
The control method prohibits the change of the imaging parameter when the type of the frame image determined in the determination step is not an intra-frame encoded image. A program code for executing an encoding process in which a computer encodes moving image data captured in accordance with imaging parameters in MPEG format;
Program code for executing a determination step for determining whether or not a type of a frame image to be encoded next to a frame image of the moving image data being encoded by the encoding means is an intra-frame encoded image When,
A computer code for executing a control process for controlling the change of the imaging parameter;
With
The computer program characterized in that the control step prohibits the change of the imaging parameter when the type of the frame image in the determination step is not an intra-frame encoded image.   A computer-readable storage medium storing the computer program according to claim 7.

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