Invert Sharpening in Photoshop:
Make New Action – subscribe it to an f key. Hit record ….
1. Duplicate image layer twice – Ctrl J
2. Change blend mode of top layer to Vivid Light and rename Vivid Light
3. Next layer change to normal and name it Normal – leave background layer
4. Invert Vivid Light layer – ctrl + i
5. Reselect blend mode as Vivid Light (now grey) if necessary
6. Filter – convert to smart object – OK
7. Filter – Blur – Gausian Blur – increase radius (max 3-3.5) until sharp images just appears
8. Hold down Shift and select Vivid AND Normal layers
9. Ctrl + g to group them together (vivid, smart, gaussian blur and normal)
10. Blend mode automatically changes to Pass Through
11. Change Blend mode to Overlay – don’t flatten.
12. Stop Action
Now, to sharpen an image simply hit the f key. This is maximum sharpening applied.
Go to the Layer Palette (in the Window menu).
Reduce opacity to whatever looks right. Less is often more.
Flatten Image (in Layers Menu) and use the History Brush (Y) to paint back areas to be unsharpened.
All the best!
Scott