Naked Science Forum
Non Life Sciences => Technology => Topic started by: SquarishTriangle on 02/04/2010 03:54:04
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How do they take old movies on film and make them look all new and shiny again? I have an image of someone sitting at a computer fixing the pictures frame by frame...but that seems a little time consuming.
So how do they do it?
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I would guess that a lot of what they're doing is scratch and speckle removal, but they might also be enhancing contrast and sharpening the images too, by passing each frame through an appropriate graphical 'filter' in a graphical image manipulation program.
Most graphical filters use something called a 'convolution matrix'. Have a look at:
http://docs.gimp.org/en/plug-in-convmatrix.html (http://docs.gimp.org/en/plug-in-convmatrix.html)
to get an idea of how they work.
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If you're genuinely interested in how this sort of thing is done, you might find a browse of the Restoration Team website ( http://www.restoration-team.co.uk/ (http://www.restoration-team.co.uk/) ) quite interesting. The Restoration Team are the team behind the cleanup of all the restored Classic Series Dr Who adventures on DVD. Some of the techniques they've developed over the years are quite fascinating and well worth a read. Try reading the one about 'Inferno' first and then check out the amazing full re-colourisation of an episode from the Dalek War Boxset.
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In traditional (i.e. pre-digital) film-making, the 'print' which you see at the cinema is about a 5th-generation copy of what went through the camera - so potentially has a fair amount of generation-loss even before considering dust and grime picked up in the cinemas, and the fact that the colours tend to rapidly fade in the print during its cinema screenings (hardly surprising since the projector casts 1kilowatt or more of light on each frame for 1/48th (trust me!) of a second in each screening). On relatively modern prints, its the reds/pinks/oranges which fade most rapidly, leaving a somewhat insipid greeny-looking print when compared to a virgin one.
If they're doing a proper job of doing a remastering, they'll often try and go back to some earlier-generation negative, which won't have suffered fading and abuse in the cinema, is probably cleaner, and has more sharpness and contrast-detail to be pulled out. They may well apply some kind of dust and scratch-removal too.
Some high-end consumer film scanners detect dust and scratches by scanning in an infra-red channel as well as the colours you'll see. The information from the IR scan is used to assist automatic blemish-removal. I imagine they can do something similar in professional movie-film scanning - although it's always wise to have a skilled operator oversee the process (if you can afford it) to avoid artifacts.
I second krytie75, and agree that the Restoration Team website is a good read - even if it is more targeted towards old TV/film-for-TV rather than old cinema movies...