Notes on the 2010 restoration
from Thomas Bakels
of Alpha-Omega Digital, Munich
By Glenn Erickson
Earlier in the year I had the privilege of attending a three-day seminar of the Association of Moving Image Archivists (AMIA), and was present for a presentation given by Thomas Bakels of the German digital film restoration company Alpha-Omega digital GmbH. I'd corresponded with Mr. Bakels years before, when he generously offered to answer questions about the 2001 restoration of Fritz Lang's Metropolis. From Bakels' hometown in Munich, Alpha-Omega performed the digital restoration for that large-scale reconstruction job, which combined film elements gathered from archives all over the world.
Thomas' lecture was so good that I was surprised when the media coverage to promote the various 2010 premieres and theatrical engagements of The Complete Metropolis by and large ignored the digital restoration aspect of the restoration, which was considerable. This includes two long-form documentaries on the restoration: the contribution of the archival experts at Friedrich-Wilhem-Murnau-Stiftung is covered, and so is the (fairly amazing) story of the way the lost negative was secured in Buenos Aires, as related by Francisco Martíin Peña and Paula Félix-Didier. Great achievements, and praise well deserved.
But the most we heard about the actual restoration is that the footage from Argentina looked terrible, and required restoration. That doesn't begin to describe what really had to be done to make the new scenes presentable -- in their raw state, the Munich archivists were concerned that they might be too damaged to go before the public in a new presentation of the full feature.
The Alpha-Omega digital Restoration Site has several fascinating pages on the restoration, with film clips of before & after examples, including shots of the interesting work performed to re-do German versions of shots with Spanish text. Alpha-Omega also links to the websites of other digital effects companies that performed specific restoration tasks, like Scientific Media in Berlin. The company TrickWILK, also in Berlin, specializes in calligraphic text for films... their work on letters and calling cards seen in the movie -- and this Bible page -- is quite beautiful.
Alpha-Omega digital's biggest contribution to the restoration appears to be in software design -- that mysterious "third pass" that cleaned up so much of the scratch damage to the Argentine footage. I asked Thomas if he could tell us more about this, and perhaps discuss his overall feelings about the 2010 restoration.
From Thomas Bakels, November 26, 2010:
The Complete Metropolis
I'd like to remark on two aspects of the work on Metropolis. My company once again won the bid to integrate the new Buenos Aires footage into the already existing 2001 restoration.
This is the first time on a feature film that I have seen material look so bad, that I thought it might be unrestorable. Every image on the 16mm negative is severely scratched, to the degree that no 'healthy' content exists to be useful for cloning pixel information between frames. Faced with this situation any attempt to use traditional digital retouching methods would without a doubt fail.
If a shot contains 300 frames, and 20 of them look better than the rest, a restoration artist will 'steal' information from the 20 good frames to "heal" the other 280. Because the repetition of information is an unavoidable result of this method, after a while the content begins to look static, frozen, like a projected still.
We needed to find an alternate method different from the traditional plan of borrowing and trading visual information between film frames. That led us to create an algorithm that would "heal" the damaged image without accessing information from adjacent frames at all. Our thoughts fixated on an analysis of what the human eye sees and what the brain 'filters out'. In our heads a doorknob is a doorknob: no matter how much damage is superimposed over it, we can still "read" the door-knob behind the rain of scratches.
This was the beginning of the journey to design a new restoration software tool. The Murnau Foundation put their trust in our ideas and our experience. It was extremely courageous of the Foundation to believe in our idea of a scratch-healing software, which did not yet exist and therefore could not be demonstrated at the time of decision. Their faith in our plan was very strong. This of course placed us in a rather tight spot of actually delivering the software to back up what was still only a theory.
After three weeks spent developing the algorithm, I sat in front of the computer late one afternoon to run the latest version, and saw it work! That moment's positive result -- call it "proof of concept" -- was truly magic. Defects disappeared in front of my eyes, completely automatically and without using neighboring image content at all. After seeing that first sample, I couldn't stop. I tested material all through the night until sunrise of the next day. It worked!
