Film Breath and Gate Weave. Introduction to the new tools

A cinematic image shot on film has some particular attributes that cannot be seen on pause nor noticed within a single movie frame.

These features are mostly related to the mechanical film movement, typical for any device with film transportation — be it a camera, projector or video coding device (telecine or scanner).

Historically, these features were considered artifacts that the industry was struggling with on its way to a high-quality image. With the rise of digital technology, unwanted artifacts turned into highly desired aesthetic effects that are often used to ‘bring life’ into a sterile digital picture.

From a spectator perspective, there are two most important artifacts (or ‘effects’) for creating a ‘living’ cinematic image:

Film Breath

This term speaks for itself and the effect is noticeable as an accidental change in exposure, contrast and colour from frame to frame as the film moves. The nature of this phenomenon is determined by several factors:

  • uneven emulsion coating
  • instability of the camera shutter (shutter speed accuracy)
  • film development deviations (caused by instability of solutions along the entire film length, uneven remjet backing layer removal, etc.)

It will be rather difficult to see any artifacts of Film Breath on modern 35 and 70 mm films shot on top grade cameras (e.g., Arriflex, Panavision), developed and scanned in professional laboratories with strict adherence to all production processes. However, they are still present in small amounts, and in one way or another they affect the viewers’ experience.

If the film is expired, or the movie is captured on a basic or older and worn-out camera, along with poor development, the artifacts of Film Breath are likely to be more visible.

Film Breath artifacts are most pronounced on Super 8 film, even if it’s fresh and well developed. This is because the smaller the frame size, the stronger is the appearance of even minimal (within the technological tolerance) irregularities in emulsion coating. In addition, Super 8 films are usually shot on amateur cameras with simplified design.

To mimic the Film Breath phenomenon in Dehancer OFX plugin, we implemented the special toolset with the same name.

The Period parameter determines the number of frames within which colour, contrast and exposure varies. The larger this value is, the smoother are these fluctuations. With smaller values changes occur faster and are more ‘jerky’.

The Exposure, Tonal Contrast and Color parameters determine the amplitude of fluctuations. With greater values, the corresponding variations will be more pronounced.

The Color parameter defines the amount of colour shifts, based on subtractive transformations. This effect is similar to the CMY Color Head tool, but within the Film Breath it’s controlled with random values.

Impact adjusts the overall effect. When Impact is reduced, all changes in colour and exposure are reduced altogether and vice versa.

Gate Weave

This is a commonly used term that refers to the mechanical swinging of a film strip while it is being pulled through a frame window in a film camera, projector or video coding device.

High-end cameras, projectors and scanners make it possible to position and stabilise the film quite accurately as it moves. With such devices, the Gate Weave effect will be subtle, but it is usually still present and subconsciously affects the perception.

After scanning, the film is usually software stabilised, thus greatly mitigating the fluctuations of Gate Weave.

However, sometimes the stabilisation step is skipped or performed in a ‘lighter’ manner to preserve the natural ‘breathing’ of mechanical movements.

Digital cinema is lacking the natural artifacts of Gate Weave, so it is often simulated intentionally to ‘breathe life’ into a synthetic image.

Gate Weave is most evident when the mechanical components of a camera or projector are imperfect. This is particularly noticeable in old movies (see, for example, Charlie Chaplin), as well as with amateur Super 8, 8 and 16 mm cameras. The Gate Weave artifacts also become more prominent when the old film with worn perforations is reeled in.

The Period parameter determines the number of frames within which mechanical frame shifts occur. The larger this value is, the smoother are the ‘bumps’ during playback. With smaller Period mechanical shifts occur faster and the ‘film’ yaws more jerkily.

The Translation parameter specifies the amplitude of random shifts in the frame plane (both horizontal and vertical) in conventional units.

The Rotation parameter sets the maximum angle of random frame rotation in relative units.

The Auto Zoom parameter automatically zooms the image in to crop any black gaps left on the screen after the geometric offsets occur.

Within the Gate Weave tool the Impact parameter adjusts the overall impact factor, not the ‘opacity’ of the effect. When Impact is reduced, all shifts and geometric distortions in the frame are proportionally reduced, down to zero.

We have a special demo of Film Breath and Gate Weave tools in action:

Please note that for illustrative purposes, both tools are set sometimes to the extremely large values. In real practice, much more delicate settings are usually required to ‘bring life’ to the footage.

Thank you for your attention. We look forward to hearing from you and always ready to answer your questions.

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