Apply an NL Filter to Images in GIMP
Edited by Freya, VisiHow, Eng
You're watching VisiHow. In this tutorial, we're going to show you how to apply "NL filter" to an image in GIMP in Windows 7. "NL Filter" is a nonlinear filter, which means it combines the "Smoothing", "Despeckle", and "Sharpening" elements.
First, click "Filters" on the top-left of the window.
Move the cursor to "Enhance".
Then, click on "NL Filter...". A dialogue box will appear with a preview of your image.
You can click and drag your preview around or use the arrows and scrollers to select an area.
If the preview does not appear, ensure that you have the "Preview" box checked.
Now, click one of the options in "Filter". You can click "Alpha trimmed mean", "Optimal estimation", and "Edge enhancements". For this tutorial, let's click "Alpha Trimmed Mean". This option will not work if you have the alpha channel in your image. This affects the whole layer, not a selection.
Next, you can adjust the "Alpha" and "Radius" values. You can do that by clicking or clicking and dragging the scrollers or by typing the values to the right.
When you are satisfied, click "OK" to apply your changes to the layer.
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Video: Apply an NL Filter to Images in GIMP
Recent edits by: VisiHow, Freya