I often find it quite difficult to know exactly where to set the sharpening sliders, as the adjustment effects are so subtle. Well, hidden in this panel is a neat little feature that makes adjusting these setting so much easier.

If you hold down the Option key (Mac) or Alt key (Windows) while moving the Radius, Detail and Masking sliders, then your image is overlaid with a greyscale mask that shows you exactly how much impact the slider value will have.

In the screen shot below I am adjusting the Radius value, with the Option key held down as I move the slider.

The radius setting dictates how broad either side of an edge the sharpening effect will be. The white parts of the image above visually indicate the radius setting. In the above screen shot I have got the radius set to quite a high value to make it easier to see in the screen shot.

The next screen shot is for the Detail setting. Once again I have set the value quite high so you can see the impact. The detail setting controls which edges are effected. A higher detail setting will pull in edges with lower contrast – i.e. finer image detail.

The final sharpening setting is Masking. This setting allows you to exclude, by way of a mask, areas of even tonality, like sky. You don’t want to sharpen flat tonal areas, but a high Detail setting may have introduced sharpening in these areas. So you use the mask to block out the sharpening effect. It works and looks much like a layer mask in Photoshop.

I use this trick all the time now, as it makes for a much more intuitive experience setting the sharpening slider settings. Using this trick in combination with the zoomed in preview thumbnail at the top of the details panel now makes sharpening settings a breeze.