User Guide

User Guide Neat Image
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12
20-Nov-03
compression artifacts can stay in the output image.
As a rule, if the device noise profile has been built properly, it is not necessary to increase the noise
levels by more than 50%. If the input image contains strong surges of noise in the high frequency
range, it is recommended to increase the high frequency noise level up to +20 to 40%.
If the input image contains strong low frequency noise then you may need (in addition to low
frequency component filtration
settings) to switch on the very low
frequency filter (check the Very low
freq checkbox in the Noise Filter
Settings box).
If the input image contains strong color noise, it is
recommended to increase the Cr and Cb noise levels
to +30%. In some cases, it may be useful to increase
these noise levels up to +100%.
• Adjust noise reduction amounts (optional)
⇒ Use the High, Mid, and Low; Y, Cr, Cb (R, G, B) noise reduction amount sliders.
You can vary the noise reduction amount for each frequency and channel component of the input
image. The higher a specific noise reduction amount, the more of the detected noise is removed in
the corresponding image component. Be careful, setting the noise reduction amounts too high can
lead to loss of fine details and unnaturally looking (over-smooth, plastic-like, see page 44) results.
Too low amounts may be not enough to sufficiently remove the objectionable part of the noise. You
need to balance the noise reduction amounts (most
importantly, the amount of noise reduction in the Y
channel) to get the result that looks best to your eyes.
If the input image has only fine (high frequency) noise
elements you can utilize only the high frequency filter and
switch off the filters for other frequencies by setting their
amounts to 0%.
Turn on the Smooth edges checkbox to make edges and
lines in the image look smoother (see an example on the
right).
• Use preview
⇒ Use the preview when adjusting the noise filter settings.
After you have made changes to the noise filter parameters, do not forget to check the preview.
1
Use the preview on different parts of the image to get a better feeling for the results of noise
reduction.
If the noise filtration looks too strong (weak) try to decrease (increase) the noise levels and/or noise
reduction amounts for the appropriate channels and/or frequency ranges. If this does not help,
probably the device noise profile is not accurate enough. Return to Step II, page 9, and additionally
fine-tune the device noise profile (analyze a featureless image area with the manual fine-tuning
noise analyzer.
• Use Component Viewer (optional)
The Component Viewer is intended for detailed examination of both frequency and channel
components of the image. Find more details about using this tool in the Component Viewer subsection,
page 28.
• Use Variant Selector (optional)
The Variant Selector is designed to compare several variants of filtration side-by-side to find the
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Using auto recalculation of preview is recommended (see Filtration options, page 38).
Noise samples of different frequency/size are
shown in the Noise filter settings box. These
are examples of grainy structures typically
regarded as noise.
Smooth edges
Off On
As human vision is not very sensitive to
variations of colors, strong filtration in the Cr
and Cb channels does not noticeably distort a
n
ima
g
e, but efficientl
y
removes color noise.