Ensemble Designs 5470 Digital Processing Amplifier and Legalizer - Manual (Page 11)

Model 5470 Digital Proc Amp and Model 5475 DNR
• Chr Lo Clip – set the low chroma clip level to between – 40 and 0 IRE
(– 20 typical).
• Chr Hi Clip – set the high chroma clip level to between 100 and 140 IRE
(+ 120 typical).
The DNR menu is active when the 5475 DNR (Digital Noise Reduction) submodule option
is installed on the 5470 module.
The 5475 submodule removes unwanted noise and artifacts. It is motion and scene
adaptive. 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 detected is small, it
is considered noise, if detected as large, it is considered motion or 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.
User controls for the Motion Adaptive Recursive filter include a Noise Threshold, based on
how much noise is present in the incoming signal, and Maximum Signal to Noise improve-
ment, based on how much noise removal is desired. The threshold setting can be
automatic or user adjustable.
When set to Automatic, the noise level of the input signal is measured and the threshold
is set accordingly. This simplifies the setup of the noise reducer and makes it responsive
to varying input signal to noise levels. The need for operator intervention is minimized to
accommodate feeds of differing quality. Two types of automatic noise reduction are offered,
Automatic Lo or Automatic Hi.
When the combined Motion Adaptive Recursive and Impulse Noise filter is selected,
temporal impulse noise filter removes high level, narrow noise impulses—without
reducing fine stationary detail.
The output mode of the DNR can be set with the selections under the Bypass pulldown.
This selection is used in conjunction with the module bypass setting in the Output menu.
The Show Noise output mode displays which 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.
In addition to the 5475 motion adaptive temporal filters, horizontal bandwidth filtering
and luma-chroma delay filters are provided in the Filters menu. The luma delay path can
be adjusted relative to the chroma path delay (Y/C Delay function in the Trims menu) in
approximately 2 ns subpixel steps, providing the ability to correct luma-chroma delay
errors in serial digital signals.
5470/5475-11