From that moment on we continued to refine the process of cleaning the images. Yet we still generated digital artifacts all over the frame whenever something in the image was moving. The software needed to be taught more 'knowledge about movement' within the frame, so we kept at the problem. Again, this required us to experiment in directions different those found in existing software. Those programs tended to track image content throughout the scene, but we thought it would be better to describe the movement as a technical property of the entire digital image. After a while we formulated just such a mathematical explanation, and the software began to understand the nature of movement in the frame.
Yet, we found that, as the "movement detection" became more detailed, more groups of scratches registered as movement and therefore came back into the image. We tweaked this balance of algorithms until we found a compromise in what seemed to be a battle that couldn't be completely won. The result is a far cleaner image than what we started with. The remaining scratches appear more transparent, allowing the viewer to better concentrate on the image behind them.
We at Alpha-Omega have given this new proprietary software the name "RettMagic".
On my non-technical response to the overall restoration of Metropolis:
Speaking for myself, I had a hard time understanding the plot of the first major restoration of Metropolis in 2001. The attempt to fill the missing story parts with text inter-titles didn't work well for me. I caught myself reading the descriptions but not imagining the missing story sections. With the Argentine segments restored -- some of them up to 7 minutes in length! -- looking at the film now is a big improvement to me. With the story now almost complete, the Machine-Man is now a side-act, and other characters in the story have become vital to the plot. It is like watching a completely new film.
The patchwork of the fine-quality segments from 2001 with the Argentine footage looked truly terrible before the new material was digitally restored. The Argentine fill-ins will of course always be obvious, whether one is or isn't aware of the techniques used to improve them. But the film's scenes now flow smoothly and the rough sequences succeed in carrying the viewer through the story. I think that is the major improvement over the 2001 version.
I thought it very satisfying that, when the archivists Anke Wilkening, Martin Koerber sat with us to watch the final restored version for the first time, we found ourselves admiring the scene connections. We followed the narrative, not once mentioning the added footage, which is of course still ugly when compared with the 2001 elements. We were amazed that all of us were "watching a movie'" instead of listing errors or being shocked by the contrast in quality scene to scene. That I believe is the true measure of the restoration. It is now easy to watch the movie, whether or not it happens to be your type of film. Before the digital restoration, expecting the viewer to enjoy it was simply too much to ask. -- Thomas Bakels.
Thomas Bakels' Alpha-Omega digital Restoration Site has several full-video before & after demonstrations of the digital cleansing required to make the Argentine footage viewable. Remember to access the pages "Image Restoration" and "Reconstruction".
Over the last eleven years, DVD Savant has posted many reviews and articles on Metropolis. Here are the others:
My first article (1999) comparing Metropolis to Star Wars, Sorting out the Pulp. It has some early grousing on my part as to the lack of anything like a complete version, and even gripes about the film's projection speed!
The next entry is A Theatrical Review of the 2001 Digital Restoration. This is from the first screening at the Los Angeles County Museum of Art on September 29, 2001, three weeks after 9/11.
My review of Kino's Restored 2001 Authorized Edition
Then, skip to 2008 for my excited post on Fritz Lang's Lost Metropolis -- Rediscovered!
Which is followed by my cranky return to the issue of projection speed, Metropolis and the Frame Rate Issue from May 1, 2010.
And my latest review of Kino's The Complete Metropolis, November 27, 2010.
My account of the TCMfest North American Premiere of the 2010 Restoration is in the Savant Archived Column for April 26, 2010. and my column coverage of
Thomas Bakels' appearance at the AMIA "The Reel Thing" convention is covered in the Savant Archived Column for August 17, 2010.
--- Glenn Erickson 11/26/2010
DVD Savant Text © Copyright 2010 Glenn Erickson
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Also, don't forget the
2010 Savant Wish List.
T'was Ever Thus.
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