JP4547877B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus. Specifically, when an image signal of a variable frame rate captured image is supplied to an external device, the input frame rate of the external device is detected, and the image signal of the variable frame rate captured image is converted to the detected input frame rate. Output.

  In conventional movie production and the like, shooting is performed by varying the shooting speed of a film camera, that is, the number of frames per second, so that a special video effect can be obtained. For example, if shooting is performed at a speed higher than the normal speed and playback is performed at the normal speed, the playback image becomes a slow playback image. For this reason, it is possible to observe easily and in detail a high-speed operation like when a water droplet falls on the water surface. If shooting is performed at a lower speed than normal speed and playback is performed at a normal speed, a high-speed playback image is obtained. For this reason, it is possible to enhance the sense of speed in a fighting scene, a car chase scene, etc., and to present an image with a high sense of reality.

  Also, in television program production, etc., digitization such as program shooting, editing, and transmission has been attempted, but in the production of movies, etc. due to the increase in image quality and the reduction in equipment prices accompanying the advancement of digital technology. It has been planned.

  Here, when imaging is performed using an imaging device (video camera) by digitization such as television program production or movie production, special video effects such as high-speed playback and slow playback can be easily obtained. As described above, the imaging apparatus disclosed in Patent Document 1 that can change the frame rate is used. By using this imaging device to capture an image with a frame rate lower than the predetermined frame rate and reproducing the captured image at a predetermined frame rate, a high-speed playback image can be easily obtained. Further, if the image is taken at a high frame rate and the captured image is reproduced at a predetermined frame rate, a slow reproduction image can be easily obtained.

JP 2000-125210 A

  By the way, when an image display device such as an electronic viewfinder or a monitor device is connected to the imaging device as an external device and the image being captured is confirmed by the display image of the image display device, in order to facilitate the confirmation of the image It is desirable that the displayed image has high image quality. However, if the signal output from the imaging device is fixed to a predetermined frame rate, even if an image display device capable of displaying an image at a frame rate higher than this frame rate is used, the display of the image display device The performance is not utilized effectively, and the image being captured cannot be displayed with high image quality.

  Therefore, the present invention provides an imaging apparatus that can display an image being captured with high image quality.

In order to solve the above problems and achieve the object of the present invention, an imaging apparatus of the present invention has an image signal generating means for generating an image signal of a variable-speed frame rate captured image and an input frame rate of an external device connected thereto Frame rate detection means for detecting, and first frame rate conversion processing means for converting the image signal of the variable frame rate captured image into the input frame rate detected by the frame rate detection means. In addition, the first frame rate conversion processing means selects the image signal by selecting the number of frames to be added according to the input frame rate from the connected external device when performing the frame addition process of the image signal from the imaging device. Additional frame number selection means for changing the frame rate.

When the external device is compatible with a plurality of input frame rates, the frame rate detection means detects the maximum frame rate of the external device, and the first frame rate conversion processing means detects the variable frame rate. The image signal of the captured image is converted into the maximum value of the input frame rate detected by the frame rate detection means, and the image signal after the frame rate conversion is output as a monitor image signal. When the input frame rate is not detected by the frame rate detection means, an image signal that has not been subjected to frame rate conversion by the first frame rate conversion processing means is output as a main line image signal.

As a preferred embodiment of the present invention, a second frame rate conversion processing unit is provided, and an image signal generated by the second frame rate conversion processing unit is output as a main line image signal and generated by the frame rate conversion unit. image signal is Ru generated as monitor image signal. Et al is, the image signal generation means, image signals of variable frame-rate picked-up image is generated by the input frame rate than the frame rate.

  According to this invention, the image signal generating means for generating the image signal of the variable-speed frame rate captured image, the frame rate detecting means for detecting the input frame rate of the connected external device, and the image of the variable-speed frame rate captured image Frame rate conversion processing means for converting the signal into an input frame rate detected by the frame rate detection means and outputting the converted signal to an external device is provided. For this reason, if an image display device capable of displaying an image at a high frame rate is used as an external device, the captured image can be displayed with high image quality, and the image being captured can be easily confirmed. .

