Digital Cinema describes the use of movies with a digital data representation in best quality. Traditionally movies are shot on film and projected with film. In the future this will be done with digital cameras and digital projectors. Because of the huge amount of data within this application area data compression will be necessary. In contrast to Electronic Cinema, which uses the digitization of the film for new commercialization pathes, Digital Cinema replaces only the film chain from the acquisition to the film theatres. Therefore Digital Cinema must achieve and surpass today's best film quality. The parameters for the digital representation of the movie have to be much more extensive than in standard videos.
Previous compression standards have different limits for the use in Digital Cinema. This can be the maximum resolution, the compression possibilities (only lossy), the sampling type, the colorspace or the bit depth. Motion JPEG2000 is an excellent compression standard for the use in Digital Cinema, because it delivers enough headroom in the description of digital movie data and has outstanding features, which can be used. Some features of Motion JPEG2000 are intraframe coding for a simple editing access, lossless compression capabilities, metadata insertion, scalability in resolution and quality and so on. All features of the still Image JPEG2000 Standard 15444 - Part1 can also be used.
Requirements in data compression for Digital Cinema include high dynamic range, different color spaces, highest image resolutions, best compression quality including lossless compression, and so on.
With Motion JPEG2000 the following parameters in Digital Cinema are possible, but not limited to:
- Resolutions of 8192x8192 Pixel (e.g. 4096x3112 for 35mm Film Scans)
- Colorspace: sRGB, SRGB-YCC
- Number of color components: 3-4 (e.g. RGBA)
- Bitdepth: 10-16 Bit/color component
- Pixel Sampling: 4:2:2 - 4:4:4
- Compression types: mathematically lossless, visual lossless, lossy
Other requirements for Digital Cinema are the use of sequences with single frame files, synchronisation with audio or metadata descriptions for extended metadata sets. These requirements can all be met. With Motion JPEG2000 a powerful compression standard is ready for use to solve the requirements in Digital Cinema during acquisition, postproduction, archiving and perhaps distribution.
During acquisition the enourmous headroom in the parameters like bitdepth, resolution, colorspace can be used. The insertion of metadata in a MPEG conformant description allows maximal flexibility in the type of metadata. So metadata on film clappers can digitally be carried along with the video data. During postproduction easy access to single frames is possible. Also previews without decoding of all of the file can be done. The compression can be set to lossless to avoid generation losses. This features can also be used in archiving of movie data.
For more details, see:
Powerpoint Presentation "JPEG2000 for Digital Cinema Applications"
Powerpoint Presentation "Motion JPEG2000 and Digital Cinema"
Dr. Siegfried Foessel
Chair of the Dcinema Adhoc Group
Fraunhofer IIS, Erlangen, Germany
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