User Guide

User Guide Neat Image
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45 20-Nov-03
incorrectly chosen or poorly built profile can both produce plastic-looking results and leave residual
artifacts (see the previous question).
Q What is frequency?
A The term frequency is used in Neat Image to denote image elements (both important details and noise)
of specific size.
High frequency corresponds to image elements of smallest size. Medium (mid) frequency corresponds
to elements of medium size. Low frequency corresponds to image elements of (relatively) large size.
For reference, see the noise samples of different frequencies in the Noise Filter Settings
tab of the Filtration Job Editor.
Q The filtration process is slow, is this normal?
A This is normal, because the filtration algorithm is quite complex. We are working on further
optimization to provide better performance.
Q Is the input image automatically changed according to the profile that is being opened?
A The input image is NEVER changed. Neat Image always creates a new output image, which contains
the filtration results. The output image can then be saved to any file.
Q How to filter only the color noise (not the brightness noise)?
A When a YCrCb space is used, set the value of the Y channel noise reduction amount (in the Noise
Filter Settings box) to 0%. This will switch off filtration in the brightness (luminance) channel Y.
Q What is YCrCb?
A YCrCb is the name of a family of color spaces widely used in digital imaging, television, image
compression (e.g., the JPEG compression transform RGB images into this space), etc.
In 'YCrCb', 'Y' corresponds to the luminance channel, 'Cr' - to the Cr chrominance channel covering the
red to blue-green range, 'Cb' - to the Cb chrominance channel covering the blue to yellow range.
Because this space enables easy separation of the luminance and chrominance information, it suits the
needs of noise filtration.
Q Is processing via Neat Image best done before or after any other processing (i.e. tonal/color
correction)?
A Such operations as tonal/color correction are quite conservative from the standpoint of noise, i.e., they
do not significantly change the noise characteristics of the image. Therefore, filtering before or after
makes little difference – as long as the device noise profile is built and applied at the same stage of
image processing. For example, don’t use a device noise profile built with an unprocessed image to
filter a processed image.
Some digital cameras apply some color correction internally. Other cameras allow access to
unprocessed RAW data. Neat Image is a generic filter, which can be applied in both cases. The only
requirement is to use matching profiles.
On the other hand, image sharpening applied to a noisy image makes it much more noisy. It is best to
apply Neat Image filtration before sharpening (including internal camera sharpening). However, the
sharpening and noise filters of Neat Image can be used together because the sharpening is applied
AFTER noise filtration.