Pete's Creative Sharpening Tutorial
The Edge Mask Method (CS2)
This is a sharpening method that is suitable for use where there are highly defined edges in a photograph - mostly suited to urban/mechanical/industrial type shots, and also macro/flower shots too. Basically things that don't involve fur or feathers!
It works by targeting the most highly defined edges in a photograph and applying high levels of USM sharpening to them. Since the areas being worked on are so narrowly selected, you won't get any adverse effects on more subtle areas of the shot (like background blur and finer details)
1. Open a shot that has nicely defined edges. Perform whatever manipulation tasks you need to do (levels/contrast/whatever). Then flatten whatever layers you have left over.
2. Select the entire shot and copy it to the clipboard (Ctrl+A, then Ctrl-C). Then open up the "Channels" palette and create a new channel. Do this but clicking the small button at the bottom of the "Channels" palette (). This results in a black channel called "Alpha 1"
3. Now paste the contents of the clipboard into this new channel (Ctrl+V). The image will appear in greyscale (this is normal).
4. Now run the Filter->Stylize->Find Edges filter. This will give you the beginnings of the edge mask.
5. The next few steps will isolate the most defined edges and fade out the finer detail like the speckles on the tyres and grain on the struts. If these were sharpened to the level that we're going to apply, they'll look pretty nasty.
Open up the levels control (Ctrl+L), and move the left slider inward toward the right. You'll notice that this increases the contrast for the edges, making them appear darker.
Now move the right hand slider inward. You'll see that the finer detail will start to disappear. Start off with about 25% inward for both sliders, but you'll see what detail you'll want to accentuate and what you'll want to lose.
See how moving the right slider in has made much of the grain on the struts disappear, and also most of the brickwork in the background, and the detail on the tyres. Press ok on the Levels dialog when you're done. Don't worry if there's still detail visible that you might not want sharpened, that will go in the next steps.
Next we run a small Gaussian Blur (Filter->Blur->Gaussian Blur). This serves to widen some of the edges further (so that the resulting selection has more area in which to apply it's sharpening halos). For full resolution photos, a setting of 2.0 pixels is fine, you only want the effect to be minimal.
Press 'OK' on the Gaussian Blur dialog when you're done.
6. Open the Levels dialog again (Ctrl+L). Move the sliders in even further. You'll see the more defined edges get blacker again, and the finer detail will again fade into nothingness.
Press 'OK' on the Levels dialog when you're done.
By now, you should get a good idea of what parts of the photo are going to be sharpened. As you can see, the areas are now very defined. At this stage, you can optionally use a hard white brush to further blank out any detail you want to exclude from the sharpening action.
7. Now, to create the actual sharpening mask, we invert the mask, and then load it as a selection. Use Selection->Invert (or CTRL+I) to invert the mask.
8. Now to load the mask as a selection, press the small dotted circle at the bottom of the "Channels" palette (). You'll see a jumble of marching ants appear on top of the mask. Now hit the top channel (RGB) to see your original photo in colour with the selection overlaying it.
You can use the marching ants as a more visible guide to where the sharpening will be applied. If you need to adjust the selection, simply de-select (Ctrl+D), select the mask again, and paint with a black brush (because the mask is now inverted) over the areas you want to deselect. Then you can load the selection again.
10. Now the actual sharpening step!! First off, hide the selection (so the marching ants don't hide the sharpening view from you), do this by pressing Ctrl+H). Open up the Unsharpen Mask dialog (Filter->Sharpen->Unsharpen Mask).
Use a large amount (250-500%), you can get away with this because the effect is so targeted. Use a radius of 1.0 and a threshold of 2. Don't worry about the mess in the Preview screen of the USM dialog, that only shows you the underlying image (with no mask applied).
Sit back and enjoy the sharpness...