Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!dimacs.rutgers.edu!aramis.rutgers.edu!ibm-b.rutherford.ac.uk!CDO From: CDO@ibm-b.rutherford.ac.UK (Chris Osland) Newsgroups: comp.graphics.visualization Subject: Re: free video movies Message-ID: <9103190446.AA14932@psi.rutgers.edu> Date: 18 Mar 91 11:49:10 GMT References: Sender: nobody@aramis.rutgers.edu Lines: 89 On 15 Mar 91 18:39:11 GMT Lenny Tiefel said: > >The Eastman Kodak Research Laboratories will be generating >video movie sequences and providing these freely through >anonymous ftp within the next three months. (The details >will be given later.) > >So, to provide the world's research community with the most >useful images, consider the following questions: > > >What image format would be most useful? >Example: gif ISO standard 8632 (Computer Graphics Metafile) provides for all conventional graphical primitives, is self-contained and self-describing and we have used it for the production of videos that have been used by scientists and broadcasters for some years. CGM includes Cell Array, which may or may not map 1-to-1 onto a pixel array. > > >What image size (pixels, lines, bands) >would be most useful? >Example: 256x512x3 > If the pictures are stored as Cell Arrays in CGM, the intended aspect ratio and the resolution of the picture is stored as part of the CGM and so the picture can be correctly scaled onto any physical device. It can also be anisotropically stretched to fill a screen or to save resampling the image. > >Would monochrome be more useful than color? > No. > >How many bits per pixel would be most useful? >Example: 12 > 8 bits/pixel/colour is easiest to process if representing RGB; standard digital TV (in CCIR 601 4:2:2 coding) is 8 bits for each component (Y, U, V in UK; possibly called Y, I, J in US?) but with colour difference only stored for every other pixel. If the suggestion of 12 is bits/pixel (so 4 bits/pixel/component) I would say that is much too few - coarse colour changes will result. Minimum 6 per component. > >Would computer generated motion drawing >be more useful than actual video movies? > No comment. > >What sort of scenes would be most useful? >Example: a moving car > For the research community I would have thought a mixture of ordinary images (as per moving car) and scientifically oriented images (eg views of a sculpture rotating on a pedestal, rocket motor firing) would both be useful. > >How many frames per scene would be most useful? >(Assume 24 frames per second.) >Example: 100 I am intrigued that the suggestion is that of a film, not a video, frame rate. 100 frames seems fine. CGM (see long way above) provides run length encoding as standard for call arrays and this can often provide a factor of 20 or so compression on computer generated pictures. Because of noise, compression of camera-captured pictures is not so good. Chris Osland Headof Computer Graphics Rutherford Appleton Laboratory Chilton, DIDCOT, Oxfordshire, UK OX110QX Tel +44 235 44 6565 Fax +44 235 44 5808