  Further, the frame rate conversion processing means outputs the image signal after the frame rate conversion as a monitor image signal, and when the input frame rate is not detected by the frame rate detection means, the frame rate conversion is not performed. An image signal is output as a main line image signal. For this reason, a main line picture signal or a monitor picture signal can be outputted according to the connected external device.

  The image signal generated by the image signal generation means is output as a main line image signal, and the image signal whose frame rate is converted by the frame rate conversion processing means is output as a monitor image signal. Therefore, the monitor image can be displayed with high image quality and the main line image can be output separately.

  In addition, second frame rate conversion processing means for converting the frame rate of the image signal generated by the image signal generating means is provided, and the image signal whose frame rate is converted by the second frame rate conversion processing means is the main line image signal. And an image signal whose frame rate has been converted by the frame rate conversion processing means is output as a monitor image signal. Therefore, the main line image signal and the monitor image signal can be generated at a desired frame rate regardless of the frame rate of the image signal generated by the image signal generation means.

Furthermore, since the image signal generated by the image signal generation means has a frame rate equal to or higher than the input frame rate, the frame rate is adjusted by repeating the same frame image when the frame rate conversion of the image signal is performed. There is nothing. Further, since the frame rate conversion of the image signal is performed so that the maximum value of the input frame rate of the external device, an image can be displayed in imaging with high image quality by effectively using the display performance of the external device.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a first configuration of the imaging apparatus. The light incident through the imaging lens and the iris is incident on the imaging unit 21 that constitutes the image signal generation unit 20 of the imaging device 10, and a subject image is formed on the imaging surface of the imaging element. The imaging element generates an imaging charge of the subject image by photoelectric conversion, reads the imaging charge based on the drive control signal RC supplied from the drive unit 22, converts the read imaging charge into a voltage signal, and converts the imaging signal Spa. To the imaging signal processing unit 23. In addition, when the image signal of the variable-speed frame rate captured image is generated by changing the frame rate of the captured image during imaging, the timing of reading the imaged charge is controlled by the drive control signal RC, and the frame rate of the imaged signal Spa is determined. Is made to correspond to the frame rate of the variable-speed frame rate captured image.

  The drive unit 22 generates a drive control signal RC based on a control signal CT supplied from the control unit 50 described later, and supplies the drive control signal RC to the imaging unit 21.

  The imaging signal processing unit 23 amplifies the imaging signal Spa and then removes noise components. Further, after the image signal from which noise has been removed is converted into a digital signal, feedback clamp processing, flare correction, correction processing for defects in the image sensor, process processing, and the like are performed to generate an image signal DVa. The image signal DVa is supplied to the frame rate conversion processing unit 30.

  The frame rate conversion processing unit 30 performs a frame rate conversion process based on a frame rate detection signal FDT from a frame rate detection unit 40 to be described later, and inputs the image signal DVa to the input frame rate of the external device 100 connected to the imaging device 10. And output to the external device 100 as an image signal DVb.

  The frame rate detection unit 40 detects the input frame rate of the connected external device 100 and supplies it to the frame rate detection signal FDT frame rate conversion processing unit 30 indicating the detected input frame rate. For example, the input frame rate is detected by communicating with the external device 100 to obtain information on the input frame rate from the external device 100. Further, input frame rate information of connectable external devices is stored in advance, it is determined which external device is connected, and input frame rate information corresponding to the determined external device is read and used. In addition, a signal indicating the input frame rate of the external device 100 is input by a user from a user interface unit 51 described later, and the input signal is supplied to the frame rate conversion processing unit 30 as a frame rate detection signal FDT. it can. Further, when the external device 100 is compatible with a plurality of input frame rates, the frame rate detection unit 40 notifies the frame rate conversion processing unit 30 of the input frame rate with the highest frame rate by the frame rate detection signal FDT. .

