The first black-and-white-to-color 4K restored feature film "The Eternal Electric Wave", jointly completed by the CCTV Central Video 5G New Media Platform and the China Film Archive, premiered at the Beijing International Film Festival on September 28 and will be released nationwide on October 6. Produced in 1958 by bayi Film Studio, the original film "The Eternal AirWave" is the first classic film in New China to tell the hero of the party's hidden front. In this black-and-white to color 4K restoration version, the project restoration team combined the human-computer interactive AI coloring with independent intellectual property rights in China with traditional restoration techniques to repair and color the original black and white images of the film frame by frame, injecting fresh vitality into this red classic.
"Eternal Waves" black and white to color 4K restored version poster.
"The Eternal Wave" is 116 minutes long and has 165,000 frames. Wang Zheng of the restoration team said that to achieve film standards, every frame must be carefully considered. While using AI to color, the restoration team examined the character costumes and environmental colors in the film, and the colors of the "Dream of the Red Mansions" cover, cheongsam, billboards and other props that appeared in the film were well documented, and even communicated with the Peace Hotel by telephone in order to verify the details. The restoration team lasted 7 months, with more than 100 participants before and after, and almost worked day and night to finally complete the first black-and-white to color 4K restoration feature film.
Ai coloring is not perfect, and it needs to be manually repaired
Hu Xiaobin of the restoration team introduced that the principle of AI coloring is to let the computer learn a lot of materials, and gradually form a very large-scale training set, and match the colors in the picture through the materials of the training set. Take "The Eternal Wave" as an example, this spy war film about the hero of the party's hidden front, the story takes place in Shanghai during the War of Resistance Against Japan, the restoration team will find the same shooting era, the same story era, the same genre, the same director of the film and television works as training materials for the AI, so that it can learn through this information and find the corresponding picture color suitable for "The Eternal Wave". If it is completely handed over to AI to color, the restorer Sun Fan said that it can be scanned in a day or two, but the problem is that the color on the AI will have a certain deviation, at this time it is necessary to repeatedly deliberate, increase the relevant materials in the training set, combine traditional manual repair methods, adjust to the appropriate color. "AI can learn, but you have to give it material and teach it how to recognize." Sun Fan said.
Black-and-white original and color restored stills of "The Eternal Wave". Picture courtesy of the tablet.
In the film, Miss Bai wears a cheongsam and does not know what color. Hu Xiaobin said that at that time, the team tried many colors, input silver, blue, pink, green, etc. into the AI model to experiment, found that only two colors were relatively stable, and finally chose one color.
The AI black-and-white to color technology independently developed by the China Film Archive has been very stable in color, but there will still be some small problems, which cannot meet the standards of film screening and need to be manually repaired. In particular, AI's ability to capture dynamic pictures will be weaker, "If the picture is relatively static, the picture scanned by AI will be very beautiful, and the artificial work will be less, if the scene in the picture is relatively large, the characters are still moving, AI may not recognize well, and the proportion of manual repair will increase." Sun Fan said that at this time, AI will also be "montaged", and it is still in the stage of trying to explore.
In order to verify the details, communicate with the Peace Hotel by phone
For the color of the clothes worn by the characters in the film and the color of the props in the surrounding environment, as long as it is well documented, the restoration team will examine it.
In the film, the character played by Sun Daolin took a copy of "Dream of the Red Chamber", which is an important prop for transmitting information. Restorer Wang Zheng said that in order to figure out what color the cover of the book was, the team also found red experts to study it. Because the story takes place in 1938, there was a lead print of "Dream of the Red Chamber", which may be light yellow, but according to the version of "Dream of the Red Chamber", dark blue is mostly. Finally, in order not to contrast with the yellow clothes of the characters in the film, the cover of "Dream of the Red Chamber" was selected to be filled with dark blue.
In order to figure out the environmental color of the Peace Hotel in the film, Wang Zheng and the Peace Hotel communicate the details by phone. The Peace Hotel has a peace museum, but it did not find what it needed, and the team had to borrow from the footage taken in the early film and television drama at the Peace Hotel and make corresponding adjustments.
Wang Zheng said that the restoration team analyzed the colors in the picture shot by shot. There is a real scene of the Bund in the film, a billboard on the side of the road, the team initially thought it was a colorful color, but from the Internet to find some photos of Xiafei Road in that era, found that those billboards are not flowery, only red or white. In addition, for the color of the qipao in the film, the team also found a teacher from the Beijing Institute of Fashion to examine it, and tried to be well documented.
Some colors can be verified, but some are really not. Sun Fan said that only according to the relationship between light and shade in the picture, it can be roughly inferred whether it is a dark color system or a light color system. "In fact, it is a process of artistic creation", Sun Fan will also judge the color according to the identity background of the character, "If it is a working person, it is impossible to wear big red and green, it does not meet the identity, some social flowers, the clothes are very fashionable, and it is not right for you to get her a gray-headed face." Sun Fan and the team also tried to use the black and white mode of the mobile phone to take pictures of different colors, comparing with the color of the picture, which feels closest to which to use.
Scrutinize every frame, even the flies
The general black-and-white film repair process is to convert the film into a digital file, and on this basis, some dirty spots, scratches and other problems are repaired to produce a clean black-and-white film. The restoration of "Eternal Waves" has an additional process, and it is also necessary to convert black and white to color.
"The Eternal Wave" is 116 minutes long and has 165,000 frames. Wang Zheng said that to achieve film standards, every frame must be carefully considered.
"The Eternal Wave" black and white to color 4K repair, the final is to be presented on the big screen, the monitor or monitor screen is still small after all, want to test the final repair effect, only on the big screen can be seen. When the restoration work is nearing the end, the Beijing International Film Festival has also begun, and the large screening hall of the China Film Archive does not have time to provide a review venue for the restoration version of "The Eternal Electric Wave" during the day, and can only wait for the early morning, "Start watching at 12:30, watch more than 2 o'clock, write down the problems that appear, and continue to change the next day." Sun Fan said.
"Every time you look at it, there are problems, it's all a matter of details," Sun Fan said, sometimes it is a hand that passes by, or something on the table moves, and there is even a character with a fly on his leg. The fly was there when the director first filmed it, but according to the environment at the time, it should not appear, and it was necessary to find a way to remove it during the restoration process. Sun Fan said that last year's restoration of "Blessing" also had a similar situation, there was a shot that was filmed falsely, and when repairing, it was necessary to find a way to change it. "If the director had a way to change this picture, he would have done it, but the technology couldn't have been achieved at the time." Sun Fan did not want to work hard for such a long time, but in the end he made the audience feel bad because of a little detail, "You want to give the audience the best viewing experience."
Teng Chao, a senior reporter of the Beijing News
Senior Editor Huang Jialing Proofreader Zhai Yongjun