I came across this sharpening trick that sharpens the Red Channel in Luminosity mode.and want to pass it along.Go to Layer-Duplicate Layer-click OK then change the Layer mode from Normal to Luminosity.Click on Channels and choose the Red channel.Go to Filter-Sharpen-Unsharp Mask. Set the radius to 50 and the amount to 50 then click ok.Go to Layers-Opacity and play with the slider until satisfied.
The red channel here acts as the sharpening mask. For this type of sharpening you may also want to look at converting the image to Lab mode and sharpening the "L" channel.
The problem with sharpening a color channel is that colors on the edges of different objects will be changed. Sharpening only the "L" channel, which is the luminesance, does not alter the color as it is grey tones of equal color intensities. Human eyes do not detect sharpness in colors, only in back and white.
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The problem with sharpening a color channel is that colors on the edges of different objects will be changed. Sharpening only the "L" channel, which is the luminesance, does not alter the color as it is grey tones of equal color intensities. Human eyes do not detect sharpness in colors, only in back and white.