JP4373689B2 - Television camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a television camera using a charge coupled device as an image sensor, and more particularly to a television camera using a high resolution image sensor having a large number of pixels.
[0002]
[Prior art]
In recent years, most television cameras have been occupied by CCDs (charge coupled devices) as image sensors (imaging devices). However, these CCD image sensors have also recently achieved high pixel density. Of course, hundreds of thousands of orders are, of course, and millions of pixels are not uncommon.
[0003]
By the way, this CCD image pickup device (hereinafter simply referred to as an image pickup device) has a characteristic that an upper limit is given to the frame rate depending on the number of pixels. Therefore, when a high-resolution image pickup device is used, a frame is accordingly generated. For example, the frame rate of 30 fps (frame / second) in the NTSC system cannot be supported.
[0004]
Therefore, as a technique for suppressing such a decrease in the frame rate, a so-called draft reading method has been conventionally known in which when a signal is read from the image sensor, reading of the signal from the pixel is thinned out. A conventional television camera to which such a draft reading system is applied will be described with reference to FIG.
[0005]
Note that the television camera shown here is an example of a case where it can be used by arbitrarily switching between the all-pixel readout method and the draft readout method. A normal reading method in which signals are read from all pixels of the element will be referred to as an all-pixel reading method.
[0006]
In FIG. 7, first, the draft read pulse generation circuit 1 and the draft read drive pulse 1a and the draft read necessary for reading the image signal from the image pickup device 4 by the draft read method in order to increase the frame rate. It functions to generate the sync pulse 1b.
[0007]
Next, the all-pixel readout pulse generation circuit 2 is used for all-pixel readout necessary for reading out the image signal from the image sensor 4 by the all-pixel readout method so as to obtain a high-resolution image signal. It serves to generate the drive pulse 2a and the all-pixel readout synchronization pulse 2b.
[0008]
Further, as shown in the figure, the operation mode selector 3 includes two switches S1 and S2 that are operated in conjunction with each other for switching between the above-described two methods. The switch S1 includes a draft reading drive pulse 1a and a switch S1. The all-pixel readout drive pulse 2a is switched and the selected pulse is output as the drive pulse 3a. The switch S2 switches between the draft readout synchronization pulse 1b and the all-pixel readout synchronization pulse 2b and selects the selected one. The pulse is output as the drive pulse 3a.
[0009]
Therefore, the image pickup device 4 is driven by the drive pulse 3a and outputs a subject image signal 4a, and the video processing circuit 5 performs video processing so that the image signal 4a can be connected to an external device at the timing of the synchronization pulse 3b. The video signal 5a is output.
[0010]
Next, the operation of the television camera shown in FIG. 7 will be described. First, assuming that the camera operator operates the operation mode selector 3 and switches the switches S1 and S2 so as to be in the state shown in FIG. The reading of the image signal from the element 4 is based on the draft reading method. As a result, the image signal 4a at this time is as shown in FIG.
[0011]
Here, FIG. 8 is an explanatory diagram of a pixel in which a signal is read out in a frame period among the pixels of the image pickup device 4, and a frame image that is continuous in a certain period of image signals composed of continuous frames. 001, 002, 003, and 004 are extracted and shown.
[0012]
In each of the frame images 001 to 004 in FIG. 8, the pixels colored in light black represent the pixels from which signal readout is thinned out. Therefore, in this case, the pixels in the horizontal direction remain as they are. Sequentially, two pixels are thinned out in the vertical direction, and 2/3 pixels are thinned out, and the image signal is read out only from the remaining 1/3 pixels. I understand.
[0013]
Next, assuming that the camera operator operates the operation mode selector 3 and switches the switches S1 and S2 to the opposite state to that shown in the figure, the image signal is read from the image sensor 4 to the all-pixel reading method. As a result, it can be seen that the image signal 4a at this time is in a state where the image signal is read from all the pixels as shown in FIG.
[0014]
In this case, in the case of the draft reading method of FIG. 8, since the image signal is read from only 1/3 of the pixels, the reading time of 1/3 in the case of the all-pixel reading method of FIG. However, in this case, it is unavoidable that the resolution becomes 1/3 of that in the case of the all-pixel readout method of FIG.
[0015]
For example, in the case of the all-pixel readout method of FIG. 9, if it takes 1/20 second to read out one frame, the frame rate at this time is 20 fps, but in the case of the draft readout method of FIG. 1 frame can be read in 1/60 second, and as a result, the frame rate is tripled to 60 fps.
