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  3. More than 2 million films languish in vaults(地窖)around the world, some of th

More than 2 million films languish in vaults(地窖)around the world, some of th

游客2023-10-31  34
问题     More than 2 million films languish in vaults(地窖)around the world, some of them so badly damaged they can no longer be screened. If nothing is done, they could disappear for good, like half the films made in the US before 1950. But research at the university of La Rochelle in France and Monash University in Clayton, Victoria, promises an automated technique to restore these old films to their former glory.
    Films can be cleaned chemically or by using ultrasound. But this is time-consuming and expensive, and chemicals can also damage the original. Another approach is to digitize the film and then clean up the digital version frame by a frame— a daunting job. When Disney cleaned up Snow White for release on DVD, for instance, graphic artists worked in shifts on 40 computers day and night for 18 weeks.
    These computer-aided techniques remain very expensive, says Samin Boukier, who started work on an automated system in La Rochelle. Only an automated system can hope to salvage the archive(档案文件)of deteriorating films.
    Once a film has been scanned in, the first stage of the process is to correct flicker caused by the film slipping — the result of damage to its perforations. The system works out if two frames are usually close to each other or far apart, and corrects any anomalies.
    Dust spots usually occur only on single frames, so the system looks for small stains that are visible on one frame and absent on its neighbors. The software repairs the image by sampling the unspoiled area of the image on the adjacent frames and replacing the dust spot with an average of the sampled pixels(像素).
    Detecting scratches is more complicated because they may run over several frames and can be confused with vertical lines that are part of the film. But a telltale pattern often gives them away: Scratches are normally caused by the mechanical parts of a projector rubbing on the film, so they tend to repeat at regular intervals.
    The system looks for a periodic pattern of this type from frame to frame, predicting when it should occur in the subsequent frames. Having identified the scratch and its duration, the software then repairs the damage by taking pixels from undamaged frames before and after the scratch. This smoothing effect avoids any sharp edges in the restored image.
    "When detecting dust particles," says Boukir, "95 percent accuracy is acceptable. But with line scratches it has to be better. The removal of significant scene details would have disastrous consequential effects on the resulting restored movie," she explains. Because of this, some level of human intervention will be needed.
    Once restored, the digitized films can be viewed by future generations without risking more damage to the original by running it through a projector. " Film has a hundred-year history, but the knowledge of how to store it properly is only 15 years old," says Godfrey Pye of Sunset Digital, a Hollywood-based company that specializes in cleaning up old movies. [br] How does the automated system repair the damage caused by scratches?
选项 A、By reducing the sharp edges.
B、By removing pixels from the damaged frames.
C、By using pixels from other frames.
D、By predicting when it should occur and avoiding it.
答案 C
解析 事实细节题。根据文章倒数第三段中倒数第二句可得出A，B，D均不是答案。
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