One of the least understood aspects of finishing your photographs for presentation is sharpening. Unfortunately the language used to describe it is very non-descriptive and confusing—quite the opposite of sharp, if you will. Sharpness in photo processing has nothing to do with you how clearly your camera has captured the details of a scene. The qualities of your lens and camera are really terms of resolution. A nice f2.8 image of flowers can be exceptionally crisp in detail for the areas in focus and yet still have great bokeh in the background.
Sharpness deals more with how the image interacts with the viewer’s eye and the medium it is presented on. We shall use as our definition “the apparent increase in contrast between edges in an image”. Luckily for us our tools LR and Photoshop are pretty smart in figuring out how to make our pictures look better.
Knowing how you intend to display your image makes a huge difference in how you apply the sharpening. If it is for print, you want to think about how big a photo you are going to wind up with. Small changes on a small image may not even show up. On a web page or a digital viewer where people can zoom in, too much sharpening can make you subjects look brittle and unrealistic.
Sharpening can be applied globally and through brushes, filters and masks can also be selectively applied. Almost every image should be sharpened at least once, most often twice, but your best images should get three different techniques applied.
Starting in LR, after you’ve made your initial adjustments in the Basic Panel in the Develop Module, you can proceed down to the Details panel. There are four controls available to work with, plus the little cross hair. If you drag the cross hair onto the main image it will show that section of the image in the sharpening window. How much should you sharpen? As with most visual arts, the answer depends on what effect you are trying to achieve. People, especially women’s faces should have less, while it can add “character” for older men’s faces. Inanimate objects can take more but it becomes obvious when you have over sharpened. The definitions of the four sliders are best described by the Adobe Help page http://helpx.adobe.com/creative-suite/using/sharpening-noise-reduction-camera-raw.html:
Adjusts edge definition. Increase the Amount value to increase sharpening. A value of zero (0) turns off sharpening. In general, set Amount to a lower value for cleaner images. The adjustment is a variation of Unsharp Mask, which locates pixels that differ from surrounding pixels based on the threshold you specify and increases the pixels’ contrast by the amount you specify. When opening a camera raw image file, the Camera Raw plug-in calculates the threshold to use based on camera model, ISO, and exposure compensation.
Adjusts the size of the details that sharpening is applied to. Photos with fine details generally need a lower setting. Photos with larger details can use a larger radius. Using too large a radius generally results in unnatural-looking results.
Adjusts how much high-frequency information is sharpened in the image and how much the sharpening process emphasizes edges. Lower settings primarily sharpen edges to remove blurring. Higher values are useful for making the textures in the image more pronounced.
Controls an edge mask. With a setting of zero (0), everything in the image receives the same amount of sharpening. With a setting of 100, sharpening is mostly restricted to those areas near the strongest edges. Press Alt (Windows) or Option (Mac OS) while dragging this slider to see the areas to be sharpened (white) versus the areas masked out (black).
As you can see this image looks much crisper than what we started with.
Next time we will talk about the more advanced tools available in Photoshop.