Film-out
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Film-out is the process in the computer graphics, video and filmmaking disciplines of transferring images or animation from videotape or digital files to a traditional celluloid film print. Film-out is a broad term that encompasses the conversion of frame rates, color correction, as well as the actual printing, also called scanning or recording.
The film-out process is different depending on the regional standard of the master videotape in question - NTSC, PAL or SECAM - or likewise on the several emerging region-independent formats of high definition video (HD video); thus each type is covered separately, taking into account regional film-out industries, methods and technical considerations.
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[edit] Film-out of live action video
Many documentaries and low budget films are shot on videotape or other digital video media instead of film stock, and completed as digital video. Video production means substantially lower costs than 16mm or 35mm film production on all levels. However, the relatively low cost of video ends when the issue of a theatrical presentation is raised, for which a print is required for film projection.
[edit] Standard definition (SD) video
Film-out of standard-definition video -- or any source that has an incompatible frame rate -- is the up-conversion of video media to film for theatrical viewing. The video to film conversion process consists of two major steps: first, the conversion of video into film frames which are then stored on a computer or on HD videotape, and secondly, the printing of these digital film frames onto physical 35mm film. To understand these two steps, it is important to understand how video and film differ.
Film (sound film, at least) has remained unchanged for almost a century and creates the illusion of moving images through the rapid projection of still images, "frames", upon a screen, typically 24 per second. Video (traditional interlaced SD video, anyway) has no real frame rate, (though the term "frame" is applied to video, it has a different meaning). Instead, video consists of a very fast succession of horizontal lines that continually cascade down the television screen - streaming top to bottom, before jumping back to the top and then streaming down to the bottom again, repeatedly, almost 60 alternating screen-fulls every second, or exactly 50 such screen-fulls per second for PAL. Since visual movement in video is infused in this continuous cascade of scans lines, there is no discrete image or real "frame" that can be identified at any one time. Therefore, when transferring video to film, it is necessary to "invent" individual film frames, 24 for every second in time. The bulk of the work done by a film-out company is this first step, creating film frames out of the stream of interlaced video.
Each company employs its own (often proprietary) technology for turning interlaced video into high resolution digital video files of 24 discrete images every second, called 24 progressive video or 24p. The technology must filter out all the visually unappealing artifacting that results from the inherent mismatch between video and film movement. Moreover, the conversion process usually requires human intervention at every edit point of a video program, so that each type of scene can be calibrated for maximum visual quality. The use of archival footage in video especially calls for extra attention.
Step two, the "scanning" to film, is the rote part of the process. This is the mechanical step where lasers "print" each of the newly created frames of the 24p video stored on computer files or HD videotape onto rolls of 35mm film.
Most companies that do film-out, do all the stages of the process themselves for a lump sum, which can range anywhere from about US$30,000 to $60,000 for a feature length film. The job includes converting interlaced video into 24p and often a color correction session - (calibrating the image for theatrical projection), before scanning to physical film, (possibly followed by color correction of the film print made from the digital intermediary) - is offered. At the very least, film-out can be understood as the process of converting interlaced video to 24p and then scannning it to film.
[edit] NTSC video
NTSC is the most challenging of the formats when it comes to standards conversion and, specifically, converting to film prints. NTSC runs at the precise rate of 29.97 video "frames" (consisting of two interlaced screen-fulls of scan lines, called fields, per frame) per second. In this way, NTSC resolves actual live action movement at almost -- but not quite -- 60 alternating half-resolution images every second. Because of this 29.97 rate, no direct correlation to film frames at 24 frames per second can be achieved. NTSC is hardest to reconcile with film, thus motivates its own unique processes.
[edit] PAL and SECAM video
PAL and SECAM run at 25 interlaced video "frames" per second, which can be slowed down or frame-dropped, then deinterlaced, to correlate "frame" for frame with film running at 24 actual frames per second. PAL and SECAM are less complex and demanding than NTSC for film-out. PAL and SECAM conversions do agitate, though, with the unpleasant choice between slowing down video (and audio pitch, noticeably) by four percent from 25 to 24 frames per second in order to maintain a 1:1 frame match, slightly changing the rhythm and "feel" of the program; or maintaining original speed by periodically dropping frames, thereby creating jerkiness and possible loss of vital detail in fast moving action or precise edits.
[edit] High definition (HD) digital video
High definition digital video can be shot at a variety a frame rates, including 29.97 interlaced (like NTSC) or progressive; or 25 interlaced (like PAL) or progressive; or even 24 progressive (just like film). HD, if shot in 24 progressive, scans nearly perfectly to film without the need of a frame or field conversion process. Other issues remain though, based on the variety of resolutions and compression schemes that exist in the high-defintion video world.
[edit] Film-out of computer graphics and animation
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[edit] Film-out of images for the graphic design and print industries
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[edit] See also
- Film recorder
- Film scan
- Tape-out
