User Guide

User Guide Neat Image
Copyright © 1999-2003 by ABSoft. All rights reserved.
11 20-Nov-03
4.3.1. Use preview to adjust filter settings
To use preview
⇒ Select any image area: press the left button, drag the mouse and then release the button.
When an area is selected, Neat Image will
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automatically apply filtration to the selected image area.
You can also manually invoke preview recalculation with
(the Preview button),
the Filter | Preview menu item, or the F5 hotkey.
As soon as the preview is ready, you can left-click on the selected area to temporarily switch back to
the original for comparison.
4.3.2. Adjust noise filter settings
The noise filter has separate settings for all frequency and channel components. There are the noise level
and noise reduction amount controls for all image components.
The noise level controls determine which image elements are
considered noise. Because the noise level controls are relative
to the device noise profile, their defaults usually produce
satisfactory results. The noise level defaults are 0%
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, which
means the noise levels are completely determined by the noise
profile. When the level controls are set differently, the noise
level estimations are raised or lowered accordingly. A noise
level can be in the range from –100% (which means no image
elements are considered noise, and therefore, noise reduction
will not be applied at all to the corresponding image
component) to +150% (which means noise reduction will be
applied to the image elements that are ‘weaker’ than 2.5 times
the noise level determined by the noise profile).
Noise reduction amount controls determine how much
reduction is applied to the image elements identified as noise.
Noise reduction amounts can be in the range from 0% (none
of the detected noise is removed) to 100% (all the detected
noise is removed). By default, the noise filter removes 100%
of detected noise
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. Decreasing the amounts can have a
positive effect if the input image contains some natural noise.
For example, when you are filtering images of asphalt, sand,
or anything else that contains fine natural noise-like features, it may be helpful to reduce amounts down
to 40-70%.
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Our experience shows that these values generally provide a good balance between
preserving image details and noise removal.
To adjust noise filter settings
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• Adjust noise levels (optional)
⇒ Use the High, Mid, and Low; Y, Cr, Cb (R, G, B) noise level sliders.
The noise filter has access to three frequency components and three channel components of the
input image. Corresponding sliders adjust the estimated noise levels for each of these components.
The higher a specific noise level, the more image elements in the corresponding image component
are considered noise. Be careful, setting a noise level too high can lead to removal of important
image details. Setting a noise level too low can lead to incomplete filtration: residual noise and
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If auto recalculate preview is checked; see Filtration options, page 38.
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Some of the noise level defaults may be different from 0%.
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Some of the noise reduction amount defaults may be different from 100%.
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See also Partial filtration, page 46, for additional tips.
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It is advised to switch off the sharpening in all channels when adjusting noise filter.