American Cinematographer - July 2007 - 81

has the effect of magnifying the noise and so increasing signal-to-noise ratio of the encoder input. Noise is exactly what you don’t want to feed into MPEG4 codecs, which are based on DCT blocks and interframe and intraframe compression. This process is susceptible to “grain” noise, as it can be interpreted as high-frequency image content, and thus wastes valuable bits. Movies are coded for theatrical exhibition using a totally different process, with 4:4:4 sampling of XYZ color space and wavelet-based JPEG2000 compression that is only intraframe. In this case, some grain is often desirable to suggest a filmic look. The upshot is that the grain, or noise, management of a “film” master will have to be revisited to further reduce its appearance and create a clean, crisp look on video discs and in transmissions. That process is best done before grading — effectively pushing the grain management up the workflow to before the grade. Another consideration is the quality of images on different types of screens. The appearance of grain noise and blocking artifacts on CRT screens differs from that on LCDs. CRTs are becoming much less available, and the public is switching to LCDs. The 8-bit digital system of LCDs means that LSB (Least Significant Bit) noise (a truncation of pixel color information values when downconverting from 10 bits to 8 bits), especially in blacks, is more apparent than when viewing the same material on CRTs. Also, computer-generated images with smooth surfaces may show banding errors. With CRTs, the minute inaccuracies introduced by analog noise and the smearing effect of the analog device as it scans actually enhance viewing by randomizing the LSB truncation and so smoothing its appearance. Such noise could help reduce the digital noise noticeable in dark picture areas on LCDs. It would seem that LCD displays would benefit from the introduction of a degree of non-coherent noise that is “friendly” to the encoder to reduce the visibility of LSB truncation effects and blocking. Although there are no technical problems associated with reducing image size to fit smaller screens, there is often also a requirement to change the visual emphasis, especially for very small displays used for mobile viewing. When the picture is so small, it’s necessary to apply stronger vignettes and more of them to draw the viewer’s eyes to key characters or action. A creative grade different from the cinema grade might be required for the DVD version, which is generally viewed in a living room with much higher ambient light than a cinema. To compensate for the viewing conditions, the TV grade involves lifting the darker scenes. Typically this takes one to five days for a feature-length project. Different audiences might require or be delivered different versions of the production. This may involve straight cutting, in which case it may be possible to work directly from the universal digital master, but in many cases it will not. In the search for new revenue streams, product placement is increasingly used. The brand that is to be shown may vary according to the location of the audience; for example, the logo on the fin of an aircraft might have to be changed. Clearly, this would require going back the original material and reassembling it with the new logo added to an original, or pre-prepared, blank fin. Then the scene must be reinserted into the film. Some material included in the universal digital master might not be acceptable in some countries, or two versions might be required, one for family viewing and the other to be shown after the “watershed” hour. In either case, this will require further editing, and the people doing this work will probably work from the source material and reassembly. If making cuts or changes to the images, work on the audio must follow. This may require access to the source audio to correctly rebuild the tracks so that they again fit with the onscreen action. Digital Multi-Masters Clearly, there are ample grounds for seeking a new post workflow and producing a new type of master. This Fluid thinking. Watertight solutions. We have an extensive inventory that includes 435 and 35-3 Remote AquaCam™— 2001 winner of a Technical Achievement Award from The Academy of Motion Picture Arts & Sciences • • HD Remote AquaCam™ • Underwater camera housings • Splash bags companion • HydroHead ®— the perfectand splash bags to our RemoteAquaCam • Light meter housings • Underwater lighting — including HMI, incandescent, fluorescent & ultraviolet • Ground Fault Protection ™ for a full range of tilts and pans, in, out and over the water — now available with a third axis for even more range of motion 5335 McConnell Avenue Los Angeles, CA 90066 Tel: 31 0/301-8187 Fax: 310/821-9886 www.hydroflex.com 81

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American Cinematographer - July 2007

Table of Contents for the Digital Edition of American Cinematographer - July 2007