Select the image that you want to sharpen and open it in the Develop module. To get a really close look at it, go to the view options on the Navigator panel at the top of the left sidebar and select the 1:1 view ratio, to see the image at 100 per cent size. If you want, you can zoom in even further with the expanded view options, but 1:1 should be enough.
Open the Detail panel, which you can find in the right-hand sidebar. We’ve already looked at the noise reduction functions but the Sharpening functions are in the top half of the panel. There is also a detail view available but to be honest it’s far too small to be much use. You’re better off checking your progress by zooming the main image.
Many digital SLRs have something called a low-pass filter that slightly blurs the image to prevent Moiré effects. By default, Lightroom applies a small amount of sharpening to all images to counteract this filter. Once an Amount is entered, Radius is 1.0 and Detail is 25 by default. If your DSLR doesn’t have this filter you can keep this at zero for maximum detail.
Like many adjustments, judging the correct level of sharpness is very subjective. To see what too much looks like, drag the Amount slider all the way to the right, to a value of 150. You can see that the high-contrast lines in the image now look harsh and jagged and the grain of the image has been emphasised, making it look noisy.
The Amount slider controls the degree by which the edge contrast is increased, while the Radius slider controls the distance from the edge that the contrast increase is applied. Keeping the Amount at 150, increase the Radius and watch the effect. Thick lines appear around the edge detail as the contrast area is increased.
The best way to apply sharpening is to make use of the split-screen comparison feature, and to carefully adjust the sliders. Start by slightly increasing the radius to 1.5 and then move the Amount slider to see if it improves the appearance. For most photos shot on a DSLR with a good lens you won’t need to apply much additional sharpening.
Another good way to compare the before-and-after effect of sharpening is to use the preview toggle switch in the top left of the Detail panel. All the Develop panels have this feature but it’s most useful in this case. Click the switch on and off a few times to see the effect with and without sharpening or noise reduction applied.
The third slider in the sharpening tab is Detail. Increasing sharpening can cause image noise to become more exaggerated, and the Detail slider lets you strike a balance between sharpened edges and visible noise. Try increasing the Detail slider all the way to 100 and back to zero to see the effect that this has on your image.
There is another alternative to help you judge the effect of the sharpening that you’re applying. If you hold down the left ALT key on your keyboard while adjusting the Amount slider, the image turns monochrome, whilst with the Radius and Detail sliders it shows just the edges that are affected. This special preview helps to show the effects more clearly.
The final slider is Masking. This removes the sharpening effect from some areas of the image. Again, hold down the left ALT key whilst moving the slider to see a monochrome preview. The effects of the other sliders will only be applied in the white areas of the image, so by adjusting the mask you can reduce the emphasis of unwanted effects.