Behind The Scenes, 22 May 2019: Stabilising film
by James Gibbs, Media Technician
At the Film and Television Archive, we often find ourselves staring at a computer screen whilst a small rectangle bounces about. We’re not playing a retro Atari computer game; we’re using a tracker to track something on some scanned film – this is usually so we can stabilise the film image.
Our film scanner is great at handling film of all types and in all conditions. The film can be very fragile and damaged, and the scanner will treat it with care. The downside of this is that the film often tends to weave about a bit as it is scanned. This ends up as a random motion in the final footage which, as you can imagine, isn’t ideal.
The scanner uses the perforations along the edge of the film to stabilise the image vertically. Often the perforations are damaged or aren’t perfectly locked to the frame and so the film moves up and down from frame to frame ever so slightly.
Many of our films contain splices which can cause the image to shift significantly upwards or downwards just before the cut in the film. On the standard film gates for the scanner there is no edge guide so the film is free to shimmy left and right as it passes through the gate.
All of this means we need to spend some time stabilising the image from the film scans. The software we use has incredibly powerful tracking tools that can be used for all sorts of things.
In feature films it can be used to track an actor’s face to add a bit of brightness to their eyes. In a car commercial it can be used to track the car to give it an extra boost of colour and contrast.
When we use the tracker for stabilisation work, we find something in a fixed position on the film and set the tracker going. Sometimes, this will be the perforations, sometimes it could be a bit of dirt stuck in the gate of the camera when the film was shot, or it could simply be something in shot that doesn’t move. The stabilising effect uses the information from the tracker to keep the tracked item stationary.
The example below is from a superb Westward Television documentary called ‘My Ship, My Parish’. Excerpts of this will feature in The Box’s ‘Port of Plymouth’ gallery.
The film is about the two Chaplains aboard HMS Ark Royal in the early 1970s. This was a film that moved about a lot during scanning, particularly at the splices. We scanned from the A and B rolls which were the cut negatives used to make the final print so every single shot on the film was spliced together. The split screen video shows the ‘before and after’.
In the first shot, the tracker was focused on the railing behind the Chaplain. The remaining shots were moving shots. Fortunately they all had dirt from the camera gate around the edge of the frame which provided us with great points to track.
Stabilising film takes time and a lot of work but it’s worth the effort!