Sharpening

Adobe Camera RAW’s Clarity control (4.1 and above) is the first tool for sharpen your photo.
Unfortunately Photoshop is not able to adjust it after the RAW processed, but Lightoom yes.

However Clarity can increase the local contrast and sharpen the edges, it’s not able to remove blur.
That’s the job of the Unsharp Mask or another sharpening methods of Photoshop.

Sharpening in LAB mode, on the L (Lightness) channel provides superior results, with less artifact.
However sometimes the old RGB method will work out better for you, but the LAB sharpening is much more natural with fewer halos and color oddities.

1. Convert to Lab

Convert the proccessed RAW to LAB Color mode (Image/Mode/Lab Color) then select the Lightness channel in the Channels palette and apply the Unsharp Mask filter.
It’s important that haven’t got any adjustment layers yet, because with the converting you’ll lose any RGB-specific adjustment.

If you already have, then make a copy of the visible image by doing a “Stamp Visible” command (Ctrl+Alt+Shift+E). This gives us a single layer that contains all of the underlying adjustments we’ve applied. Now take this layer and duplicate it to a new document.

The lightness channel contains all of the light and dark tones in the image while avoiding any noise caused by the color channels. Sharpening works by darkening the darks and lightening the lights at their boundaries. Any color noise will cause noisy sharpening, so we’ll just avoid it altogether. In this example, I’ll use the Unsharp Mask to sharpen the image. In truth, you could use whatever method you prefer in place of that — the key is to do it on the lightness channel.

2. Sharpen the Lightness channel

So switch to the channels palette and select “Lightness”. The “a” and “b” channels should be deselected and your image should look like a black and white photo. Now, apply your sharpening directly to that channel. For the Unsharp Mask, you can find it under Filter >> Sharpen >> Unsharp Mask. I typically start with an amount of 100%, a radius of 1.5%, and a threshold of 1 — but every image requires different settings, so don’t just assume that those numbers are the best. Once you get the sharpness where you like it, apply the filter and reselect the “LAB” channel in your palette.

3. Go back to RGB

Now go back to RGB (Image/Mode/RGB Color).

If you made a new document becasue your adjustments, go back to your layers palette and copy that layer back to your original image — it should convert itself back into RGB when you copy it over.

Once you’re back in the original image, you’re pretty much done with the adjustment. You can now toy around with masking and opacity settings to get the final look you’re after. Sometimes I’ll over-sharpen the sharpest areas just a bit then go back and partially mask out those areas that didn’t need much sharpening. This allows me to properly sharpen the majority of the image.


source, edited by Celestin de Villa

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