“The Restoration of The Thousand-Stitch Belt (1937): Utilizing analog and digital techniques to retrieve the colors of a two-color system”

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Mr. Masaki Daibo (Assistant Curator of Film at National Film Center, The National Museum of Modern Art, Tokyo [NFC]) and Tomohiro Hasegawa (Color Scientist at IMAGICA Corp.) spoke at the Joint Technical Symposium [JTS], held at the National Museum of Singapore on March 7th, 2016.

National Museum of Singapore

National Museum of Singapore

Scene from the presentation

Scene from the presentation

Images provided by: National Film Center at The National Museum of Modern Art, Tokyo

provided by: National Film Center at The National Museum of Modern Art, Tokyo

Images provided by: National Film Center at The National Museum of Modern Art, Tokyo

provided by: National Film Center at The National Museum of Modern Art, Tokyo


The presentation

The title of the presentation was “The Restoration of The Thousand-Stitch Belt (1937): Utilizing analog and digital techniques to retrieve the colors of a two-color system.”
The presentation lasted about 20 minutes at the gallery theatre in National Museum of Singapore. Mr. Daibo from NFC provided the background leading to the film’s restoration, to the overall workflow and their simulation at IMAGICA West to recreate this unique two-color system. Hasegawa from IMAGICA presented the second half with a original digital restoration method developed for this project.
The details of project can be found in the following link (details available only in Japanese, English summary):
http://www.momat.go.jp/ge/wp-content/uploads/sites/2/2015/01/20_pp.22-34.pdf
[Kazuki Miura and Masaki Daibo, “The Restoration of Senninbari : Reviving a Two-Color System through Analog and Digital Technologies.” Bulletin of the National Museum of Modern Art, Tokyo, volume 20. 2016: 22-34.]

The following describes the restoration process, with excerpts from the presentation.


Identifying color that cannot be expressed in a two-color system

The Feedback loop for conforming to "multicolor" color gamut

The Feedback loop for conforming to “multicolor” color gamut

Limiting colors that cannot be expressed by the two-color system was one of the key elements in digitally restoring The Thousand-Stitch Belt. IMAGICA West attempted to reproduce the process used at the time of creation, utilizing film stocks and agents available today. LUTs* were created based on chart measurements and analysis. The result was a LUT that will glow green or yellow, warning the viewers of colors that cannot be expressed in the two-color system.

*LUTs (Look Up Tables) are image modifying files used mainly for color adjustments


Effectively grading by applying the LUT

Pictures provided by: National Film Center at The National Museum of Modern Art, Tokyo Left: Pre-color grading Right: color grading results

provided by: National Film Center at The National Museum of Modern Art, Tokyo
Left: Pre-color grading Right: color grading results

A LUT is applied to the pre-color graded image on the left, warning viewers of colors outside the legal color space [based on the two-color system] caused by various elements in the process. To the right, is the result of the color grading (performed by colorists, staff whose specialty is in color and adjusting them appropriately) with the LUT applied to the original image. There is a noticeable decrease in the green warning area. Having these visual warnings in place naturally persuaded the color balance to match the original image. An effective color restoration was made possible by the colorists learning the balance of this particular format.


LUT creation

The usage of the photochemical simulation weighed largely in the creation of the LUT. After deliberation, the best result came from ruling that a certain color will be treated legal [within the two-color gamut* ] if the color difference between the simulated data and the graded color is under a certain predetermined value. The LUT was created under this rule. Legal colors were kept as they were and green or yellow glows were added to colors outside the color gamut.

The color grading during this restoration effectively manipulated the two-color system characteristics and its color space. As a result, we were able to retrieve the original colors of The Thousand-Stitch Belt. We hope this experience and method could be applied to other color systems in the future.

This restoration process has retrieved the colors of the two-color system, identifying its color gamut and utilizing its information in color grading. As a result, we were able to reproduce the original colors seen in The Thousand-Stitch Belt. With this knowledge, we will be able to apply this method in other restorations where color directions by the creators cannot be given, or projects where detailed color analysis are difficult to achieve. We hope this method will become useful in other restorations with unique color reproductions.

As reported here, IMAGICA continues to collect technological knowledge by restoring original colors, critical in film restoration.

* Range of colors. Different color gamuts exist based on devices and color standards.

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