Ensemble Designs 8500 Composite / SD Legalizer and Video Processing Frame Sync - Manual (Page 21)

8520 Digital Noise Reducer Configuration
The 8520 DNR is motion and scene adaptive. It removes unwanted noise and artifacts,
making it perfect for MPEG compression preprocessing and satellite or ENG feeds.
Several forms of noise reduction are employed to ensure the best possible performance.
Recursive Temporal Noise filtering includes Simple Recursive, Motion Adaptive and
Motion Adaptive with Impulse filter. Controls are provided for maximum signal to noise
improvement and for noise threshold. These can be set manually or run in automatic
mode.
Motion Adaptive Recursive Noise filtering works on a pixel by pixel basis, comparing the
current frame to frames that have already been filtered. If the change that is detected is
small, it is considered noise, while if it is large, it is considered motion or a scene change.
The detection process uses an LMMSE (Linear Minimum Mean Square Error) filtering
algorithm to evaluate the presence of motion. Combining this algorithm with recursive
temporal filters preserves fine detail while reducing noise in the presence of motion,
including rapidly moving objects and scene changes. Motion trails are minimized while
avoiding hard motion failures that some adaptive noise filters can exhibit.
The DNR menu gives six choices of operating mode:
1. Automatic Lo: A good setting for most material. Noise is reduced and the NR
Factor and Threshold displays will be seen to change dynamically with video
content. A moderate amount of noise is removed with few motion artifacts
produced.
2. Automatic Hi: NR Factor and Threshold receive enhanced values for greater
noise reduction with somewhat increased chance for motion artifacts to appear.
3. Adaptive: This manual setting allows the operator full control of all settings. A
better mix of noise reduction vs motion artifacts is possible but, being a manual
mode, it may not be possible for the operator to react optimally to changing scenes.
4. Adaptive/Impulse 1: Same as Adaptive with the addition of an impulse filter for
removal of large, narrow amplitude noise pulses.
5. Adaptive/Impulse 2: Same as Adaptive with the addition of an impulse filter for
removal of a wider bandwidth of noise. More softening of detail will be seen.
6. Non Adaptive: For still pictures, can be set for optimal noise reduction.
A special Luma Tie mode reduces dot crawl artifacts from composite originated material
by identifying cross-color and cross-luminance effects as unwanted noise.
The Show Noise output mode displays what areas of the picture are being affected by the
noise reducer. Noise is represented by white or black, while unaffected areas are repre-
sented in gray. This handy mode makes it easy to set optimum adjustments for the
material being processed. The Split Screen mode lets you compare the processed output to
the original signal.
8500-21
Model 8500 Series Modules