You should ensure that you get your image sharp in camera (see this blog post) – you cannot rescue a blurred image by sharpening it. However, you can make a sharp image look sharper and bring out details by using a sharpening tool. Bear in mind that if you are shooting JPEG files sharpening is applied in camera and you don’t need to do much, if any at all, to your image. However, if you are shooting RAW files, then you will need to apply some sharpening.
What does sharpening do? It makes edges appear crisper and sharper by darkening dark pixels and brightening light pixels. If you over sharpen, the image starts to look unnatural, with white edges as in the version below where I’ve applied 100% sharpening in Snapseed. I usually don’t use much more than 25%.
SNAPSEED: The Details tool has two forms of “sharpening” available:
- Structure: this applies more contrast to the image to make details more apparent.
- Sharpening: this makes the difference between the edges of objects more obvious.
Always enlarge your image to 100% so that you can see the effect of any sharpening you apply. Look particularly at hair when you are editing a portrait.
Sharpening should be applied at the end of the editing process whatever software or app you are using.
Be aware that as a JPEG is sharpened in camera, you are sharpening it for the second time – fine if it makes it look better, but if you are using any 3rd parties to print etc, some of them automatically apply sharpening – resulting in your image being sharpened 3 times. Take this all into consideration when you apply sharpening. I shoot RAW files, apply sharpening at the end of the editing process and then switch off any 3rd party sharpening if I can.
You may see slightly different terms used in programmes like Photoshop (& Elements) and Lightroom. The term Unsharp Mask is a common one and comes from a technique used the darkroom when processing film. Many photographers use this tool as it offers sliders where you can change parameters such as Amount, Radius, and Threshold. If you’d like to know more then take a look at this fairly no nonsense blog post or do some Google searches. I have to confess to using Photoshop Actions which include sharpening and I usually reduce the strength a little, whilst looking at the image at 100%.
Hope that’s all been helpful – sharpening is a topic that makes seasoned photographers groan. But the biggest sin is to over sharpen, rather than under sharpen. Less is More!