When scanning film material, two methods can be used. Dry scanning (known as ‘drygate’) and wet scanning with the “Schmitzer wetgate method”. Dry scanning is the standard method when the material is intact, while wet scanning using a perchlorate solution is deployed for damaged film material. In the latter process, the perchlorate solution occludes or smoothes over cracks and holes in the material during the wet scanning.
Preparation and standards
- The first step involves deciding, based on the condition of the material, whether to proceed with dry or wet scanning.
- Prior to scanning, we test to ascertain what type of film and accompanying sound is present (film + cord strip, film + optical sound, film + optical sound + cord strip; film with edge track magnetic sound, film with edge track magnetic sound + cord strip). Based on the sound type, tests are carried out to ascertain which soundtrack will elicit the optimal qualitative results.
- The cord machine (MB51 film deck) is configured with a standard per tape rule. As w tape rule reference, we use an original magnetic sound sensing film complying with the SMPTE standard.
- We avoid the use of filters (including film contamination and scratch filters) where possible. However, if the client would like them used, we pay special attention to avoid any filter-related leftovers.
The scanning process
- The scanning process is optimised such that the Fixed Pattern Noise (FPN), namely the so-called screen door effect – SDE attributable to specific device settings is avoided.
- To monitor the video signal and avoid excess attenuation, we use a legaliser system, which detects illegal colour values during the scanning process, and displays and corrects the same. Here likewise, our full attention is devoted to avoiding any unwanted leftover traces.
- Using the film scanner, we can apply the following forms of correction during the scanning process for the visual qualities: contrast, colour, brightness, gamma and black stretch.
- With the basic correction of the image parameters of the scanned film, we ensure that we retain access to the full contrast range of basic materials.
- Parameters such as film grain, noise reduction and contract enhancement can also be configured. We confer with the customer when making these decisions.
- During the playback process, we check the image and sound quality visually as well as acoustically with the appropriate control instruments.
- For checking video information, a rasteriser (vetorscope and a waveform monitor) are used, and audio signals are checked via a RTW master monitor showing the peak metre and the correlation grade indicator.
Storage of data on data media
- The information in digital form, which the film scanner generates as a component data stream, is stored on a hard disk at the NLE editing desk (using AVID Media composer).
- Film and sound data are present after the playback process in transparent form (uncompressed and at maximum possible quality) as separate data streams on data carriers.
To ensure optimal results during the film scanning process, the following work is regularly carried out by our specialist employees:
- Cleaning of the projection lenses of the scanner (several times daily)
- Checking of the sealing joints and weekly maintenance of wetgate
- Inspection of the device room/workspace and the sealed perchlorate circuit during wetgate operation in accordance with the legal regulations specified in the Federal Emission Protection Law (German Civil Code. I p. 3830) by constant measurements conducted at 4 separate measurement points via appropriate gas photometers.
- FPN self-correction of the scanner by avoiding FPN (min. 3x daily, inc. white balance).
- Inclusion of the warm-up phase for the scanner and cord machine (for stability and synchronisation, calibration), when these have been turned off (significant maintenance, repair etc.)
- The projection lamps of the scanner are checked and regularly replaced using time counters and FPN evaluation of the blue light portion.
- Ensuring uniform ambient temperature for the entire set of scanning equipment via the use of air-conditioners.