Capture sharpening
From Nikonians Wiki - FAQs, Photo Glossary, Good Photo Locations, Help
Capture sharpening is the application of a very small, controlled amount of sharpening to the entire image in order to cancel out the effects of anti-aliasing which tend to soften the image.
Capture sharpening should be applied immediately after the image has been loaded, and can be achieved through unsharp masking or with a deconvolution filter such as FocusMagic. Because the sharpening has to be applied exactly, it may be easiest to do it when in Photoshop with a script such as TLR's Professional Sharpening or Photokit Sharpener.
Achieving capture sharpening without special tools
Capture sharpening can be done in Adobe Photoshop in the following way. It may be more convenient to create an action to accomplish this.
First, build an edge mask. An edge mask is a mask where the edges are white, and everything else is black. The simplest way is to find a channel with good contrast and copy it as a mask, and then run the find edges filter, which is in the Filter>Stylise menu. You then need to invert this, as Find Edges makes the edges black and everything else white. Finally, to complete the edge mask, use levels to give good contrast where you want sharpening to take place — ie, real edges, rather than noise.
These are some typical level settings:
This is what you get — what edge detection finds, and what you have after you've inverted it:
Now, create a selection from the mask, and use it to copy the image (or the portions selected) to a new layer. Alternatively, copy entire image to a new layer, and use the mask as a layer mask. You may like to gaussian blur the mask by 3 pixels, or feather the selection the same amount.
Now, sharpen the layer using unsharp masking, sharpen at 200% with no threshold and a radius of 0.4 pixel.
Finally, blend the layer with blend mode — luminosity — with an opacity of about 65% and the Blend if Gray set as follows:
Inspect the image carefully, and tweak if necessary. When you are satisfied, you can merge the layers.
This should give a very small, but discernible amount of sharpening, which means the image is now prepared to be worked on.
Later in postprocessing you may want to apply creative sharpening and, if you are to print the image, you will want to apply output sharpening as the very final process.
