Optics: motion pictures – With film carried control signals
Reexamination Certificate
2003-02-13
2004-08-17
Adams, Russell (Department: 2851)
Optics: motion pictures
With film carried control signals
C714S746000
Reexamination Certificate
active
06778254
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technical Field to which the Invention Belongs
The present invention relates to a motion picture code evaluator and in particular to a motion picture code communications evaluation technology to evaluate the code and the protocol used in transmission/reception of digital motion picture data.
2. Prior Art
A digital motion picture is a continuous sequence of instantaneous pictures in time called motion picture frames (hereinafter referred to as frames).
Data of a digital motion picture is generally huge. Thus, motion picture code transmission is generally performed where compression or encoding of information is made for data communications, followed by a decoding process to regenerate a motion picture.
Standards for motion picture codes includes, for example, MPEG (Moving Picture Experts Group)-2 (ISO/IEC13818) and MPEG-4 (ISO/IEC14496) specified by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission), and H.261 and H.263 specified by ITU (International Telecommunication Union) recommendations.
The present invention is applicable to similar motion picture codes as well as the international standards.
In the aforementioned motion picture code, frames comprise pixels arranged in a shape of a grating. A frame has a format such as the CIF format comprising 352 pixels in the horizontal direction and 288 pixels in the vertical direction and the QCIF format 176 pixels in the horizontal direction and 144 pixels in the vertical direction.
The number of pixels which constitute a frame is also called a screen size.
In the case of a color image, the number of pixels available in the CIF format are a luminance screen (Y) and a color difference screen (U, V). A 4:2:0 format which assigns one pixel to U information on the color difference screen and one pixel to V information on the color difference screen per two by two pixels on the luminance screen, and a 4:2:2 format which assigns one pixel to U information on the color difference screen and one pixel to V information on the color difference screen per two pixels on the luminance screen are available.
The number of pixels on the color difference screen in the 4:2:2 format is double that in the 4:2:0 format.
The primary colors, RGB (red, green, blue), may be used to represent respective number of pixels.
The number of pixels indicates luminance and color difference or all pixels of the primary colors.
It goes without saying that the more the number of pixels per frame is, the higher-resolution or higher-quality picture is obtained.
The number of frames per unit time may be 30 frames per second or 15 frames per second. The greater this figure is, the smoother motion is represented, that is, the higher-quality picture is obtained.
In digital representation of luminance, intermediate halftones from the darkest black to the lightest white are quantized.
In such a case, the quantization level represented by a digital value is finite. In general applications, levels in the neighborhood of 256-level gray scale which can be visually represented in eight bits are used.
The number of colors is infinite when colors are digitally represented. Colors around 16 million colors are used.
Such colors may be the number if levels of gray scale quantization.
The number of quantization levels is the number of colors unless otherwise specified.
In this case also, the more the number of gray-scale levels is, the higher-quality picture is obtained.
The total number of quantization levels gathered for the pixels in all the frames within a specific time is called motion picture information amount.
In general, the number of pixels of a frame and the number of frames per second are constant, although there are cases where the number of pixels or frames varies.
The number of quantization levels may vary within a frame.
In terms of a load on a transmission path, transmitter or receiver, the smaller the amount of motion picture codes is, the smaller the load is.
Thus, a higher amount of motion picture codes for the information amount of a picture before compression of information, that is, a higher compression rate or coding is desirable.
In a motion picture code according to the international standards or equivalent, the actual coding efficiency is limited. To reduce a load on a transmission path, transmitter or receiver, it is practically efficient to reduce the number of pixels, frames, and quantization levels. This degrades the picture quality.
Actual operation in transmission of motion pictures is costly. Thus, a service method is available which charges by the amount of information in motion pictures, in order to compensate for a load on a transmission path, transmitter or receiver.
Quality degradation of a motion picture in the course of transmission of a motion picture code will be described.
In communications of a motion picture code, the receiving party obtains a lower quality picture than the original for the following reasons:
A transmission error may prevent a motion picture code from being properly received.
Some packets may be lost halfway as a result of data transmission in packets.
Communications of motion picture codes may take excessive time. An encoded motion picture frame may not be ready for display at the timing of the display in the ongoing motion picture playback. In this case, display of the motion picture frame is skipped to shift to the processing of the next motion picture frame.
In this way, a section which failed to display an encoded picture of the original motion picture is called a loss of motion picture.
A transmission error has different affects on the decoded motion picture to be displayed, depending on the section where the error has taken place.
A section which accommodates parameters to represent the specifications for the entire motion picture codes such as the screen size of a motion picture code and a color difference format as well as codes used in the predictive coding system and prediction method for the entire frame is called a header.
In case a transmission error has occurred in the header section, display of the entire decoded motion picture may be disabled or display of the entire decoded frame may be disabled.
In case a transmission error has occurred in a section concerning the gray-scale level of pixels in a frame, display of the decoded pixel may be disabled.
In this way, the amount of motion picture codes not used for display of decoded pictures due to a transmission error and a delay and the amount of loss of a decoded motion picture are not in a fixed relationship. Thus, a loss of the motion picture must be evaluated on demand.
The example of reference by the same inventor, US-2002-0097803-A1 “Method for evaluating dynamic image code communications, and apparatus for evaluating the same” provides apparatus to evaluate the motion picture information amount and motion picture loss amount.
A configuration example thereof will be described using FIG.
2
.
A motion picture code transmitter
11
transmits a motion picture code, which is received and recoded by a motion picture code receiver
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.
The amount of motion picture codes is counted on a motion picture code counter
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.
A motion picture loss evaluator
33
evaluates a motion picture loss amount as described below.
A motion picture quality evaluation value converter
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subtracts the motion picture loss amount from the motion picture information amount.
The principle configuration and operation of the aforementioned motion picture loss evaluator
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, which is described in the Japanese Patent Application No. 153078/1999 “Motion picture communications quality determination apparatus” will be outlined below.
The motion picture loss evaluator
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decodes the motion picture codes then records accurately decoded areas and estimates non-recorded areas as losses.
Problems that the Invention is to Solve
In case a service is provided where transmission of a motion picture code in the CIF format is switched to transmission of a motion picture code in the QCIF format in accordance wi
Adams Russell
Ando Electric Co. Ltd.
Fish & Richardson P.C.
Smith Arthur A
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