Autodesk 64006-051108-9001 User Guide - Page 76

68 Chapter 6: Pre-processing Sharpen is an edge-sharpening filter that uses an Unsharp Mask algorithm. The algorithm name comes from the physical way this effect used to be accomplished in the darkroom with film masks. Because it affects mostly edges, this filter does not enhance noise as much as a standard sharpen algorithm and is therefore less detrimental to encoding than a conventional sharpening filter. There are two controls to the Sharpen feature: •The Radius slider affects how far the sharpening effect extends from each pixel. Higher numbers usually give more pronounced results. •The Amount slider controls what percentage of the sharpened image is overlaid on top of the original image. The higher the setting, the stronger the effect. As with the other filters and adjustments, use the Dynamic Preview to get immediate feedback as you experiment with the settings. Adaptive Noise Reduction The Adaptive Noise Reduction filter often improves the encoding of video. This filter reduces the fine detail and noise of an image while leaving the edges of objects in the picture sharp, so that the resulting file encodes better but does not look blurry. Use this filter with most video sources to improve encoding. To optimize video and images, the Adaptive Noise Reduction filter identifies areas of fairly flat color or gradients and blurs only these areas to improve compression. For most video, the Mild preset is best. If you have low-quality video due to a poor source or a very inexpensive capture card, you may get better results with the Moderate or Extreme setting. To customize the Adaptive Noise Reduction filter, choose the Custom option and manually set the filter parameters using the Threshold and Amount sliders. •The Threshold slider controls which parts of the image get processed. Lower settings affect only flat areas of the image whereas higher settings affect the entire image. •The Amount slider controls the strength of the noise reduction by increasing the amount of blurring that is performed. Higher settings produce stronger noise reduction. However, very high settings may introduce unusual artifacts into the video. Temporal Processing The Temporal Processing option, which is available when you choose the Custom option, smooths pixels over time to remove even more video noise to further improve encoding quality in the Adaptive Noise Reduction filter. In addition to general video noise, this filter can eliminate one-frame-duration artifacts, such as lines resulting from dirty video heads or worn tape.