Features

You could be forgiven for assuming that sharpening is all about fixing photos that aren't properly focused. In reality, there isn't much you can do for photos that aren't properly focused. That's why it's so important to focus your camera properly in the first place. Of course, you'll usually be relying on autofocus to do this for you - which is why it's so annoying when it doesn't work as you expect. Sorting that out, though, will take another article.

It's true that a bit of sharpening can make the difference between a reasonably well focused shot and a really crisp one. That's one reason to use sharpening, but there are two more that are just as important. Firstly, when you print a photo, it won't look quite as sharp as it did on your PC screen. That's because the printing process breaks it down into clusters of ink dots, which tends to create a slightly fuzzy effect. This will be minimal if you're using a top-quality high-resolution inkjet, but more noticeable with commercial offset printing (as in this magazine) or any relatively coarse printing method. To counteract this, the image needs to be over-sharpened before it's output.

Secondly, with today's digital cameras offering massive resolutions as a matter of course, you'll often be printing a picture smaller than its ideal size. Having more pixels than you need is a lot better than less (try to blow up a photo too big and you get that horrid blocky effect), but what's often overlooked is that when a massive image is reproduced smaller, it appears less sharp. Again, the solution is to sharpen it as you reduce the size.

The pro sharpening tool is called Unsharp Mask, and here's how to get the best from it.

Sharpening down

When you need to reduce an image in size, sharpen it at the same time. Use the Resize or Image Size command in your image editor (Alt+Ctrl+I in Photoshop Elements) to 'resample' the photo. In the dialog box, enter your desired size in centimetres or inches, then switch the units to percent to see how much smaller this will be. If it's more than half the area of the original (71%), go back and sharpen the pic, using a slightly larger Radius than normal, then resample, then if necessary sharpen again with a small Radius (as little as 0.5 pixels) for a final polish. If you're downsizing further than this, do it in steps, reducing to no less than 71% each time, sharpening again at each stage. Try it and you'll be surprised what a difference this can make to the end result, especially when printing pictures very small or creating miniature graphics for websites.

	1 Unsharp Mask isn't the most intuitive name for a sharpening command, but it reflects a clever principle that's used to make photos look crisper. Essentially, it works by combining the image with a blurred copy of itself. Because details and edges are more strongly affected by blurring, they're enhanced by the process, as seen here.

	2 The Unsharp Mask tool (found under Enhance in Photoshop Elements 5, or on the Filter menu in other versions) usually has three controls: Amount, Radius and Threshold. Set the zoom level of your image or preview to 100% so you can see what you're doing, then set the Unsharp Mask controls to Amount 100%, Radius 1, Threshold 0.

	3 Increase the Radius (if necessary) until you see an improvement. Larger and/or fuzzier images will need more, but you shouldn't have to go beyond about 4 pixels. A decimal between 1 and 3 is often the sweet spot. Then adjust the Amount: more than 100% if you need a strong effect, or less if it's just a subtle polish for a perfect pic.

	4 Sharpening may bring out unwanted detail in background textures, or reveal noise (graininess) or other imperfections in the photo. That's where the Threshold control comes in. Increasing this will return less prominent edges and details to their original state while keeping the sharpening effect on major features. Again, judge by eye.

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