2.  Some MPEG-7 Issues

Some issues arising out of or related to scope, applications and MPEG-7 related technology are listed below.
 

• Scope An appropriate interpretation of the scope, more in the spirit that in a literal sense. The interpretation has to keep in view the needs of a wide variety of applications as well as what is feasible and practical. MPEG-7 does not aim to standardize the search engines or feature extraction engines but only the "content description". A simple, concise and desirable scope statement. Can we achieve inter-operability of search engines by standardizing only content descriptions? If we do not specify what results a search engine or filter agent should produce given a description, what level of inter-operability do we achieve? If we specify what the search engine should produce given a description, then we have standardized the function of search engine. It appears to the author that this need to be done. However, this does not mean that the procedure of the search engine is standardized. There is still scope for competition. A closely related concern is whether all desirable features can be represented independent of their extraction algorithms or their corresponding search techniques. Can MPEG-7 provide a successful solution to the industry if such features are eliminated? Probably not. It appears that the effort should be to exclude such features, but if some such feature presents a strong case for inclusion it has to be included.  The performance related requirements poses another difficulty for the scope as well as test and evaluation procedures. "MPEG-7 descriptions should support fast and accurate content based retrieval" is a requirement without which the very purpose of MPEG-7 may be questioned. However, the speed and accuracy of the retrieval would depend on the search engine, search strategy (as in combining different attributes to form a composite query) and last but not the least the database which stores the descriptions. None of these are within the scope of the standard. Does it mean that the standardization process should not take into account the speed and accuracy issue ? Is there a compromise staying within the scope and not interfering with the search, feature extraction or database.

• Applications Categorizing the applications and identifying the requirements imposed on MPEG-7 by the applications. There are two aspects here. The first is to decide on a set of core applications which will drive the standards. Then there are other applications which are enabled by MPEG-7. For example there is a distinct difference between video on demand systems and visual control systems. It is ideal if both these applications impose same requirements on MPEG-7. However, if they do impose conflicting requirements (which is quite likely), then a choice has to be made. In this specific example, it is my view that video on demand may be the choice over visual control. The second aspect is the issue of deciding which requirements of the application should MPEG-7 standard satisfy. This is related to the scope issue and leads to those discussed in section above.

• MPEG-7 Technology Last but definitely not the least, is the technology required for MPEG-7's success. We need several categories of technologies and tools. Description generation tools which can automate or reduce the manual effort in generating the descriptions are essential to the success of MPEG-7. Without efficient search engines MPEG-7 descriptions will serve no purpose. It is also important to go beyond search and retrieval. This is an are which is open and much research is required. The printing community's lead in repurposing using asset's in an asset management system may be one way to proceed.

3. Conclusion

In this article, some issues arising out of the MPEG-7 scope statement is introduced. Many of them have to be carefully considered and answered before MPEG-7 standard materializes. It is the view of the author than technically acceptable compromises keeping in view the current state of the art is inevitable.