  A user interface unit 51 is connected to the control unit 50. When an operation signal PS corresponding to a user operation is supplied via the user interface unit 51, the control unit 50 generates a control signal CT based on the operation signal PS and supplies the control signal CT to the image signal generation unit 20. The imaging device 10 is operated according to a user operation. Further, when the frame rate of the variable-speed frame rate captured image is varied by the operation signal PS, the frame rate of the imaging signal Spa generated by the imaging unit 21 based on the control signal CT is changed to the frame of the variable-speed frame rate captured image. Variable according to the rate.

  FIG. 2 shows an example of the configuration of the frame rate conversion processing unit 30. The frame rate conversion processing unit 30 sequentially writes the supplied image signal DVa in, for example, three RAMs (Random Access Memory) 31-a to 31-c in units of frames. Further, the image signal written in the RAM is read while sequentially selecting the RAM according to the input frame rate of the external device 100, and the image signal DVa is converted into the image signal DVb of the input frame rate and output.

  Although not shown, the writing control unit 32 is based on the control signal CT from the control unit 50 or uses the synchronization signal SYa of the image signal DVa to select a RAM for writing the image signal DVa. A write control signal CKW for writing the SEW and the image signal DVa into the RAM is generated. This selection signal SEW is supplied to the signal selector 33. Further, the writing control signal CKW is supplied to a RAM that writes the image signal DVa. Further, the write control unit 32 generates a write information signal MIF indicating the write state of the image signal DVa in each RAM and supplies it to the read control unit 34.

  The signal selector 33 supplies the image signal DVa to the RAM selected by the selection signal SEW, and the selected RAM writes the image signal DVa based on the write control signal CKW.

  The read control unit 34 generates a read control signal CKR based on the frame rate detection signal FDT. The read control signal CKR is a signal for reading an image signal from the RAM at the input frame rate of the external device 100. Further, a selection signal SER for selecting a RAM from which an image signal is read is generated based on the frame rate detection signal FDT and the write information signal MIF. The selection signal SER is supplied to the signal selector 35. Further, the read control signal CKR is supplied to the RAM for reading the image signal or each RAM.

  The RAM supplied with the read control signal CKR reads the stored image signal based on the read control signal CKR and supplies it to the signal selector 35. The signal selector 35 selects the image signal read from the RAM selected by the selection signal SER and outputs it as the image signal DVb.

  Here, the reading of the image signal from the RAM is performed by determining the RAM in which the writing of the image signal has been completed last based on the writing information signal MIF, and reading the image signal next to the determined RAM. The selection signal SER is generated so as to select as follows. Further, when an image signal for one frame is read from the RAM, if it is detected by the write information signal MIF that the writing of the image signal of the next frame is not completed, the RAM for reading the image signal is not changed. Assume that image signals of the same frame are read out. By controlling the reading of the image signal in this way, when the frame rate of the image signal DVa is set higher than the input frame rate, frame thinning according to the input frame rate is performed on the image signal DVa. Thus, the image signal DVb having the input frame rate can be generated. When the frame rate of the image signal DVa is set lower than the input frame rate, a frame is added by repeating the image signal DVa in units of frames, and the image signal DVb having the input frame rate can be generated.

  Thus, since the image signal DVb corresponding to the input frame rate of the external device 100 is output from the imaging device 10, when an image display device capable of displaying an image at a high frame rate is connected, The captured image can be displayed with high image quality, and the image being captured can be easily confirmed.

  When the external device 100 is compatible with a plurality of input frame rates, the highest input frame rate is indicated by the frame rate detection signal FDT. For this reason, the image signal DVa is converted to the input frame rate with the highest frame rate and output as the image signal DVb. Therefore, the image being captured can be displayed by effectively utilizing the display performance of the external device 100.

