Sharpening is a part of nearly every image processing. Selective sharpening allows to sharpen the important structures without to “enhance” the noise in the image. Already in Episode 6 I have shown a way to do this. And here is another way, High Pass Sharpening. It is often used in Photoshop tutorials and has no standard entry in the GIMP menus.
One step involves blurring – and this leads to a lot of different possibilities to change the effect. I explore asymmetric sharpening by blurring only into one direction.
Of course there are plugins available at the GIMP plugin registry.
A description of several sharpening methods is in our Wiki, I’ll add the high pass method today.
I got the recipe for this from a (very good) German book by Jürgen Wolf.
01:48 Good German book: Jürgen Wolf, GIMP 2.6
02:00 GIMP 2.8 release late in 2011!
02:20 Preparing the image
04:10 Contrast, black point and white point adjustment with the curves tool
05:30 The recipe for Highpass Sharpening
05:40 Duplicate the layer twice
05:50 Invert the colours
06:00 Set layer mode to Grain Merge
07:00 Merge the top layer down and set the layer mode to Overlay
07:50 Adjusting the effect with the opacity of the sharpening layer
08:00 Sharpening in only one direction
09:50 What is Grain Merge doing?
11:00 How does this work?
14:50 Scripts at the http://registry.gimp.org
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