Automated hardware-based restoration systems bring numerous benefits to broadcasters that need a means of upconverting their assets to 1080p

Reducing Grain and Noise

A certain amount of grain gives film its distinctive look and thus is often a desirable element in a finished master. Very visually similar to grain, the noise introduced by the camera is less desirable. Both grain and noise, however, present a challenge when media is being upconverted to 1080p. The degree to which video is grainy or noisy often depends on lighting conditions. Because the upconversion process increases the visual impact of grain and noise, varying levels of grain and noise across different scenes not only compromise the picture, but also can be distracting for viewers.

To manage and reduce noise and grain without eliminating all of the content’s filmlike character, sophisticated video processing systems use a combination of temporal recursive filters and spatial filters. Together these filters achieve consistently high quality, regardless of the amount of motion – or lack thereof – within each frame. In this area of the workflow, the balance may be tweaked manually to attain the same visual effect created in the original work.

Often, noise and grain reduction can also lead to a subjective effect which makes the picture appear to be softer, even though there has been no bandwidth reduction. Successful grain and noise reduction produces a sharper picture, with no loss of detail. Most restoration tools support horizontal and vertical edge enhancement to give the picture the appearance of harder edges that the human eye prefers. Once again, this subjective aspect of picture quality can be tweaked manually for best effect.

Stabilizing Frame Position and Luminance

The movement of the camera during shooting or later migration of frame position as a result of telecine weave can be distracting for viewers, and automated processing in post often is the most efficient and cost-effective means of solving these problems. Hardware restoration tools can tackle instability in real time by continually monitoring and analyzing the motion profile of a frame sequence. The system uses this data to identify a global motion vector for each frame and, in turn, to adjust and correct the position of the picture, frame by frame.

Sudden variance in luminance, or flicker, also is distracting to viewers, and automated restoration systems help broadcasters to resolve this issue quickly, as well. Once again taking averages over the full scene, the system can lessen the distressing impact of luminance changes.

Reaping the Rewards of Restoration

Automated hardware-based restoration systems bring numerous benefits to broadcasters that need a means of upconverting their assets to 1080p. These systems quickly resolve visual defects and help to

© 1973 Thames Television Ltd. Courtesy of FremantleMedia Enterprises” 35 © 1973 Thames Television Ltd. Courtesy of FremantleMedia Enterprises”

optimize upconversion, in turn maximizing picture quality in the final result. In addition to reducing the investment of time required, they decrease staffing requirements and provide versatile manual controls to enable easy user intervention when the human eye and more subjective judgements are preferred.

With their robust treatment of common flaws, today’s real-time systems enable fast, economical processing of content and allow broadcasters to upconvert and get the most out of their existing asset libraries as they undertake the transition to full 3G production and delivery.

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