  Further, when the frame rate detection signal FDT is not supplied from the frame rate detection unit 40, the frame rate conversion processing unit 30 outputs the image signal DVb as the image signal DVb without converting the frame rate. According to this configuration, the image signal DVb having the input frame rate or the image signal DVb not subjected to frame rate conversion is output according to the connected external device 100, and the image is displayed as the external device 100 as described above. When the apparatus is connected, the captured image can be displayed with high image quality by using the image signal DVb of the input frame rate as the monitor image signal. In addition, a signal recording device using an optical disk, a magnetic disk, or the like is connected as the external device 100, and the frame rate is not converted so that the frame rate detection signal FDT is not supplied to the frame rate conversion processing unit 30. If the image signal DVb is used as the main line image signal, the image signal DVa of the variable-speed frame rate captured image generated by the image signal generation unit 20 can be recorded in the order of frames.

  By the way, when the imaging frame rate is varied and the image signal of the captured image is generated as in the above-described embodiment, the number of frames of the generated image signal is reduced when the frame rate of the captured image is decreased. Become. At this time, an image displayed on an image display device such as an electronic viewfinder is displayed repeatedly in the same frame by frame rate conversion, and the update interval of the captured image becomes longer. Therefore, even if an image display device capable of displaying an image at a high frame rate is used, the image being captured cannot be displayed with high image quality while being updated at a high frame rate. In addition, since the same frame image is repeatedly displayed and the update interval of the captured image is long, it is impossible to capture the subject so that the subject position is the desired position of the captured image when the subject moves quickly. End up. Therefore, a frame rate conversion processing unit 60 serving as a second frame rate conversion processing unit is provided so that not only the frame rate control of the imaging signal Spa but also the frame rate conversion of the image signal is performed according to the frame rate of the captured image at the variable frame rate. And control is performed so that the frame rate of the imaging signal Spa does not decrease.

  FIG. 3 shows the imaging apparatus having the frame rate conversion processing unit 60 as a second configuration. In FIG. 3, parts corresponding to those in FIG. For example, the frame rate conversion processing unit 60 performs frame addition by performing frame addition.

    The image signal generated by the image signal generation unit 20 is supplied to the frame rate conversion processing unit 30 and the frame rate conversion processing unit 60. Further, the control unit 50 generates a control signal CTM for setting the number of frames to be added in the frame addition process according to the frame rate of the variable-speed frame rate captured image, and supplies the control signal CTM to the frame rate conversion processing unit 60.

  The frame rate conversion processing unit 60 performs frame addition processing of the image signal DVa with the number of added frames based on the control signal CTM supplied from the control unit 50, and varies the frame rate of the image signal DVa. This frame addition process can also be performed using a RAM. For example, when performing addition of three frames, the image signal DVa of the first frame is stored in the RAM-1, and the signal stored in the RAM-1 is read out and added to the image signal DVa of the second frame to obtain the RAM-2. Remember me. The addition signal stored in the RAM-2 is read out, added to the image signal DVa of the third frame, and stored in the RAM-3. The signal stored in the RAM-3 is a signal obtained by adding the image signals DVa for three frames. If this signal is read and the signal level is multiplied by (1/3), the signal level is the required level and the frame The signal is obtained by multiplying the rate by (1/3). Further, the image signal DVa of the fourth frame is stored in the RAM-1, the signal stored in the RAM-1 is read out, added to the image signal DVa of the fifth frame, and stored in the RAM-2. The addition signal stored in the RAM-2 is read out, added to the image signal DVa of the sixth frame, and stored in the RAM-3. The signal stored in the RAM-3 is a signal obtained by adding the image signals DVa for three frames. If this signal is read and the signal level is multiplied by (1/3), the signal level is the required level and the frame The signal is obtained by multiplying the rate by (1/3). In the same manner, the image signal DVc with the frame rate (1/3 times) can be sequentially generated.

