Television – Monitoring – testing – or measuring – Transmission path testing
Reexamination Certificate
1999-09-24
2002-04-09
Hsia, Sherrie (Department: 2614)
Television
Monitoring, testing, or measuring
Transmission path testing
C348S553000, C348S559000
Reexamination Certificate
active
06369852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an analytical system for moving picture regeneration, and more particularly, to an analytical system for evaluation of a regeneration unit for regenerating digital data of a moving picture.
2. Description of the Related Art
Following an advance in enhancement of the processing speed of computers, fast transmission via a network, and enlargement in the capacity of memory media, a practice of regenerating a digital moving picture and utilizing the same has been in widespread use. The digital moving picture is made up of a sequence of instantaneous images, called frames, and each of the frames consists of digital data representing both color and brightness of each of a multitude of points, called pixels or dots, that are obtained by subdividing a picture on a display unit in grid-like fashion.
About 10 to 20 or more frames per second are needed to enable the human visual system to perceive smoothness in variation of images, and about 50,000 to 100,000 or more of dots are needed within a picture in rectangular form to obtain resolution comparable to that of a moving picture broadcast by the conventional television system or the like while tones on the order of about 200 are needed to enable the human visual system to have a feeling of natural tone appearing on a conventional display unit. In the case of full-colorimages, such moving picture data as above are required for each of the three primary colors. In this case, information throughput amounts to about 10 to 100 Mbits or more per second. Accordingly, information throughput of moving picture contents for about 30 minute duration amounts to from 50 to 500 Mbytes, which is quite massive in comparison with audio data, document data, and so forth.
Consequently, a bit stream obtained by compressing the information throughput, called moving picture code, is employed for the moving picture data, and the moving picture codes are used in communications media and memory media. More specifically, the dot data of images generated by a camera and the like are compressed by a unit called a moving picture code encoder (hereinafter referred to simply as an encoder), thereby generating once the moving picture codes, which are then stored in the memory media by use of a semiconductor memory, a fixed disk unit, an optical disk unit, a magnetic tape storage, and so forth. Or the moving picture codes obtained are transmitted via communications media such as telephone circuits, a local area network (otherwise called LAN), and so forth.
On the other hand, for viewing an original moving picture by use of the memory media in which the moving picture data are stored, use is made of a unit for fetching the moving picture codes out of the memory media, and a decoding and regenerating unit (hereinafter referred to simply as a regeneration unit) for decoding the moving picture codes into original dot data and displaying the same on the display unit. Meanwhile, for viewing the original moving picture upon receiving the moving picture data transmitted via communications media, use is made of a receiver for receiving the moving picture data, and a decoding and regenerating unit (hereinafter referred to also simply as a regeneration unit), the same as described above, for decoding the moving picture codes into the original dot data and displaying the same on the display unit.
There are international standards for moving picture coding systems, for example, MEPG-1 (ISO/IEC01172), MEPG-2 (ISO/IEC 13818), and MEPG-4 (ISO/IEC 14496), in accordance with International Organization for Standardization (ISO) as well as International Electrotechnical Commission (IEC), and H261, H263, and so forth recommended by International Telecommunication Union (ITU). With these systems, a compression ratio of information is typically on the order of 1/5 to 1/50 in terms of a ratio of data throughput after data compression to that before data compression.
With the moving picture coding systems described above, the magnitude of a code amount of respective moving picture codes obtained from the dot data of the same moving picture can be rendered variable. For example, in any of the moving picture coding systems described above, coding is performed by use of a frequency component value of tone values in spatial distribution, called DCT (Discrete Cosine Transform) factor, thereby effecting coding by selecting a quantization (digital coding) step width (coarseness), (hereinafter referred to simply as quantization step width), of the DCT factor from among steps in number ranging from several tens to several hundreds. In this case, the code amount per a unit time is called a coding rate, and the coarser the quantization step width is rendered, the lower the coding rate becomes while conversely, the finer the quantization step width is rendered, the higher the coding rate becomes. That is, as the compression ratio undergoes changes depending on the quantization step width, the compression ratio is rendered variable by effecting coding through selection of the quantization step width. Since the DCT factor represents a spatial frequency component value, a difference between a decoded image and an original image becomes wider by rendering the quantization step width coarser (that is, by raising the compression ratio), and conversely, rendering of the quantization step width finer (that is, lowering of the compression ratio) is equivalent to bringing of the decoded image closer to the original image as faithfully as possible.
An increase in difference of the decoded image from the original image, caused by raising the compression ratio as described above, is called degradation in the quality of the moving picture due to compression. Such degradation can be converted into numbers as follows. First, a differential image composed of pixels obtained by deducting the tone value of respective pixels of a restored image from that of respective pixels of the original image, corresponding to the respective pixels of the restored image, is found. Subsequently, a ratio of the root mean square of the tone value of respective pixels of the differential image against the root mean square of the tone value of the respective pixels of the original image is found This ratio is referred to as a SNR (abbreviation of Signal to Noise Ratio), and used as the degradation described above as converted in numbers. Or the logarithm to the base 10 of the ratio, multiplied by a factor of 10, that is, a value expressed in terms of dB (decibel) is often used. Otherwise, there are cases where in place of the root mean square of the tone value of the respective pixels of the original image, use is made of degradation converted into numbers by use of the square of the maximum amplitude that the tone of the original image can have, specifically called a PSNR (Peak SNR).
In this connection, the differential image used in such conversion is taken as noise caused by data compression. Accordingly, it is defined that the larger the noise, the smaller the SNR is, and the smaller the noise, the larger the SNR is.
Analytical evaluation by use of the SNR is applied to the following as well in addition to the evaluation of the degradation due to data compression. That is, it is applied to evaluation of degradation in picture quality, caused by a transmission error during transmission of the moving picture-codes from communications media and memory media. In case of a transmission error occurring to only a part of the moving picture codes, there will be generated spots where decoding can not be effected in other parts thereof either. An extent to which such an effect ripples through is dependent on either the type of codes to which the transmission error has occurred or the precise mode of coding. The transmission error even by 1 bit can result in inability of decoding in a region covering pixels in number ranging from several tens to several hundreds, or in outputting incorrect tone values decoded.
There is also a method of displaying a picture to cop
Ando Electric Co. Ltd.
Flynn ,Thiel, Boutell & Tanis, P.C.
Hsia Sherrie
LandOfFree
Analytical system for moving picture regeneration does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Analytical system for moving picture regeneration, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Analytical system for moving picture regeneration will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2828876