BBC R&D attempting recovery of decomposing film

Discussion in 'Visual Arts' started by jtiner, Jan 1, 2018.

  1. JohnO

    JohnO Forum Resident

    Location:
    Washington, DC
    I also don't really understand why they had to cut the film. The article is not showing what I want to know.

    They should be scanning from the side of the film pancake, making like 1,000 virtual slices of the whole pancake, to assemble later by computer. If they can't do the whole pancake at once (apparently not?), they could do 1000 slices of every 1cm x 1cm section of it, or even every 0.5cm x 0.5cm section of it, each slightly overlapped with adjacent sections, without ever cutting the pancake. It's possible they are scanning from the side, there's a reference to "scan slices" but that could be either way, but it is really hard to tell from the descriptions and the figures shown, and I did not pick up a good reason why they had to cut the film.

    I've had CT and MRI scans and they did not cut me into 1 cm cubes to do it. But those were much lower resolution.

    (I also picked up the typo of "wnwarp" on the Part Two page, I did read it all very carefully.)
     
    Last edited: Jan 2, 2018
  2. Chris DeVoe

    Chris DeVoe Forum Resident

    I thought they said it was possible they could build a machine that could be both large enough and high enough resolution - but it would take five years to raise the funds and build it, and by then the whole film would have turned to soup. The other issue was residual heat of the x-rays would cook the part they were not scanning. The scanner there were using was a one-of-a-kind machine.

    They saved every cube, and due to the nature of film, they should be able to do a pretty decent job of reconstructing it - they know where every reconstructed frame is supposed to be in the film - just match the edges of one reconstructed frame to the cubes on either side of it.

    "I thought you said you could just read his brain electronically!" protested Ford
    "Oh yes, but we'd have to get it out first. It has to be prepared."
    "Treated" said Benji
    "Diced"

    Hitchhiker's Guide To The Galaxy
     
    Last edited: Jan 2, 2018
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  3. JohnO

    JohnO Forum Resident

    Location:
    Washington, DC
    Nope, I still don't understand. The machine they pictured looked like it could hold that whole pancake. The scanning rays can be focused and limited to any section they want. They could test on any other film, even a decent nondecomposed film, to check for temperature - then they could limit the scan area to an area that would not produce excessive heat in the scan of a small piece of the pancake.
     
  4. Chris DeVoe

    Chris DeVoe Forum Resident

    The machine in the photo was the laser engraving machine that was used to cut the cubes. It's a Universal Laser Systems model. I've worked on them.

    Edit to add: There were two machines in the 2nd part of the article, the laser cutter and the CT machine. I read the brochure from the maker Nikon, and the X-Ray source is fixed, and the sample is rotated on three axes, which limits the size of the sample. It sounds like they had a Nikon XT H225 heavily modified for their purposes.
     
    Last edited: Jan 2, 2018
  5. JohnO

    JohnO Forum Resident

    Location:
    Washington, DC
    The picture above that (Part Two page), the machine labeled "HMX 225" and "X-Tek Leading X-Ray Technology" is the pic I was referring to. It looks like it could hold the whole pancake. If they did not use that machine, they should not picture it. And they should picture the machine that they did use. The article refers to a custom "MuCAT 2". I want to see a picture of it, and if it is too small as "custom designed", they could re-custom design it, rebuild it, to hold the whole pancake.
     
  6. Chris DeVoe

    Chris DeVoe Forum Resident

    Right - it would just take years to raise the funds and build it.
     
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  7. longdist01

    longdist01 Forum Resident

    Location:
    Chicago, IL USA
    In order to get a reasonable image from the film, we needed a scanning resolution (voxel size) of 20 µm (millionths of a metre). Thus, a 30 mm diameter film reel is 1500 voxels across. A 300 mm diameter reel would be 15,000 voxels across. The Morecambe and Wise film exceeded this dimension in places, probably requiring around 20,000 voxels. Technologically, a detector with sufficient resolution could be created, but this is not the fundamental problem. The physical/mathematical laws dictate that if the size is increased by a factor of n, the number of X-ray photons required for a given image quality (signal-to-noise ratio) must increase by a factor of n4 (n×n×n×n). Thus, an increase in size by a factor of 10 (10×10×10×10) would require 10,000 times the number of photons. This could possibly be provided with a synchrotron X-ray source (a large machine about the size of a football field), but no detector exists that could cope with that massive exposure. An X-ray beam that intense would also generate enough heat to incinerate the film. Oil cooling might help, but the whole film would have to be dimensionally stable to around 1 part in 40,000. After these sorts of back-of-envelope calculations, I confronted Charles with the prospect that this could not be done. Even if (a very big “if”) we could conceive of building an entirely new type of imaging system at a synchrotron, it would take three to five years to get it funded and built; by which time the film would be soup. The only other option was to chop it into manageable pieces; a suggestion I did not think would be terribly palatable.

    Charles was faced with cutting the last remaining record of this episode into little bits, or else letting it decay into goop. Seemingly with no hesitation, he opted for the former option and plans were rapidly put into place for Queen Mary to work with the BBC to restore images from the film. Since mechanical cutting would disturb the “Marmite” it would have to be cut with a laser. I asked Charles if he could track down such a facility and he did; in our own engineering department.


