The Black Art of Sharpening

My biggest problem when starting out with post processing digital images was that of sharpening. I simply could not seem to strike a balance that for me, exhibited the right amount of sharpening without too much destruction. I guess this, and other post processing routines are down to personal preference; what I consider being enough will not be to everyone’s personal taste. Me? Well, I like my images to be ‘film like’ in their appearance, and the right amount of sharpening is fundamental to achieving this result.

My main post processing software is Lightroom 3.5 or 4.0 (the sharpening examples given below are relevant to Lightroom only), depending on what computer I am working from.

Sharpening results are dictated by four elements;

  • Amount
  • Radius
  • Detail
  • Masking

Amount has values between 0 and 150; the sharpening algorithm is looking for edges to which additional contrast can be applied to make the final image appear sharper. The Amount dictates precisely how much to apply, and this depends on the type of image that is being processed. For example, I tend to use less sharpening when processing portraits than I would for landscape images. Therefore the amounts set are 20 and 30 respectively.

Radius requires me to define how far out from the edges I wish to sharpen. Values range from 0.5 to 3.0, and the higher the value, the more I am likely to see a halo effect which can be particularly apparent where subjects against solid colour backgrounds (i.e. blue skies) are concerned. Therefore caution should be exercised when using this in the above scenario. For portraits I use values between 1.2 and 1.5, as this helps smooth the transition between sharp areas. My landscape setting is less than this, 0.7 to 0.9 is what works for me.

Detail essentially looks for the amount of things to be sharpened; Values range from 0 to 100 and I tend to prefer  a low value of around 15 for portraits, as this ensures that large areas of skin or fabric do not get sharpened too much.  My landscape value is set to between 30 and 40, as this applies sharpening to more areas of the image, and does not confine it to just the contrasting edges (as it would when setting the value to 15).

Masking is good for recovering areas that may have been over sharpened by zealous use of the Detail control. It is also good for smoothing areas of skin, reducing the visibility of blemishes in the final image. Values vary from 0 to 100, and I favour a setting of around 50 for portraits and do not use it for my Landscape images (value is set to 0).

My workflow uses some custom pre-sets, based on what works best for me, and the sharpening values form part of each pre-set that in most cases achieves the desired result. However it is worth considering each pre-set as simply a starting point, apply it and zoom the image up to 1:1 for closer inspection of the results. Micro tweaking of Amount, Radius, Detail and Masking can then be applied before moving onto the next stage of your workflow.