Science Interviews

Interview

Tue, 19th Nov 2013

Restoring Doctor Who

Paul Vanezis, BBC, and Peter Crocker, SVS

Listen Now    Download as mp3 from the show Restore, repair, retain!

When the BBC recorded over old video tapes, many episodes of Doctor Who were lost.  Earlier this year, 9 missing episodes of the classic sci-fi series from 1960s were found restored at a Nigerian TV station.  Kate Lamble met Tardisproducer Paul Vanezis and Peter Crocker, video restoration specialist, who put them back together. She first asked, what  condition would you expect to find film in after so many years?

Paul -   If the conditions are actually perfect, then the films will be as good as when they're originally made, but we donít live in a perfect world. Sixteen-millimetre film is what weíre talking about. The first issue that you've got is, they were scratched and they had cuts in them where broadcasters had to put commercials in and then remove them again. The glue and the tape was drying out. On the emulsion side, it reacted with the emulsion and had gone very sticky.  That glue was seaping on to that film and discolouring the film. The other problem that we have goes back to the Ď40s. I guess actually, it goes back from way before that when film was on nitrate stock and nitrate was very explosive. So then, Kodak and various other film manufacturers got rid of nitrate because it was basically dangerous and created safety film, a cellulose acetate film. This is the film which is now causing these problems because if itís stored in humid, warm conditions, the acetate in the film starts to break down and it basically leeches acetic acid. This acetic acid gives you this characteristic of vinegar smell coming from the film. The film goes from being a bit smelly to Ė in really bad situations - it will either plasticise, so it will leech out the acid into the emulsion and then the whole thing becomes a soup, or it will shrink. And the emulsion which is gelatine sitting on the surface of this acetate base, gelatine doesnít shrink, but the base does. And so, the whole thing separates apart and you've got an unplayable film.  The problem with these films is, if we put them on a telecine machine to transfer them as soon as we got them out of the cans, they would've just fallen apart on the machine. So principally, what weíre doing here is, weíre not trying to restore the physical film. Our ultimate intention is to restore the image.  And so, once the film leave my hands, they're wound off and within minutes, they're transferred in high definition. Then once itís in a form that we can work with, that's the point where the actual image restoration begins.

Kate -   One of the newly restored Doctor Who episodes was The Web of Fear, featuring one the iconic antagonist of the Patrick Troughton era, the yeti. In the story, the doctor encounters these hairy robotic monsters on the London Underground. So, I was alarmed to hear that I was going to have to head on to the Central line to meet the digital restoration expert who Paul passed the footage on to. I mean, I think this carriage is clear of yeti.

Peter -   I'm Peter Crocker and I'm a Video Restoration Specialist at SVS. I take the high definition video files, load it on to my computer system and then I can start getting rid of dirt, scratches, generally manipulating the image because itís all 1s and 0s, and pixels at that stage.

Kate -   Why do you want to in HD?  The original Doctor Who presumably wasnít in HD.

Peter -   While the underlying image is quite low resolution, the actual dirt is there in very high definition.  Now, if we were to scan just in a normal television definition then a scratch might be one pixel wide and the underlying image might be crossing through very fine details Ė someoneís eye ball or someoneís hair.  To remove that scratch without leaving obvious mark behind is very, very difficult.

Kate -   So, the HD is to see the dirt rather than the original image.

Peter -   That's absolutely right, yes.

Kate -   Can we see one of these pictures, how it came to you?  What does it look like, something 30 years old when it first turns up?

Peter -   I've got a bit here which is a film clip of a helicopter landing in a field.  If I play it, the image is actually very unstable. Itís jittering up and down like mad, a little bit from side to side. There's an awful lot of dirt on it. There's black flashes across the screen which is where the video tape was worn.

Kate -   It sort of looks like those antique photographs. What has that been impacted by?

Peter -   Itís a combination of things.  Some of the problems with the picture were there actually at the time and itís part and parcel of what people would have accepted on their television.  A lot of the damage that we see on programmes of this age is just wear and tear.  There's a little bit here where there's been a splice and a couple of frames are really, very badly damaged.  They, for example, would have to be completely replaced by CGI.

Kate -   So, how did you get rid of this? Do you have to go around taking each of those pixels like you would on Photoshop and erasing them?

Peter -   It is possible to do that if itís a small area affected.  But often, there are problems with the geometry changing as well because the whole film has warped.  In those cases, we employ slightly more clever techniques, really, and that involves analysing the motion of individual pixels from surrounding frames. By actually assessing the motion of each individual pixel in the image, you can map where they would be in the missing frames and you can actually generate completely synthetic replacements. But weíll also use the same techniques of motion analysis to get rid of instability in it. So, we mentioned earlier the jitter of the film and after itís been fixed, running there now, all the jitterís gone and itís rock solid.

Kate -   Can you show me how you'd get rid of a particular scratch for example?

Peter -   So, what we have here is a computer programme called DIAMANT Ė one of several restoration software packages which is available. What weíre looking at now is quite a severely damaged section of an old Doctor Who episode, where the tape was very badly scratched.  This wouldíve been seen on the original broadcast Ė lots of long black lines and many, many white dots and lines that are darting about.

Kate -   You're sort of hoping through here, frame by frame.  Is this restoration that you have to do frame by frame?  Is that how long it takes?

Peter -   For this sort of damage, yes.

Kate -   If you're going through frame by frame with something that's as seriously damaged as this, how long does it take to do one episode then?

Peter -   Well these are 25 episodes and each episode took about 2 weeks to repair.

Kate -   So, do you end up knowing the entire episode frame by frame by the end of those couple of weeks?

Peter -   Itís an odd situation. There are some programmes where, because technology has moved on and maybe restored them 12 years ago and then will come around again. There have been a couple of occasions where I donít actually remember the programme, but Iíll suddenly see a bit of dirt and say, ďI remember that bit of dirtĒ which just shows what a bizarre thing the human brain is.

Kate -   Yes, definitely. Weíve just looked at these white dots and weíve managed to remove 5 or 6 and improve one of these frames in a couple of minutes here.  How satisfying is it to see the end result and say, ďOh!  I've cleaned up all of thatĒ?

Peter -   When you compare the original...

Kate -   So, this is the original with all the dots.

Peter -   With all the dots. Itís not really wonderful.

Kate -   Itís so distracting watching it because you end up watching the dots move around rather than the people.

Peter -   Exactly.  Itís not adequate.  So, after itís been repaired, itís...

(Video playing)

Peter -   You're just watching the programme.

Kate -   Itís completely transformed from watching the faults to watching the programme. I suppose that's what you want in the end.

Peter -   Yes, that's right.  I likened myself to being a window cleaner.  I donít actually make the view any different, but hopefully, itís a nicer experience for someone looking at the view because they're not spotting the dirty window anymore.

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