TVB Europe 78 November / December 2020

Page 16

FEATURE

Carry On... Up the Kyber before and after being remastered by ITV Content Delivery

can manually remove any that it misses, so in theory we can remove all of the dust and have a spotless film. The problem is that the more aggressively the software looks for things to remove, the more likely it is to result in false positives, removing items that are supposed to be part of the scene. For example, in the battle scenes in the final act of Carry On... Up the Khyber, we came across three elements that the software was repeatedly picking out as a defect to be corrected: flashes of gunfire, rubble from explosions, and the thin swords of the Burpa tribe, all of which were being removed to varying extents. This isn’t a flaw of the software; it’s actually working as intended. If you imagine the moment a gun is fired as captured on film, you have the frames immediately before the gun is fired, a single frame in which a bright white flash is visible at the end of the gun, and then the frames after the gun is fired. In other words, you have one frame containing a white blotch that isn’t visible on the frames before and after, which is exactly what the software is looking for. As operators, we can combat this by turning down the aggressiveness and tweaking other settings, but even when the tool is working at its minimum, false positives are possible, especially with elements like gunfire.

16 | TVBEUROPE NOVEMBER/DECEMBER 2020

The solution was that for some shots, and even just occasional frames, we had to turn the tool off altogether, allowing the dust to remain. The difficulty comes in pushing the software far enough that it removes as many blemishes as possible, without removing anything else. That isn’t a hard-defined line; it requires some judgement, and a lot of trial and error. It’s a similar story with scratch removal, which works in much the same way as dust removal, in that the software looks for established parameters (in this case, vertical lines of user-set width and colours) and uses frames before and after to replace the pixels. And as with dust removal, there is the danger of false positives, in which the software picks out elements of the scene that it identifies as a scratch and tries to remove it. But even when it correctly picks out scratches, we have to be careful that its attempt to cover them up isn’t resulting in digital artifacting. A good example would be a wide shot, in which the scratch runs directly down a character’s face. In this situation, there may not be enough detail in the image for the software to adequately replicate the details of the face, and the result is slightly blurry, slightly pixelated. In this case, we would rather leave the scratch in, at least for the frames during which it runs over the face, as my preference as a viewer would be to see a film imperfection rather than a digital one. Of course, it’s possible to go through frame-by-frame, manually removing dust and scratches without relying on the automated software. In fact, this is a necessary part of our process. In cases like the aforementioned battle sequence at the end of Khyber, we had to comb through individual shots and scenes to manually remove defects. Where possible, we choose not to do this for entire projects because it’s hugely more time-consuming, and often less accurate – you’re relying on human eyes to pick out every defect in what can be a complex image, and inevitably things will get missed. The trade-off is that a human won’t mistake the flash of a gunshot as a piece of white dust, but we therefore find it more appropriate to trust the software, know its limitations, and correct any errors it makes along the way. In an ideal world, we would be able to remove every defect, to create a pristine reproduction of a print from 1968. The reality is that we can get 95 per cent of the way there, producing a result that is hugely cleaned up from the original scan, and a vast improvement over its standard definition counterpart. The last five per cent is a black hole. It consumes time and money in the relentless pursuit of perfection. Ultimately, it’s better to leave in a scratch that in the future could, with improved software and experience, be removed flawlessly, than introduce an artifact that will remain. Perhaps the appropriate question is not “where do we start?”, but “where do we stop?” n


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