SwingBopper wrote in post #6816436
Bill, that's a very nice edit; but why sharpen only 2 color channels? And how do you just sharpen one color channel and not the whole image? And finally would you explain "output sharpening". The only sharpening I have done is in Photoshop.
That is a tip that I picked up from some of the guys in the bird forum. First of all, to access the color channels, simply select the Channels palette and then click on the desired color channel. When finished, click on RGB channel and then return back to the Layers palette. The amount of sharpening is normally very subtle -- set Amount to 50, Radius to 0.3, and leave the Threshold at 0. Pick a color channel -- usually red or green, but hardly ever blue, but it depends somewhat on the image and the desired end result.
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Since our vision sensitivity peaks in the greens, the green channel is usually where you will see the greatest amount of fine detail. The red channel tends to not reveal much fine detail, but does show boundaries of areas with differing amounts of luminosity. The blue channel is normally the most difficult to see any details because the sensitivity of our eyes decreases rapidly as we approach the limits of our color vision range. To me, the blue channel seems to separate luminosity into about three distinct levels.
In the above example, I would use the green channel if my objective were to mainly sharpen fine details. The red channel seems to emphasize contrasting areas such as the boundary between the sky and clouds (which is what you would expect of a red filter in B/W photography) and also help to accentuate the boundaries between the rocks and trees. About the only thing that the blue channel seems to be good for is to sharpen the boundary between the sky and top of the ridge. On the few occasions when I do apply USM to the blue channel, I normally reduce the Amount to 30 and increase the Radius to 0.8.
Output sharpening is just the sharpening that is done as the last step of editing before saving the image. The image must be set to its final size before sharpening is applied. The type and amount of sharpening depends upon the destination of the file. For a file that is to be printed, the typical recommendation is to sharpen until the image looks a bit "crunchy". If you were to apply the same amount of sharpening to a file whose destination were the web, it would look like heck, but a printer needs a bit of crunchiness to compensate for the slight softening that it causes as a result of inks bleeding into the paper a bit along with the various types of dot patterns and scattering that occurs in the printed output. The other type of standard workflow sharpening is capture sharpening which is done during the RAW conversion process and is a very subtle sharpening that is just enough to compensate for the softness that occurs during demosaicing. Additionally, creative sharpening is becoming more prevalent as a creative part of the workflow in Photoshop. Unlike the others, creative sharpening is normally applied selectively whereas capture and output sharpening are typically applied globally.
