Neat Image user guide / Filtration process details
Stage II. Prepare a device noise profile
Use the Device Noise Profile tab in the Filtration Job Editor:
To filter the input image, Neat Image needs to know the characteristics of noise produced by the image acquisition device (digital camera, scanner, etc.) that the image comes from. The noise characteristics of a device working in a certain mode are stored in a device noise profile.
There are several ways to get a device noise profile that suits the input image:
- To build a new profile using the Auto Profile function with the
input image itself or with a specially prepared test image;
- To automatically select the most suitable device noise profile from a pre-built set of profiles
using the automatic Profile Matcher;
- To manually select a suitable profile from a pre-built set of profiles using their descriptions or file names.
The first option is often the easiest one provided the input image includes uniform featureless image areas that contain noise but no visible or important details. Neat Image can automatically find such image areas and analyze noise in there to build a noise profile of the image. When the image contains featureless areas, this way of preparing a noise profile is the most accurate and therefore recommended.
The last two options are available once you have a pre-built reusable set of profiles. You can
find some free profile sets for different cameras and scanners in:
- Profiles section of Neat Image web page;
- Device noise profiles section of Neat Image community forum;
- Other digital imaging forums and web pages from users of Neat Image.
If you cannot find a pre-built set of profiles, then you can easily build reusable profiles
yourself. Moreover, please be aware that using profiles built by other people may produce
less than optimal results with your images because of possible slight differences in noise properties
of cameras (scanners) as well as due to different imaging processing workflows used. Therefore,
we advise to use noise profiles built by others only as a starting point to learn how
to use Neat Image. To achieve better results consider building your own reusable profiles.
You can build a set of profiles for different device modes or just one profile to process one image. See the Device noise profiles section for detailed instructions on profiling.
Once you have a set of profiles for different modes of your imaging device, you can (automatically
or manually) select a profile that matches the input image. Or if you have just built a singe profile
specifically for the input image, then you can directly use the profile to process the image in
the Stages III-V.
To build a new profile using the input image
- Click (the Auto Profile with Regular Image button) on the toolbar, or select the Profile | Auto Profile with Regular Image menu item, or press F2.
Neat Image will find and highlight the image area selected for analysis (see the blue selection
box in the image viewer;
the blue color indicates that the area has been chosen by Neat Image automatically). Neat Image will
then automatically analyze the noise in that area and whole image.
In difficult cases, Neat Image may have trouble finding a uniform featureless area in the input image. You will notice that the selected area, for example, will contain some important image details. In such cases, Neat Image also warns you that the area is not suitable for analysis. It may say that the selected image area is not uniform in one or more channels, or is too small, or contains clipping in one or more channels. In such a case, move the selection (or draw a new one) to an area that does not contain any image details and if Neat Image does not show a warning anymore then click the same Auto Profile with Regular Image button again.
After the profile is built, check the Profile quality indicator in the
bottom of the Filtration Job Editor window. A profile built using a
uniform and featureless image area will show a high value in this indicator. If the profile quality
is high (for example, higher than 75%) then you can be sure that the noise profile is accurate.
In this case, you can consider the noise profile ready and proceed to Stage
III. Adjust filter settings.
If the quality is not high, try to select another uniform image area and use Auto Profile with Regular Image once again. That may not help still, especially if the input image contains only a few featureless areas. In this case, consider building a noise profile using a special test image prepared with the Calibration Target as explained in the Device noise profiles section.
To automatically select matching noise profile from a pre-built profile set
- Click the dropdown button in the tool bar and then select (the Profile matcher button) or select the Profile | Open Best Matching Profile menu item.
The Profile Matcher uses the EXIF data fields of the input image
to automatically select and open the device noise profile that best matches the device mode of
the image. The most matching profile is selected from the set of profiles stored in a special
folder (including its subfolders) specified in the application options.
See Profile matching options for more details about the following profile matching options: Profile Matching and Matching parameters priorities.
To manually select a noise profile from a pre-built profile set
- Click (the Open device noise profile… button, blue disk) in the Device Noise Profile box or select the Profile | Open… menu item. In the Open device noise profile dialog box, select the device noise profile to be opened.
- Select a profile using the popup menu: click on the button on the right side of the profile name shown in the top part of the Device Noise Profile box, and select a profile from the popup menu (if there is no popup menu, check the Folder options).
When selecting a profile that matches the device mode of the input image, use the profile file names and folder structure to guide your search. See Preparing profile set for different device modes: Stage III. Structuring profile set for more information on structuring profile sets.
To additionally fine-tune the loaded pre-built profile
You may want to additionally fine-tune the profile you have just loaded either automatically (using profile matching) or manually. You can fine-tune this profile to the current input image using (the Auto Fine-Tune button) or the Profile | Auto Fine-Tune menu item
. This usually makes the profile more accurate and better matching the input image.Please note that you do not need to fine-tune a profile if you have just built it using Auto Profile. Auto Profile automatically
applies auto fine-tuning so you do not need to repeat it.
Stage I :: Stage II :: Stage III :: Stage IV :: Stage V