[0016]
Therefore, according to the television camera described with reference to FIG. 7, when the frame rate is a problem, the operation mode may be selected as the draft reading method. On the other hand, when high resolution is required, It can be operated by a pixel readout method and can easily cope with any case.
[0017]
Here, it goes without saying that the resolution when operating in the all-pixel readout method is given depending on the number of pixels of the image sensor 4.
[0018]
[Problems to be solved by the invention]
The above prior art has only to select one of a draft reading method capable of maintaining a high frame rate and an all-pixel reading method capable of obtaining a high resolution. Therefore, there is a problem in maintaining both the frame rate and the high resolution. was there.
[0019]
An object of the present invention is to provide a television camera that can maintain a high frame rate while fully utilizing the resolution characteristics of an image sensor.
[0020]
[Means for Solving the Problems]
In the television camera using a charge coupled device as an image pickup device, the object is to generate a pulse generation unit that operates the image pickup device alternately by an all-pixel reading method and a draft reading method, and an image signal read from the image pickup device. Interpolation calculation means is provided as an input, and the interpolation calculation means performs interpolation calculation on the portion read by the draft reading method in the image signal, and reads by the all-pixel reading method in the image signal. This is achieved by converting the frame rate of the portion and the portion read by the draft reading method to a constant frame rate .
[0021]
At this time, recording means for recording the image signal read from the imaging means may be provided .
[0022]
Similarly, at this time, recording means for recording the video signal output from the interpolation calculation means may be provided.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a television camera according to the present invention will be described in detail with reference to embodiments shown in the drawings.
[0024]
First, FIG. 1 is a block diagram of a television camera according to an embodiment of the present invention. In this figure, reference numeral 10 denotes an alternating drive read pulse generation circuit, and in addition, an image sensor 4 and a video processing circuit 5 are shown in FIG. This is the same as the conventional television camera described in FIG.
[0025]
Therefore, in this embodiment, in the block configuration, the alternate drive readout pulse generation circuit 10 is used instead of the draft readout pulse generation circuit 1, the all-pixel readout pulse generation circuit 2, and the operation mode selector 3 in the television camera of FIG. Is equivalent to that provided.
[0026]
The alternate drive read pulse generation circuit 10 functions to generate an all pixel / draft alternate drive pulse 10a and an all pixel / draft alternate synchronization pulse 10b, respectively, and supply them to the image sensor 4 and the video processing circuit 5, respectively. .
[0027]
Here, first, the all-pixel / draft alternate drive pulse 10a has a pulse pattern necessary for operating the image pickup device 4 by alternately switching between the all-pixel readout method and the draft readout method every frame period. This means that the all-pixel / draft alternate drive pulse 10a can be expressed as 10a = (1a + 2a), for example, as shown. 10b = 3 × 1a + 2a, 10a = 2 × 1a + 2a may be used.
[0028]
Next, the all-pixel / draft alternate synchronous pulse 10b is a pulse necessary for signal processing of the image signal 4a read from the image pickup device 4 by alternately switching between the all-pixel reading method and the draft reading method every frame period. This is a sync pulse having a pattern. Therefore, this can also be expressed as 10b = (1b + 2b) as shown. As described above, 10b = 3 × 1b + 2b, 10b = 2 × 1b + 2b, or the like may be used.
[0029]
Therefore, the image pickup device 4 is driven by the all-pixel / draft alternate drive pulse 10a, and the all-pixel reading operation capable of obtaining a high-resolution image and the draft reading capable of increasing the frame rate by thinning out the pixel reading. The operation is repeated alternately and the image signal 4a is supplied to the video processing circuit 5.
[0030]
Then, the video processing circuit 5 inputs the image signal 4a in which the all-pixel reading operation and the draft reading are alternately repeated, and can connect this to an external device at the timing of the all-pixel / draft alternate synchronization pulse 10b. In this way, the video processing is performed and the video signal 5a is output.
[0031]
Next, the operation of the television camera of FIG. 1 will be described. Now, assuming that the alternate drive read pulse generation circuit 10 operates and all pixel / draft alternate drive pulses 10a and all pixel / draft alternate synchronization pulses 10b are alternately supplied, the image signal 4a at this time is shown in FIG. It becomes like this.
[0032]
Here, FIG. 2 is an explanatory diagram of a pixel from which signals are read out during a frame period among the pixels of the image sensor 4, and a frame image continuous in a certain period of image signals composed of continuous frames. 001, 002, 003, and 004 are extracted and shown.
[0033]
As apparent from FIG. 2, the frame image 001 and the frame image 003 are obtained by the all-pixel reading operation, and the frame image 002 and the frame image 004 are obtained by the draft reading method. In the case of, it turns out that these are alternated.
