I see what highpass does when I select it, but what's next? How do I apply it t improve the image I'm working on?
Thanks in advance.
I use the High Pass filter for sharpening quite a bit.
Here is how I do it. (Note that you only need to run through this routine one time. When you are finished, save it as a Setting.)
Add a High Pass Filter to the image: Adjust>Focus>High Pass
In the Edit List, open the Opacity controls for the High Pass edit (that is, click the Opacity triangle in the lower right of the High Pass edit step box).
Set the Opacity mixer to Luminance and Chrominance mode.
Set the Chrominance opacity to 0%
Set the Blending Mode to Overlay.
Click OK in the Opacity dialog box.
Open the High Pass edit step (by clicking the triangle on the lower left side of the High Pass edit step box). This brings up a Radius slider. Move the slider left and right until you achieve the desired result.
Note that you will probably get the best results (in my experience) for most images with a radius setting of between 0.8 and 2.0. Anything more is going to look bad, in my opinion. Images that are in good shape to begin with will probably not tolerate a Radius setting over about 1.2 or 1.3 before they start looking over-sharpened.
I generally use this sharpening technique later in the process, after I apply a gentle, global capture sharpening routine earlier in the workflow. I also use High Pass to sharpen selected areas, especially eyes and other facial features that I want to stand out; once I apply the filter, I paint it in where I want it.
As noted above, once you have gone through all of these steps, it would be a good idea to save that edit step as a Setting, which you can call up and use later. Before doing that, however, I suggest that you move the radius slider to between 20 and 30 pixels (I set mine at 25) and then save it as a Setting. That way, when you load the Setting later, it starts out really high. Just open the High Pass edit step to bring up the Radius slider, and move the slider back down.
My main source for this technique is RealWorld Nikon Capture NX by Ben Long, p. 188.