User Guide

User Guide Neat Image
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18
20-Nov-03
About device name and device mode
It is recommended to specify these details to keep record of devices, device modes, and
corresponding device noise profiles that you use. This is important because the noise
characteristics of any two devices can be extremely different. Even a single device in different
modes can produce significantly different noise. Therefore, it is always better to use separate
noise profiles for different devices and device modes to avoid inaccurate filtration and artifacts.
Commenting on the device name and device mode parameters helps you to keep track of them
afterwards when you manually match the profiles and input images.
Automatic profile matching is using the EXIF data of the image files, not the Device name and
Device mode fields, so filling out these fields may not be necessary for auto-matching. However,
filling these out is highly advisable both for the clarity purposes and for the cases of EXIF-less
input images (in case of EXIF-less images, you will have to manually select a matching profile
based on the Device name and Device mode fields).
About cross-use of noise profiles
Naturally, it is always better to build a new device noise profile for each image, because such
profile better matches the noise of particular image. Nevertheless, a device noise profile can be
used to process many images received from the same device working in the same (or similar)
mode. Several device parameters should be taken into account when such a cross-use of profiles
is to be used.
It is most likely that any two images would be shot in different or slightly different conditions
(device mode, shooting conditions); therefore, the noise characteristics would be different. In the
table below, device mode data (for digital cameras) are described that affect the noise
characteristics the most (from the most to the less important ones):
ISO rate
50, 100, 200, 400, etc.;
depends on a camera
Higher ISO rate produces more noise.
Sharpness
adjustment
Low, Normal, High, etc.;
depends on a camera
Internal sharpness adjustment of a camera
makes noise more intensive. Using no
internal sharpness adjustment produces
least noise.
Compression
1:1 (or Uncompressed),
1:5 (or Fine), 1:10 (or
Normal), 1:20 (or Basic), etc.
or
2 bits/pixel, 4 bits/pixel, etc.
depends on a camera
Strong JPEG compression typically
produces more JPEG artifacts and destroys
image elements including noise; weaker
compression preserves more image
elements including noise created by the
image sensor. It is preferable to use the
lowest amount of compression possible for
the best results.
Resolution
1:1 (original resolution, like
1600x1200), 1:2 (downsized
in camera, e.g., 800x600), 2:1
(digital zoom, 2x), etc.
Camera’s internal interpolation (both
downsizing and upsizing, e.g., that of
digital zoom) changes many characteristics
of noise.
White
balance
Sun, Cloudy, Incandescent,
Fluorescent, etc.;
depends on a camera
White balancing changes characteristics of
noise (mainly of color noise) slightly.
If two images were shot in the same or similar conditions (most the above device mode data are
the same) then the noise of these two images should be very similar. If you have built a device
noise profile using one of these images, you can use this profile to filter both with good results.
If however, the shooting conditions were different then the noise components of two images
could be significantly different. In this case, cross-use of the device noise profile is not
recommended. Instead, build a new profile for another device mode.