[0034]
In the frame images 002 and 004 according to the draft readout method of FIG. 2, the pixels colored in light black represent the pixels from which signal readout is thinned out, as in FIG. However, two pixels are thinned out in order in the vertical direction as they are in the horizontal direction, and 2/3 pixels are thinned out, and image signals are read out only from the remaining 1/3 pixels. It is in a state.
[0035]
Then, in FIG. 2, since the frame image 001 and the frame image 003 are based on the all-pixel readout method, signals are output from all the pixels. However, at this time, the image sensor is the same as in the conventional technique of FIG. Then, it takes 1/20 second to read out one frame image. In this case, the frame rate is 20 fps.
[0036]
On the other hand, since the frame image 002 and the frame image 004 are based on the draft reading method, the signal is read from only one pixel out of three pixels, but the reading of one frame image is finished in 1/60 second, and therefore the frame rate Becomes as high as 60 fps.
[0037]
Since these are repeated alternately, it takes 1/25 seconds + 1/60 seconds and 1/15 seconds in the 2 frame period, and 1 second results in an image of 30 frames. The average frame rate of the video signal 5a output from the circuit 5 is 30 fps. Therefore, according to this embodiment, it is possible to sufficiently cope with the frame rate of 30 fps in the NTSC system.
[0038]
Next, FIG. 3 shows a second embodiment of the television camera according to the present invention. In this embodiment, the image sensor 4 and the video processing circuit 5 and the alternate drive readout pulse generation circuit 10 in the embodiment of FIG. The video signal 5a output from the video processing circuit 5 is taken out from the television camera 11 as it is.
[0039]
In addition to the television camera 11, a recording device 12, a display device 13, and an interpolation operation circuit 20 are provided. The video signal 5 a taken out from the television camera 11 is sent to the recording device 12 and the interpolation operation circuit 20. The video signal 20 a output from the interpolation operation circuit 20 is supplied to the display device 13.
[0040]
Here, first, the recording device 12 is composed of an image signal recording device such as a VTR (video tape recorder) or a VDR (video disc recorder), and records the video signal 5a taken out from the television camera 11 as it is. To work. At this time, the recorded video signal 5a is also played back as necessary.
[0041]
Next, the display device 13 is composed of an image monitor device such as a liquid crystal display device or a plasma display device, for example, and the video signal 5 a taken out from the television camera 11 or the video signal 5 a reproduced from the recording device 12. The video signal 20a, which has been subjected to interpolation and has a constant frame rate, is input from the interpolation calculation circuit 20, and functions to reproduce an image on the display surface.
[0042]
Then, the interpolation calculation circuit 20 receives the video signal 5a, interpolates a signal portion corresponding to a pixel that is not read out at the time of draft reading based on information of neighboring pixels and all the pixel reading images before and after all pixels, After conversion to the same number of pixels as that at the time of reading, the frame rate is made constant, and the video signal 20a having the constant frame rate is output by interpolation.
[0043]
FIG. 4 shows a third embodiment of the television camera according to the present invention, in which the image pickup device 4, the video processing circuit 5, and the alternate drive readout pulse generation circuit 10 are combined into a television camera 110 as shown in FIG. Although the same as the embodiment, in the embodiment of FIG. 4, the television camera 110 further includes an interpolation operation circuit 20, and the television camera 110 performs interpolation to make the frame rate constant. The signal 20a is immediately output to the outside.
[0044]
Therefore, in the embodiment of FIG. 4, the recording device 12 ′ records the video signal 20 a having a constant frame rate, and the display device 13 records the video signal 20 a output from the television camera 110 or the recording device 12. The video signal 20a reproduced from the above is supplied as it is and displayed as a video signal with a high frame rate and high resolution.
[0045]
Next, the operation of the interpolation operation circuit 20 in the embodiments of FIGS. 3 and 4 will be described in more detail. In this case, as shown in FIG. 5, first, interpolation is performed by pixels in the vicinity within the same frame. Frame image 002 ′ using a method of performing interpolation or replacing pixels of the same coordinates corresponding to the frame image 002 at the time of draft reading from the frame images 001 and 003 at the time of reading all pixels before and after the frame. Is generated.
[0046]
At this time, in any method, a frame memory capable of storing at least three frames of the video signal 5a is used to perform calculations necessary for interpolation. Then, the interpolated video signal is stored in another frame memory, and is read out with a constant frame synchronization pulse of, for example, 30 fps, so that the video signal 20a with the frame rate fixed by interpolation can be output.
