Cim MacDonald mentioned image sharpening in her presentation at the September Ladysmith Club Meeting. Brad Grigor kindly extended the process and a couple of references for sharpening in Photoshop.
The method Cim uses for sharpening that works only on the luminance of the image and not the colours. Here are the main steps:
- Flatten your image
- Convert the image to Lab colour mode (Image > Mode > Lab)
- In the Channel Panel, select the L channel (which displays as a grayscale)
- Perform your sharpening (e.g. Unsharp Mask).
- Then convert the image back to RGB (Image > Mode > RGB)
This eliminates some issues of sharpening in RGB but it required Photoshop CS. It cannot be done in Photoshop Elements or LightRoom. Here are some informative links: http://photo.net/learn/digital-photography-workflow/advanced-photoshop-tutorials/sharpening-in-lab-color/
Here is a one of a series on sharpening options, even how to sharpen the luminance with the Lab mode. http://planetphotoshop.com/focus-on-sharpening-part-3.html