What is the best file format? The question is unanswerable in the general case, as the criteria for judging vary greatly according to the intended uses of the data.
Chris suggested that the output from this workshop should be a report that aids users select an appropriate format for their needs, rather than attempting to answer the unanswerable with blanket recommendations which would be inevitably influenced by the small pool of possible multimedia applications that the workshop attendees could collectively envisage.
Certainly there is need in the user population for guidance, but Chris suggested an approach of user education. There are a lot of 'graphics formats' which cause confusion. Let us lessen that confusion by providing a pragmatic classification so that like can be compared with like. Let us explain the factors that affect the choice, the consequences of particular choices, and the influencing factors such as cross platform portability, compliance with international and industry standards, and retention of information during conversion.
Chris noted that when writing the ITTI-funded 'Standards in Computer Graphics' training materials, he found that the ISO Computer Graphics reference Model, then newly published, was an excellent structuring mechanism. In the chapter on Data Capture Metafiles he used the CGRM to classify file formats. Having a good idea of the properties and capabilities of data captured at each environment in the CGRM ensures that users will not attempt to compare, say, IGES with TIFF, or RIB with PostScript. Equally, it explains why converting from CGM to GIF is possible, but involves information loss such that the reverse conversion cannot recreate the original file.
Chris believes that given clear information and a succinct description of the factors affecting the choice, users can then select an appropriate format with some confidence that the selection will be appropriate.
He suggested recommending a strategy of minimising information loss, so that (bandwidth and storage permitting) data is moved and shared in the form that preserves the most information, and down converted locally using recommended procedures. Also, there is a balance to be struck between an optimal file format for a particular situation, as against the growing trend to repurpose images. Again, this comes down to minimising information loss both in the format and in the conversion strategy.
Clearly this general information needs to be balanced by concise description of the capabilities and common uses of particular formats.
So for example TIFF 6.0 is able to hold a great deal more information about an image than, say, Iris RGB, which holds more than GIF. So if the intention is to maximise quality, transfer the images as TIFF and convert down to GIF locally using the NetPBM toolkit. But in some circumstances this is an inappropriate choice, if the intention is to share a library of icon images, TIFF would be a poor choice. If the intent is to provide 600 images on one floppy, it would also be an inappropriate choice.
Another, but related, aspect, is that of educating people with new skills to help them use the new technologies. This again is something which AGOCG and other organisations need to address.
Any report needs to include a glossary.
Graphics Multimedia Virtual Environments Visualisation Contents