Television – Camera – system and detail – Still and motion modes of operation
Reexamination Certificate
1996-10-24
2003-08-26
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Still and motion modes of operation
C348S446000
Reexamination Certificate
active
06611286
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image sensing apparatus and, more particularly, to an image sensing apparatus, using a non-interlace scanning type image sensing device, capable of encoding image data obtained by the image sensing device in accordance with movement of an object sensed, and outputting a smooth moving image when reproducing image data recorded on a recording medium.
Recently, a non-interlace scanning type image sensing device capable of sequentially reading signals of all the pixels has been developed with the progress of semiconductor manufacturing technique.
The non-interlace scanning type image sensing device has an advantage in that a higher resolution image can be obtained with less blurring than an image sensed by using a conventional interlace scanning type image sensing device even when sensing a moving object.
In the interlace scanning type image sensing device, a frame image is composed of two field images which are sensed at different times, usually at a field period interval. Accordingly, there is a problem in which, when sensing a fast moving object, there are notches on edges of the object and perhaps of the background in a frame image because of the time gap between the two field images composing a frame image.
If a frame image is made of image data of a single field image to overcome the aforesaid problem, there would not be notches on edges, however, since the amount of image information in the vertical direction is halved compared to a frame image composing of two field images, the vertical resolution of the obtained frame image is also halved.
In contrast, with a non-interlace scanning type image sensing device, it is possible to sense a frame image in the same time period as that for sensing a field image by an interlace scanning type image sensing device, thus, the above problem does not arise. By taking this advantage of the non-interlace scanning type image sensing device, it is applied to a still image camera and an input device for use with a computer, for example.
Further, in a still image output device, such as a video printer, which has rapidly spread in the market in these days, a user can arbitrary pick up a desired scene out of images which are sensed as a moving image. Accordingly, there is a demand to use the non-interlace scanning type image sensing device as an image sensing unit of a video camera capable of sensing both a moving image and a still image.
When a non-interlace scanning type image sensing device is used as an image sensing unit of a video camera capable of sensing both a moving image and a still image, as described above, a couple of methods for generating moving image signals can be considered.
A case where a non-interlace scanning type image sensing device is used in a digital video camera of NTSC standard, as shown in
FIG. 7
, will be explained as an example. A non-interlace scanning type image sensing device
1
has a structure to output signals by two channels, and each channel always outputs either image signals of even lines or image signals of odd lines of the non-interlace type image sensing device
1
.
Further, in
FIG. 7
, image signals of the even lines and odd lines are alternatively outputted from each channel of the non-interlace scanning type image sensing device
1
in each field period in accordance with timing signals generated by a timing signal generator (TG)
15
. For example, referring to one of the two output channels, when image signals of even lines are outputted from one of the channel in a given field period, image signals of odd lines are outputted in the next field period, then image signals of even lines are outputted in the following field period. Image signals read out from the non-interlace scanning type image sensing device
1
are respectively inputted to correlated double sampling (CDS) circuits
201
and
202
. The signals outputted from the CDS circuits
201
and
202
are inputted to automatic gain controllers (AGCs)
301
and
302
, thereafter enter analog-digital (A/D) converters
401
and
402
, respectively.
Then, after the analog signals are converted into digital signals by the A/D converters
401
and
402
, enter a camera signal processing circuit
5
. The camera signal processing circuit
5
performs signal processes, such as color separation, edge enhancement, and color correction, after the image data of the even lines and odd lines are applied with dot sequential processing.
After the aforesaid processes are completed, the camera signal processing circuit
5
divides a frame image, and image data of one field (e.g., image data of even lines) is outputted from the first channel ch
1
, and image data of the other field (e.g., image data of odd lines) is outputted from the second channel ch
2
. Similarly, for the next frame image, image data of alternate fields are outputted from the first and second channels ch
1
and ch
2
. For example, image data of odd lines is outputted from the first channel ch
1
, and image data of even lines is outputted from the second channel ch
2
.
The non-interlace scanning type image sensing device
1
can generate a frame image in one field period, however, a recording device (e.g., a digital VTR) can record only a field image in one field period.
Accordingly, as shown in
FIG. 8A
, by using either the image signals outputted from the first channel ch
1
or the image signals outputted from the second channel ch
2
, an image of a single field is outputted in each field period (a mode for performing the aforesaid operation is called “field image sensing mode”, hereinafter).
Referring to
FIG. 8A
, the camera signal processing circuit
5
sequentially writes field image data of a first frame image #
1
and of a second frame image #
2
outputted from the first channel ch
1
to a first frame memory
601
in the first and second field periods in accordance with a control signal C
1
.
Meanwhile, if image data is written in a second frame memory
602
, the image data of one previous frame period is sent to an encoding processing circuit
7
in accordance with a control signal C
2
. In the encoding processing circuit
7
, the image data is applied with processes, such as discrete cosine transform (DCT) and shuffling, thereafter, stored in a magnetic tape
9
by a recording head
8
as digital image signals in a recording method complying with a format.
After image data of one frame is written in the first frame memory
601
, the camera signal processing circuit
5
sequentially writes field image data of the third frame image #
3
and of the fourth frame image #
4
outputted from the first channel ch
1
to the second frame memory
602
in the third and fourth field periods in accordance with the control signal C
2
.
Meanwhile, the image data of one previous frame period is sent to the encoding processing circuit
7
in accordance with a control signal C
2
. In the encoding processing circuit
7
, the image data is applied with the same processes as described above, thereafter, stored in the magnetic tape
9
by the recording head
8
as digital image signals in the recording method complying with the format.
The image signals which are recorded as above is processed as shown in
FIG. 8B
when they are reproduced. First, the image signals read from the magnetic tape
9
by the read head
10
are sent to a decoding processing circuit
11
in the first and second field periods, and applied with signal processes, such as inverse discrete cosine transform (I-DCT) and de-shuffling. Thereafter, the image signals are written to a third frame memory
121
in accordance with a control signal C
3
.
Meanwhile, if image data is written in a fourth frame memory
122
, the decoding processing circuit
11
reads image data from the fourth memory
122
in accordance with a control signal C
4
, and reproduces an image by an even line field and an odd line field separately.
In the third and fourth field periods, the image signals read from the magnetic tape
9
by the read head
10
are transmitted to the decoding
Suzuki Toshihiko
Terasawa Ken
Garber Wendy R.
Nguyen Luong
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