articles/Landscape/post-pro-page4

The First Stage of Post-Processing - part 4 of 1 2 3 4 5 6

by Mike McNamee Published 01/04/2015

Holding down the Alt key to 'highlight' the effect of Radius settings is a poor witness to what is going on. In the composite below Radius settings of zero, 0.8 px and 3 px are shown (bottom upwards). There is relatively little difference especially as values between 0.5 and 1.0 are optimum. This leads to the conclusion that the only way to really differentiate between settings is to make prints!

Pre-Sharpening
It is a fundamental feature of sharpening that you cannot perfectly judge the effect without making the final size of print. This, however, is a counsel for perfection and, with experience, you can make an attempt based on previous efforts.

In best practice you 'pre-sharpen' your RAW image and follow this by 'output' sharpening. Digital cameras inherently create slightly soft images. The sharpening function in ACR is very adept at pre-sharpening RAW files. We will need to sharpen the fully processed file once we are finished with it in Photoshop, but then sharpening will be relative to the size and resolution of the output.

There are four sliders that we can adjust. Amount and radius affect the amount of sharpening; detail and masking are known as suppressioncontrols that constrain the effect of the two previous controls. Amount is akin to a volume control. How much sharpening do you want to apply? I find that between 50% and 100% is where we have the best effects (using a Nikon D800). You can go higher if you want, but be careful. One of the greatest sins of post-processing you see is over-sharpened files, and this is only pre-sharpening. We will do more later in Photoshop.

The radius filter is very important and determines the width of the halos generated around the edges in a photo. A small radius will pick out fine detail and a high radius will have the opposite effect. Generally I use 0.8 to 1.0. The radius setting is resolution dependent, a high-resolution file can accept a higher value than a low-resolution file. This is also true for subsequent, Photoshop sharpening where files for web use (for example) require the smallest radius setting available if over-sharpening is to be avoided.

Now the so-called suppression controls. The details slider suppresses the halo effect in your image. As you change this slider, keep the ALT key depressed. Again you will see a greyscale image. The lighter (also white) the representation, the more the effect the radius slider has. Set to zero, the whole image is affected. Typically I set the detail slider to between 50 and 60.

BELOW: Holding down the Alt key to 'highlight' the effect of Radius settings is a poor witness to what is going on. In the composite below Radius settings of zero, 0.8 px and 3 px are shown (bottom upwards). There is relatively little difference especially as values between 0.5 and 1.0 are optimum. This leads to the conclusion that the only way to really differentiate between settings is to make prints! The masking slider protects those areas with a flat tone from being sharpened. This would be useful and effective in a portrait for example where you didn't want the majority of the face to be sharpened. In this image I have set it to 10 as there are lots of small imperfections in the bonnet of this rusty old car. If everything were super sharpened it would look very gritty indeed. For a landscape image I tend to leave masking set to zero - ie everything is sharpened.

As with all controls, depressing the ALT key as you change the slider shows you the level of effect the slider will have. White has full effect and blacks no effect.

• The First Stage of Post-Processing page 1
  
• The First Stage of Post-Processing page 2
  
• The First Stage of Post-Processing page 3
  
• The First Stage of Post-Processing page 4
  
• The First Stage of Post-Processing page 5
  
• The First Stage of Post-Processing page 6
  

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