[0047]
Here, FIG. 6 shows an example of the operation of the interpolation calculation circuit 20 for the image A of the moving object. From the image A in the frame image 001 and the frame image 003 at the time of reading all pixels, the draft between these frames is shown. Since the position of the object image A in the frame image 002 at the time of reading can be predicted, an interpolated frame image 002 ′ can be generated from this.
[0048]
Then, the video signal 20a output from the interpolation calculation circuit 20 is interpolated with respect to the image by the draft reading, although the images by the all-pixel reading and the draft reading are alternately switched in units of frames. Therefore, the frame rate is increased to 30 fp, for example, while having high definition and high resolution comparable to an image obtained by reading all pixels.
[0049]
Therefore, according to the embodiments of FIGS. 3 and 4, the video signal 20 a having a high resolution and a high frame rate can be obtained, and a high-resolution image can be displayed on the display device 13.
[0050]
By the way, in the case of the above-described embodiment of FIG. 1, the video signal 5a output from the video processing circuit 5 naturally has the frame rate alternately changed to 20 fps and 60 fps, so it is somewhat convenient. I can say no.
[0051]
However, according to the embodiments of FIGS. 3 and 4, since the video signal 20a having a constant frame rate can be obtained, it can be displayed as it is on the display device 13 and the resolution of the image pickup device 4 at this time. Can be fully utilized.
[0052]
In the embodiment of FIG. 3, the video signal 5a is output from the television camera 11 as it is, but in this case, the video signal 5a has different frame periods at the time of all pixel reading and at the time of draft reading. At the time of draft reading, the signal of the thinned pixels is not transmitted, so that the transmission band necessary for the video signal 5a can be reduced correspondingly, and the recording device 12 does not record pixels that are not read at the time of draft reading. Therefore, the amount of data to be recorded can be reduced.
[0053]
On the other hand, in the embodiment of FIG. 4, since the interpolation arithmetic circuit 20 is built in the television camera 110 and the video signal 20a having a high frame rate is immediately obtained from the television camera 110, high versatility can be easily provided. it can.
[0054]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the television camera which can maintain a high frame rate, fully utilizing the resolution characteristic of an image pick-up element can be provided easily.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a television camera according to the present invention.
FIG. 2 is an explanatory diagram of a pixel from which a signal is read during a frame period of an all-pixel reading operation and a draft reading operation according to an embodiment of the present invention.
FIG. 3 is a block diagram showing another embodiment of the television camera according to the present invention.
FIG. 4 is a block diagram showing still another embodiment of the television camera according to the present invention.
FIG. 5 is an explanatory diagram showing an example of an interpolation calculation operation in the embodiment of the present invention.
FIG. 6 is an explanatory diagram showing an example of an interpolation calculation operation in the embodiment of the present invention.
FIG. 7 is a block diagram showing an example of a conventional television camera.
FIG. 8 is an explanatory diagram of pixels from which signals are read during a frame period of a draft reading operation in a television camera.
FIG. 9 is an explanatory diagram of pixels from which signals are read out during a frame period of an all-pixel reading operation in a television camera.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Draft readout pulse generation circuit 2 All pixel readout pulse generation circuit 3 Operation mode selector 4 Image sensor (CCD image sensor)
5 Video processing circuit 10 Alternating drive read pulse generation circuit 11, 110 Television camera,
Reference Signs List 12 Recording Device 13 Display Device 20 Interpolation Operation Circuit 1a Draft Read Drive Pulse 1b Draft Read Sync Pulse 2a All Pixel Read Drive Pulse 2b All Pixel Read Sync Pulse 3a Drive Pulse 3b Sync Pulse 4a Image Signal 5a Video Signal 10a Alternate Drive pulse 10b for driving and reading Synchronous pulse 20a for alternately driving and reading Video signal 001, 003 Frame image 002, 004 at the time of reading all pixels Frame image 002 'at the time of draft reading Interpolated frame image

Claims (3)

In a television camera using a charge coupled device as an image sensor,
Pulse generating means for alternately operating the image sensor in an all-pixel readout system and a draft readout system;
Interpolation calculation means for inputting an image signal read from the imaging means is provided,
Interpolation calculation is performed on the portion read by the draft reading method in the image signal by the interpolation calculation means,
Processing is performed so that the frame rate of the portion read by the all-pixel reading method and the portion read by the draft reading method in the image signal is converted to a constant frame rate. A TV camera featuring In the invention of claim 1 ,
A television camera comprising recording means for recording an image signal read from the imaging means. In the invention of claim 1 ,
A television camera comprising recording means for recording a video signal output from the interpolation calculation means.

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