Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1998-02-19
2002-07-02
Chin, Wellington (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S535000, C370S536000
Reexamination Certificate
active
06414972
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a signal decoding method, a signal decoding apparatus, a signal multiplexing method, a signal multiplexing apparatus, and a recording medium and, more particularly to an apparatus and a method of implementing decoding and multiplexing in which amount of signals to be decoded can be reduced with effects on a regenerated image effectively suppressed, and an apparatus and a method in which multiplexed signals are decoded properly.
The present invention also relates to a recording medium which stores the multiplexed signals and a recording medium which stores a program for implementing the decoding and the multiplexing in a computer.
BACKGROUND OF THE INVENTION
In order to record and transmit large volumes of image data with efficiency, techniques for compressing the image data are extremely important. So far, as the techniques, information compressive techniques according to standards such as JPEG (Joint Photographic Coding Experts Group), MPEG(Moving Picture Experts Group), and so forth have been developed. Image data of an image or a moving picture series is handled in MPEG and JPEG.
There is an image termed “a composite image”. The “composite image” comprises plural small images (object images).
FIG. 8
is a diagram showing a concept of this composite image.
Referring now to
FIG. 8
, a final composite image
707
comprises a background image
701
, and images
702
to
705
of objects A and B located in front of the background image
701
. Note that a background image of a composite image is also an image of an object.
Specifically, the background image
701
and the image
702
of the object A are composited to generate a composite image
706
. At this time, a transparency signal indicating a composition ratio of a pixel value of the background image
701
to a pixel value of the image
702
, is used. The image
703
is an image represented by the transparency signal of the object A, which indicates transparency of the image of the object A.
Further, the composite image
706
and the image
704
are composited on the basis of a transparency signal of the object B as mentioned above, to generate the composite image
707
. An image
705
is an image of the object B represented by the transparency signal of the object B, which indicates transparency of the image of the object B.
In a case where a moving picture is a composite image, a background image and an image of each object thereof are respectively assumed to be a moving picture series. Therefore, images of frames of each moving picture series are composited, to generate a composite moving picture comprising plural moving picture series.
FIG. 9
is a block diagram showing a prior art image multiplexing apparatus which codes and multiplexes image signals of a composite image and an image decoding apparatus which decodes multiplexed coded signals of the composite image.
Referring now to
FIG. 9
, an image multiplexing apparatus
801
is used for coding and multiplexing image signals (digital image data) of respective objects of the composite image, and an image decoding apparatus
802
is used for receiving and decoding multiplexed signals MEg output from the image multiplexing apparatus
801
.
More specifically, the image multiplexing apparatus
801
comprises plural coding means
40
a
1
to
40
an
for coding image signals Sg
1
to Sgn of plural objects of the composite image, to produce coded signals Eg
1
to Egn, respectively, and multiplexing means
412
for multiplexing the coded signals Eg
1
to Egn to produce multiplexed coded signals MEg.
In the image multiplexing apparatus
801
so constructed, when the image signals Sg
1
to Sgn are input, the coding means
40
a
1
to
40
an
code the image signals Sg
1
to Sgn, respectively, and outputs the coded signals Eg
1
to Egn to the multiplexing means
412
, which multiplexes the coded signals Eg
1
to Egn and outputs the multiplexed signals MEg to a transmission path
803
.
Meanwhile, the image decoding apparatus
802
comprises demultiplexing means
102
for demultiplexing the multiplexed signals MEg to separate the coded signals Eg
1
to Egn from the multiplexed signals MEg, a decoding unit
101
for sequentially decoding the coded signals Eg
1
to Egn in accordance with a control signal C
1
, synthesizing means
110
for receiving decoded signals Dg of respective objects output from the decoding unit
101
and synthesizing the decoded signals Dg in accordance with a control signals C
2
to produce synthesized reproduced signals Rs, and a CPU
108
for producing the control signals C
1
and C
2
.
The decoding unit
101
comprises a select switch
103
for selecting the separated coded signals Eg
1
to Egn in the order in accordance with the control signal C
1
, and decoding means
109
for decoding a selected output Se of the select switch
103
to produce the decoded signal Dg. The CPU
108
has a capability of controlling switching of the select switch
103
by the control signal C
1
, and instructing the synthesizing means
110
on a synthesizing method by the control signal C
2
.
In the image decoding apparatus
802
so constructed, when the multiplexed signals MEg output from the image multiplexing apparatus
801
are input through the transmission path
803
, the multiplexed signals MEg are demultiplexed by the demultiplexing means
102
to produce the coded signals Eg
1
to Egn.
At this time, the CPU
108
produces the control signals C
1
and C
2
. The select switch
103
selects one of the coded signals Eg
1
to Egn in accordance with the control signal C
1
and outputs the selected signal Se to the decoding means
109
, which decodes the selected signal Se and outputs the decoded signal Dg to the synthesizing means
110
, which synthesizes the decoded signals Dg in accordance with the control signal C
2
and, outputs the synthesized reproduced signals Rs.
A case of processing the composite moving picture comprising plural small images using these apparatus will be described. When image signals of moving picture series of respective objects are input to the image multiplexing apparatus
801
, the coding means
40
a
1
to
40
an
code the image signals, respectively, and the multiplexing means
412
multiplexes these coded signals and outputs the multiplexed signals MEg to the image decoding apparatus
802
. In the image decoding apparatus
802
, the demultiplexing means
102
separates the coded signals Eg
1
to Egn of respective objects of the moving picture series from the multiplexed signals MEg, the decoding unit
101
decodes these coded signals, and the synthesizing means
110
synthesizes the decoded signals Dg and outputs the synthesized reproduced signals Rs of the composite moving picture comprising the moving picture.
Note that in the image multiplexing apparatus
801
, information required for compositing images, such as compositing order, size, and compositing positions of images of respective objects is also multiplexed and transmitted during multiplexing the coded signals.
However, since the composite image comprises plural images, load on decoding is increased as compared with a case where an image is decoded. For this reason, in decoding in software using a general purpose computer, the size and number of images to be decoded within a given time are limited depending on capability of the CPU. In addition, in a case where the composite image comprises a moving picture, although coded signals of a prescribed amount must be decoded within a given time, if the decoding is not completed within the given time, display delay or overflow of an input buffer occurs.
As should be appreciated from the forgoing, it is important that decoding be controlled depending on capability of a decoding apparatus when the coded signals of the composite image are decoded. However, in the prior art, it is difficult to control the decoding, since insufficient capability of the decoding apparatus is not taken into account.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and an
Hagai Makoto
Hatakeyama Takeshi
Chin Wellington
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel LLP
Pham Brenda H.
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