Sharpening - in camera vs Light Room

Sometimes I photos look soft. However, using Light Room, I find that same images can been sharpened quite dramatically.


How does LR do it? Does it actually alter the image or using special algorithm? I increased in-camera sharpness settings a bit but still I find that LR can make it more sharp compared to photos coming straight out of camera.

Sharpening a image is really just altering the pixels on the boundary between areas of medium and strong contrast. Increasing the "sharpening" is really just expanding this boundary depth from 1 pixel layer to up to a maximum of 5 (I think it's 5)
As for in-camera sharpening, if you're taking photos in RAW format, the sharpening only applies to the preview you see when looking at the image in camera. The sharpening does not apply to the RAW data.

AS Dave mentioned, sharpening deals with altering pixel boundaries. The problem is, as you sharpen significantly you can really put noise into places you didn't intend on sharpening. The truth is, what you want sharpened are usually the boundaries between color and pattern areas.

There's a mask slider in Lightroom that will limit the areas to which the sharpening is applied. You can see precisely what areas they are by holding down the Options (Alt) key as you slide to the right. Areas sharpened will be shown in white. Generally I find that when I sharpen in Lightroom I'll bring the mask to somewhere between 65 & 85 depending on the photo.

I will set radius to 1.3-1.5 as well for images over 20MP's. For less than that I usually go with 1.2-1.3. From there, play with the sharpening amount until is suits.