  The frame addition process can also be performed using a frame delay circuit. For example, the image signal DVa of the first frame is delayed by two frame periods by the frame delay circuit, and the image signal DVa of the second frame is delayed by one frame period by the frame delay circuit. The delayed first frame image signal and second frame image signal DVa are added to the third frame image signal DVa to obtain a signal obtained by adding the image signals DVa for three frames. By multiplying the signal level of this signal by (1/3), it is possible to obtain an image signal DVc having a required signal level and a frame rate of (1/3) times.

  By performing the frame addition process in this way, for example, the frame rate of the image signal DVa is “60P (the number indicates the number of frames per second, P indicates a progressive signal, and in other cases, Is the same)), an image signal of “30P” can be obtained by setting the number of added frames to two. Further, if the number of added frames is 4, a “15P” image signal can be obtained.

  In addition to switching the number of added frames, the frame rate of the captured image can be varied continuously by controlling the signal readout from the image sensor to vary the frame rate of the image signal Spa. It becomes. Here, when the frame rate of the imaging signal Spa is varied, the frame is obtained by controlling the charge accumulation period in the imaging element, the readout timing of the imaging charge, and the like by the drive control signal RC supplied from the driving unit 22 to the imaging unit 21. An imaging signal Spa with a variable rate can be obtained. Further, assuming that the CDR method (Common Data Rate: common sampling frequency method) is used, the length of the horizontal blanking period or the vertical blanking period is adjusted, and the imaging frame rate FRp is changed. Even if the imaging frame rate FRp is varied, it is possible to generate an imaging signal Spa in which the image size of the effective screen period does not change. Further, by using the CDR method, it is not necessary to vary the operating frequency of each part using the imaging frame rate FRp according to the imaging frame rate FRp, and the configuration is simplified.

  FIG. 4 shows the relationship between the number of added frames FA and the frame rate (imaging frame rate) FRp of the imaging signal Spa with respect to the frame rate (variable frame rate) FRc of the variable-speed frame rate captured image. For example, as shown in FIG. 4, when the variable frame rate FRc is set within the range of “60P ≧ FRc> 30P”, the number of frames FA to be added by the frame rate conversion processing unit 60 is set to “1”, and the imaging frame The rate FRp is made equal to the variable frame rate FRc. When the variable frame rate FRc is set within the range of “30P ≧ FRc> 20P”, the number of added frames FA is set to “2”, and the imaging frame rate FRp is set to twice the variable frame rate FRc. When the variable frame rate FRc is set within the range of “20P ≧ FRc> 15P”, the number of added frames FA is set to “3”, and the imaging frame rate FRp is set to three times the variable frame rate FRc. Similarly, the variable frame rate FRc can be continuously varied by switching the imaging frame rate FRp and the number of added frames FA.

  The frame rate conversion processing unit 30 converts the frame rate of the image signal DVa at the imaging frame rate into the image signal DVb at the input frame rate. Here, the frame rate of the image signal DVa is set within the range of “60P ≧ FRc> 30P” regardless of the variable frame rate FRc. For this reason, the higher the input frame rate of the image display device, the more the frame image image DVa is thinned out in the frame rate conversion process, and the image being captured can be displayed with high image quality while being updated at a high frame rate. Further, even when the image being captured is updated at a high frame rate and displayed on the image display device with high image quality, the image signal DVc having a variable frame rate is output from the frame rate conversion processing unit 60 as the main line image signal. Can do.

  Furthermore, if the frame rate of the imaging frame rate FRp is set high so that only the addition frame number is switched, the frame image of the image signal DVa in the frame rate conversion processing unit 30 increases as the input frame rate of the image display device increases. Can be repeated, and the image being captured can be displayed with high image quality.

