Error detection/correction and fault detection/recovery – Pulse or data error handling – Error detection for synchronization control
Reexamination Certificate
2000-05-24
2003-07-08
Ton, David (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Error detection for synchronization control
C714S755000
Reexamination Certificate
active
06591396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a moving image communication quality determination apparatus and in particular to a moving image communication quality determination apparatus for evaluating the quality of a digital image in digital moving image communications.
2. Description of the Related Art
The international standards for digital moving image code (simply, moving image code) include MPEG (Motion Picture Expert Group)-2 (ISO/IEC-13818) and MPEG-4 (ISO/IEC-14496) by ISO (International Organization for Standardization) and IEC (International Electrotechnical Commission) of international standardization organizations and H.261, H.263, etc., of ITU (International Telecommunication Union) Recommendations, for example. In the description to follow, unless otherwise specified, the moving image code refers to a moving image code conforming to the above-mentioned international standards. Alternatively, it is also applied to the moving image code based on a prediction coding technique used in the above-mentioned international standards.
For example, the main portion of “Douga tuushin souchi (moving image communication apparatus)” of Japanese Patent Application No. Hei 10-052531 by the present inventor (an example in a related art) corresponds to a moving image communication quality determination apparatus for evaluating the quality in communication using such moving image code. The corresponding portion relevant to the description of the invention will be briefly discussed for easy comparison with the configuration of the apparatus of the invention.
FIG. 4
is a block diagram to show a configuration example of an image processing system containing a moving image communication analysis apparatus according to the example in the related art. A transmitter
112
and a receiver
135
are connected to a network
20
for transferring digital moving image code (simply, moving image code) in real time. In the transmitter
112
, a moving image encoder
110
prepares moving image code and outputs the prepared moving image code to the network
20
through a moving image transmission section
111
. In the receiver
135
, a moving image reception section
131
receives input moving image code and outputs the received moving image code to a moving image decoder
130
. The moving image decoder
130
decodes the input image code and outputs the provided digital moving image to a display
133
. The display
133
displays the input digital moving image on a display screen.
The quality of the provided digital image displayed on the display
133
from the transmitter
112
is degraded because of the following causes:
First, the causes of degradation of the image quality include a transmission error of data of moving image code, packet discard in a transmission packet group, a transmission delay of data of moving image code, fluctuation of the delay, and the like.
Next, the degradation of the image quality spreads or a fault in the moving image decoder
130
occurs and a processing failure occurs in decode processing of the moving image code. Further, the processing failure in the decode processing spreads or a fault in the display
133
occurs and display processing of the digital moving image displayed on the display screen of the display
133
may become faulty.
To maintain and improve the quality of the transmitted moving image code, it is important to evaluate degradation of the quality of a digital moving image as described above. Then, the receiver
135
comprises a code data section
132
for collecting received moving image code. A moving image communication analysis apparatus
40
is connected to the network
20
and detects degradation of the moving image code transferred in the network
20
. The code data section
132
transfers with no error the collected moving image code to the moving image communication analysis apparatus
40
via the network
20
. The term “transfer with no error” mentioned here refers to a method of detecting a transmission error and executing resending, etc., for transmitting data with no transmission error as a result.
The moving image communication analysis apparatus
40
outputs the input moving image code to a collected code section
402
. The collected code section
402
stores the input moving image code therein. A decoding section
404
restores the moving image code stored in the collected code section
402
to the received digital moving image and outputs the provided digital moving image to a degradation component section
405
.
On the other hand, the transmitter
112
transfers with no error the same moving image code held in the moving image encoder
110
as the moving image code transmitted in real time to the moving image communication analysis apparatus
40
via the network
20
. The term “transfer with no error” refers to processing as described above. The same moving image code as the moving image code transmitted in real time, input to the moving image communication analysis apparatus
40
is output to an original image code section
401
. The original image code section
401
stores the input moving image code therein. A decode section
403
restores the moving image code stored in the original image code section
401
to the pre-transmitted digital moving image and outputs the provided moving image restoration value (provided moving image) to the degradation component section
405
.
The degradation component section
405
calculates a difference image having as new gradation values of the digital moving image the values resulting from subtracting the gradation values of pixels of the pre-transmitted digital moving image from those of the corresponding pixels of the received digital moving image. Further, in an example showing a degradation component, the sum of the squares of all pixels of the difference image is calculated, the sum of the squares of all pixels of the pre-transmitted digital moving image is calculated, and the ratio between the square sums is found and is output as a kind of parameter representing the image quality, namely, SNR (signal to noise ratio).
Next, remedies to deal with an anomaly of moving image code and an anomaly of a display in related arts to be compared with the invention will be discussed. If the moving image code input to the moving image decoder contains an anomaly, an anomaly occurs in the provided moving image, as described above. A large number of arts of using means for detecting an anomaly of moving image code for transmission and processing of the moving image code are well known.
“Dougazou fugouka/fukugouka souchi” (moving image coding/decoding apparatus) of JP-A-8-251596 by KIKUCHI Yoshihiro (kabushikikaisha Toshiba) et al. shows a processing example of detecting an anomaly from the decode value of a moving image and the range that the decode value can take. “Dougazou data no densou houhou oyobi densou souchi” (moving image data transmission method and transmission apparatus) of JP-A-7-322248 by SHINODA Mayumi (Matushita denki sangyou kabushikikaisha) et al. shows an example of detecting an anomaly of moving image code and again making a transmission request for resending the moving image code, thereby decreasing anomalies of the transmitted moving image code.
Next, anomalies occurring in moving image code transmitted via a network will be discussed in detail. First, as one of the anomalies occurring in moving image code, when an agreement of conforming to each standard as described above is made, the moving image code may contain code out of standard because of a transmission error of the moving image code, a failure of a moving image encoder, etc. If the code portion out of standard is input to a moving image decoder, the moving image decoder stops decoding the code out of standard and performs the preparation operation for detecting another normal code, then restarts decoding the normal code in the moving image code.
The decode operation of the moving image decoder will be discussed in detail with reference to
FIGS. 5A and 5B
, which are conceptual drawing
Ando Electric Co. Ltd.
Fish & Richardson P.C.
Ton David
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