     
  8. JohnO

    JohnO Forum Resident

    Location:
    Washington, DC
    I don't think so. So. Whatever this "MuCAT 2" is, does it have only a 1cm space? I hope not. Probably, I am guessing, it has a 10cm cubic space, and they focused it in on the 1cm cube of film. They would only need to take its guts out and rebuild it into a different shielded case that could hold the whole pancake.
     
  9. JohnO

    JohnO Forum Resident

    Location:
    Washington, DC
    That's just wrong, limited, thinking. As I said, scan 1cm x 1cm portions of the whole pancake each time, slightly overlapping. You do not have to scan the whole 30 cm (~12 inch) pancake in one go.
     
  10. Chris DeVoe

    Chris DeVoe Forum Resident

    Again, due to the nature of film, putting the frames back together, while hard, is the least difficult part of the project. Sort of how they cracked the genome - chop it up onto bits, then reassemble the bits afterwards.
     
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  11. longdist01

    longdist01 Forum Resident

    Location:
    Chicago, IL USA
    Maybe the article is wrong, or the information is faulty. Go ahead and ask them JohnO.

     
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  12. Chris DeVoe

    Chris DeVoe Forum Resident

    From the brochure of the machine that was modified:

    To generate a 3D CT volume, a series of sequential x-ray images are captured as the object is rotated through 360 degrees. These images are then reconstructed to generate a 3D volumetric representation of the object. In addition to the outer surfaces, the reconstructed volume contains all the information of interior surfaces and structure - as well as information on the material structure. It is possible navigate through the CT volume at any given point through any plane. As a result even interior measurements can be easily obtained, as well as the added benefit of localizing structural material imperfections on identifying assembly errors not usually visible through traditional methods of NDT.​


     
  13. Chris DeVoe

    Chris DeVoe Forum Resident

    I mentioned this to my wife, and she told me about a documentary she saw last year called Dawson City: Frozen Time about a cache of 500+ silent films that had literally been dumped into a former swimming pool as landfill. The frozen ground helped preserve the film and halted the deterioration of the film.

     
  14. beccabear67

    beccabear67 Musical Omnivore

    Location:
    Victoria, Canada
    It's amazing they can get something at all from what was thought a lump of next to nothing. I have the first set of BBC Morecambe & Wise shows but this was merely 'nice to see', while if they got frames from a missing Doctor Who or A For Andromeda I'd be very jazzed about that! But... if they can put a lot of frames and some sound together... B-toom! :cool:
     
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  15. balzac

    balzac Forum Resident

    I'm confused as to why such a project needs to be questioned. It's not like all other topics discussed and celebrated among audiophiles and videophiles are cost effective or profit-generating or saving lives.

    This project is clearly about more than snapping some pics of a few frames of a decaying film, and I would presume, as is the case with a myriad of studies and tests and experiments, the money put into it is done so with the idea that it's furthering knowledge and experience with this sort of stuff.

    It's especially presumptuous to start assuming it's a big giant waste of money if you A) Don't know what the project is costing and B) Don't know what the end result might be.
     
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  16. sunspot42

    sunspot42 Forum Resident

    Location:
    San Francisco
    Really impressive work, and I'm certain of use to film restorers all over the world.
     
  17. Chris DeVoe

    Chris DeVoe Forum Resident

    At some point, there will be super-high resolution X-Ray CT scanners, and they'll be able to scan an intact roll of decomposing film.
     
  18. goodiesguy

    goodiesguy Boulful Sallad

    Location:
    New Zealand
    I bet people said the same thing about Chroma-Dots on UK kinescopes too, and look how that turned out, we now have an episode of Dad's Army and the Are You Being Served? Pilot back in colour like they were originally recorded and broadcast.

    Plus, I don't think people realise how big Morecambe & Wise are still in the UK, they weren't just the co-stars on the Beatles Ed Sullivan shows. They still consistantly get repeats and given prime time slots every Xmas on the BBC.

    Having even a couple of frames recovered is still better than nothing at all.
     
  19. Chris DeVoe

    Chris DeVoe Forum Resident

    From what I read, they scanned every block of the film. It will be interesting if they are able to recover a lot more data, or entire scenes. It seems like a "big data" project.
     
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  20. kwadguy

    kwadguy Forum Resident

    Location:
    Cambridge, MA
    Wow, GREAT article. Amazing work. Thanks for posting.
     
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  21. sunspot42

    sunspot42 Forum Resident

    Location:
    San Francisco
    Do they have the audio already from some other source?
     
  22. Chris DeVoe

    Chris DeVoe Forum Resident

    No idea, but I suspect that there are fans out there who taped it on cassette or reel-to-reel.
     
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  23. sunspot42

    sunspot42 Forum Resident

    Location:
    San Francisco
    I'd assume the same...
     
  24. jtiner

    jtiner Forum Resident Thread Starter

    Location:
    Maine
    My take on the audio was that they could potentially recover it from the scanned optical track. It's visible in the sample frames. But as posters have said, there may be off air reel to reel audio somewhere. The off air fan recorded stuff made via direct connection to a television receiver (like some of the Who stuff) would be of substantially better quality than the optical track on the film recording.
     
  25. antoniod

    antoniod Forum Resident

    This film of Morecambe and Wise is in such bad shape you can't see the hair on Ernie's short fat hairy legs!
     
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