Computer graphics processing and selective visual display system – Computer graphics processing – Adjusting level of detail
Reexamination Certificate
2001-03-16
2004-12-07
Nguyen, Phu K. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Adjusting level of detail
Reexamination Certificate
active
06828967
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of and apparatus for digital data storage.
BACKGROUND OF THE INVENTION
The growing importance of digital media places increasingly severe demands on the resources within a distributed system, particularly as regards network bandwidth and data storage. Faster client and server systems and increasingly large and sophisticated media files lead to increased expectations by users of being able to access and manipulate these files easily. Whilst bandwidth issues receive much attention from the designers of the systems that handle digital media, the high cost of storing digital media is becoming significant, despite the falling costs of many kinds of storage.
The traditional approach to reducing digital media storage costs is to migrate little used material from on-line delivery platforms, such as the hard drives of PCs and servers, onto lower cost archival storage, such as tape. The cost and delay in retrieving such archived media and delivering it on-line can be quite considerable, however. This cost is becoming increasingly apparent to system designers.
Another approach to reducing data storage costs is to retain digital data within the on-line delivery system, but to compress it. Compression technology can significantly increase the amount of material available on-line, but may degrade the material and thus imposes a uniform level of quality. This may be below the minimum quality threshold for some users. It is not always possible to know a priori the requirements of all the users for the media and conventionally there is no mechanism for recovering quality once it has been lost. Hence, traditional compression approaches are inherently limited.
One of the problems of compression schemes is that they take no account of the varied and possibly conflicting requirements made upon the media by the shared access of multiple clients. Most compression schemes utilise an “all-or-nothing” principle: until the media is completely delivered and fully decoded, the user cannot browse or examine it in order to decide whether it is what they wanted. If not, then there is no option but to discard it completely. This is obviously an inefficient use of resources.
Recent work has concentrated on improving the usability of media over networks, and reduce inefficient use of network resources, by introducing “progressive” compression schemes
One such ‘progressive’ scheme is disclosed in U.S. Pat. No. 5,880,856 to Microsoft Corporation, which teaches a particular approach to the use of wavelet transforms. In the U.S. Pat. No. 5,880,856 patent, an image is transformed using the wavelet transformation to yield 4 or 5 decomposition levels, with a base decomposition level giving a low resolution image, and increasingly higher decomposition levels giving higher resolution images. The client receives initially only the base decomposition level data, but the low resolution image resulting from the base decomposition level data gradually sharpens up as higher decomposition levels are received and decoded. Sharpening up of the image occurs as a result of 2 factors: first, as all of the 4 sub-bands which form each decomposition level are received and decoded, the image quality level increases slightly. As successive decomposition levels are received and decoded, the image quality increases more significantly. One characteristic of the system taught in the U.S. Pat. No. 5,880,856 patent is that the sub-bands and decomposition levels are all transmitted to clients in the same, fixed order, which is relatively inflexible. Whilst this scheme allows the client control over quality, it provides no other parameters that can be controlled.
Further reference may be made to the paper by Beong-Jo Kim, Zixiang Xiong and William Pearlman, “Very Low Bit-Rate Embedded Coding with 3D Set Partitioning in Hierarchical Trees”, submitted to IEEE Trans. Circuits & Systems for Video Technology, Special Issue on Image and Video Processing for Emerging Interactive Multimedia Services, September 1998. This paper discloses applying a SPIHT compression scheme to a wavelet-based transform, which yields a bitstream encoding multiple spatial resolutions, with progressive quality ordering within a given spatial resolution, as in the U.S. Pat. No. 5,880,856 patent.
Another system for scalable video transmission is disclosed in U.S. Pat. No. 5,768,535 “Software-based encoder for a software-implemented end-to-end scalable video delivery system”. Here, the scalable property of a hierarchical image decomposition, similar to the wavelet transform, is used in conjunction with vector quantisation to produce a stream that scales in spatial and temporal resolution. At the receiving end the decoder extracts a stream with the required spatial and temporal properties. Full resolution, full frame rate images can be migrated from disk to CD-ROM to tape as they age, but can be recalled if needed.
A similar system is described in the JPEG 2000 image coding system draft specification (ISO/IEC CD15444-1: 1999). This describes a coding method for still pictures using a wavelet transform in conjunction with coefficient significance-ordering in a manner similar to the SPIHT system described above. Markers are inserted into the bitstream to allow the decoder to extract a reconstructed image of the desired quality.
Yet another approach is disclosed in U.S. Pat. No. 5,953,506 “Method and apparatus that provides a scalable media delivery system”, which describes a system for encoding multimedia data in MPEG format as a base stream and a set of additive streams that can be combined to provide various quality levels to satisfy the requirements of different clients. The invention adapts to changing network bandwidth by adding or removing streams, according to a Client-provided profile, and so increasing or reducing bit-rate. It is designed to satisfy a straightforward streaming model of media delivery, where a media steam is produced by the Server and consumed by the Decoder.
The five prior art disclosures described above are designed to present media to a client over a network in a more user-friendly manner than previously, removing, to some extent, unacceptable delay due to the properties of the network. They are not designed from the point of view of a storage system, neither do they present a view of the underlying structure of the file that would allow a storage tool to determine how to degrade quality in a controllable way.
They are also specific to particular media encoding formats, in that the tools that manipulate the media in the quality domain need to know the details of the encoding scheme in order to function. Most importantly, such tools cannot be made to be independent of encoding format, and to work correctly with any media file with any media encoding.
To do these things knowledge is required of the way that a component of the media depends on other components, in order for decoding to be possible.
New systems for media manipulation require more flexibility as regards access and retrieval of material in the storage hierarchy. Such systems must be capable of the following:
Randomly to access any component of the media, where a component can be a time-ordered sequence of media parts, a media part sampled at a particular time, a spatial area within a media part, a colour within a media part, or any other aspect which can be described.
To access the above components at a quality, spatial resolution or frequency resolution specified by the client.
To allow the results of any such access to be refined in such a way as to increase the information content and consequently improve the visual quality, amount of detail, or other aspect, of the material.
To perform the above operations using format-independent tools.
In order to satisfy the requirements listed above a system is required for structuring media files of any type for the maximum flexibility of access of their constituent components.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, there is provided a method of storing digital
Cole David John
King Tony Richard
Internet Pro Video Limited
Nguyen Phu K.
Rosser Roy
Synnestvedt Lechner & Woodbridge LLP
Woodbridge Esq. Richard C.
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