  When only switching the number of added frames is performed, the image signal generation unit 20 drives the image sensor based on the drive control signal RC-a from the drive unit 22a, as in the third configuration of the imaging apparatus shown in FIG. Then, an imaging signal Spa-a having a constant frame rate is generated and supplied to the frame rate conversion processing unit 30 and the frame rate conversion processing unit 60. The frame rate conversion processing unit 60 performs frame addition based on the control signal CTM from the control unit 50, and outputs an image signal DVc in which the frame rate of the image signal DVa-a is “1 / FA” times. The frame rate conversion processing unit 30 performs frame rate conversion of the image signal DVa-a to generate an image signal DVb having an input frame rate.

  Here, if the imaging frame rate FRp is fixed to a frame rate equal to or higher than the input frame rate, the frame rate of the variable-speed frame rate captured image is switched stepwise, but the same frame is added to add the number of frames. It is possible to eliminate the generation of the image signal DVb by repeating the above image.

  In the above-described embodiment, the frame rate conversion processing unit 30 performs frame rate conversion by controlling writing and reading of signals to and from the RAM, and the frame rate conversion processing unit 60 performs frame addition processing and performs frame rate conversion. Although the conversion is performed, the frame rate conversion performed by the frame rate conversion processing units 30 and 60 is not limited to this process. For example, the frame rate conversion processing unit 30 may perform frame addition, or the frame rate conversion processing unit 60 may control the writing and reading of signals to and from the RAM to perform frame rate conversion. Furthermore, other frame rate conversion processing methods, for example, a method of changing the frame rate by reducing the number of frames by thinning out frames or generating an interpolated image by motion prediction to increase the number of frames can be used.

  As described above, the image pickup apparatus according to the present invention can display an image being picked up with high image quality when the image is picked up with a variable frame rate. It is suitable for.

It is a figure showing the 1st composition of an imaging device. It is a figure which shows the structure of a frame rate conversion process part. It is a figure which shows the 2nd structure of an imaging device. It is a figure which shows the relationship between the addition frame number with respect to a variable frame rate, and an imaging frame rate. It is a figure which shows the 3rd structure of an imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Imaging device, 20 ... Image signal generation part, 21 ... Imaging part, 22, 22a ... Drive part, 23 ... Imaging signal processing part, 30, 60 ... Frame rate conversion Processing unit, 31-a to 31-c ... RAM, 32 ... Write control unit, 33, 35 ... Signal selector, 34 ... Reading control unit, 40 ... Frame rate detection unit, 50 ... Control unit, 51 ... User interface unit, 100 ... External device

Claims (3)

Image signal generation means for generating an image signal of a variable-speed frame rate captured image;
Frame rate detection means for detecting the input frame rate of the connected external device;
First frame rate conversion processing means for converting an image signal of the variable-speed frame rate captured image into an input frame rate detected by the frame rate detection means;
The first frame rate conversion processing means changes the frame rate of the image signal by selecting the number of frames to be added according to the input frame rate from the external device when performing the frame addition processing of the image signal. Adding frame number selection means,
When the external device is compatible with a plurality of input frame rates, the frame rate detection means detects the maximum value of the frame rate,
The first frame rate conversion processing unit converts the image signal of the variable-speed frame rate captured image into the maximum value of the input frame rate detected by the frame rate detection unit, and converts the image signal after the frame rate conversion. Output as monitor image signal,
When the input frame rate is not detected by the frame rate detection means by the frame rate detection means, an image signal that has not been subjected to frame rate conversion by the first frame rate conversion processing means is output as a main line image signal. ,
An imaging apparatus characterized by that. A second frame rate conversion processing means for performing frame rate conversion of an image signal generated by the image signal generation means, further provided,
Outputting the image signal whose frame rate has been converted by the second frame rate conversion processing means as a main line image signal ;
The imaging device according to claim 1. The imaging apparatus according to claim 1 or 2, wherein the image signal generation unit generates an image signal of a variable-speed frame rate captured image at a frame rate equal to or higher than the input frame rate of the external device.

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