In a perfect world, all the photos we take would emerge from the camera perfectly formed, sharp as a tack, and ready for framing at the Louvre.
Of course, reality is anything but: Most digital cameras take photos that are a tad "soft," which is why it's often a good idea to sharpen your images a little before printing or sharing them.
Camera or PC?
One way to sharpen your photos is to let our camera do it for you. Check out your camera's user guide and you'll probably find a way to automatically sharpen every photo as it's taken. That's a simple and painless way to give all your images a little "bite," but it's not perfect. You have no real control over how much sharpening is applied — and worse, the sharpening happens to the entire photo. The foreground, background, sharp and intentionally blurry parts alike are all equally affected.
Instead, I recommend that you sharpen your photos by hand, using the Unsharp Mask tool in your favourite photo editor. To try it out, open an image file in your photo editor. I'll use Adobe Photoshop Elements, but you can get the same results with almost any program. For this example, I suggest picking a photo with a sharply defined subject and an out-of-focus background.
Sharpen in a Layer
At this point, you could simply sharpen the entire photo using Unsharp Mask and be done with it. You'd have more control over the amount of sharpening than a digital camera's automatic sharpening mode affords, but you're still applying the effect to the entire image. That's not what we want: You'd be adding local contrast everywhere in the image, which would fight with the natural blur caused by the shallow depth of field.
For more precise control, let's sharpen the photo in layers. To do that, in the menu, choose Layer, Duplicate Layer, from the menu and click OK. You now have identical copies of the photo stacked in layers. In the Layers Palette on the right side of the screen, click the top layer to make sure it's selected, and then choose Enhance, Unsharp Mask.
Choose whatever sharpening settings you like best. In general, you'll want to set Amount to between 100 and 200, Radius between 1 and 2, and Threshold between 0 and 10. Higher Amount and Radius values increase the sharpening effect, but the lower the threshold, the stronger the effect.
Erase the Background
That's a lot sharper, but the background has lost its soft focus. No problem: Since we sharpened the top layer only, we can selectively remove the effect from the parts of the photo that we want to soften.
There are two ways to erase unwanted sharpness. You can turn off the underlying layer, or leave it turned on. If you turn off the layer as I recommend, it's easy to see what you're doing because the picture disappears wherever you click with the eraser tool. If you leave the layer turned on, the effect is more subtle, but you'll see the effect as you click around with the eraser tool. Confused? Just try it out and you'll see what I mean. Let's start with the bottom layer turned off: In the Layers Palette on the right side of the screen, click the Eye icon in the bottom layer. Next, in the toolbar on the left side of the screen, choose the Eraser Tool (it's 16th from the top).
We'll want to soften the edges of the brush so there's a gradual shift from hard to soft when we use the tool. In the brush presets drop-down menu in the toolbar at the top of the screen, choose a soft-edged brush such as number 21. You'll also want to increase the size of the brush. For my sample photo, a good size is about 70 pixels, but you'll need a larger brush if you work on a many-megapixel photo. Now paint away the top layer in the regions that you want to appear blurry. In my case, I need to paint around the boat, as I show in my screen shot.
When you're done, click the Eye icon in the bottom layer again to see the results, then save the finished image. Here is what my final image looks like.
After trying that method, "undo" the erasure and do it again — this time without turning off the bottom layer. You'll see the blur peek through immediately as you use the Eraser Tool.
Now you've tried the two erasure methods, just use whichever approach works best for you.