Using Output Sharpening
To set output sharpening, click the blue underlined text at the bottom of the Camera Raw window to open the Workflow Options dialog (see Figure 4); then choose a sharpening option from the Sharpen For pop-up menu. If you choose any option other than None, you can then choose a degree of sharpening from the Amount pop-up menu.
Figure 4 You control output sharpening with the Sharpen For and Amount pop-up menus in the Workflow Options dialog.
Sharpen For Options
At first glance, you might think that the Sharpen For choices are way too basic: Screen, Glossy Paper, and Matte Paper. But don't dismiss them out of hand—the choices are far more sophisticated than they look. When you choose a sharpening option, you aren't applying a single hard-coded number to the image. Instead, each option calculates a sharpening amount that's based primarily on the resolution and pixel dimensions of the image, and also on the medium represented in the name of the Sharpen For setting you chose.
Let's run through an example using an 8-megapixel image (3456 × 2304 pixels) set to 240 ppi in Camera Raw Workflow Options. If you choose Glossy Paper, Camera Raw applies a sharpening value that it thinks is optimal for glossy paper stock at 240ppi. If you change the resolution or the image size, Camera Raw calculates a different sharpening amount even if you don't change the Sharpen For setting—that's why you don't see a static number in that pop-up menu. But this also means that if you save an image at those Workflow Options settings and then you use the image for screen display or you print it at a different size or resolution or on matte paper, the output sharpening applied to it will be wrong.
How does Camera Raw know what an optimal sharpening value is? It uses methods similar to the tried-and-true sharpening algorithms used by PhotoKit Sharpener, a Photoshop plug-in developed by PixelGenius LLC. Because the proper amount of sharpening is best determined by the final output conditions, the goal of the technology is to let you apply sharpening by specifying your output conditions instead of by facing an Unsharp Mask dialog that you have to figure out yourself. PixelGenius was founded by Photoshop experts, including Jeff Schewe (author of Real World Camera Raw with Adobe Photoshop CS4) and Bruce Fraser, so when you apply output sharpening in Camera Raw it's a little like having the best minds in the business figure out your sharpening settings for you.
Proper sharpening isn't a purely technical decision; there's an aesthetic component as well. If you sharpen a photo for a specific type of output and show the output to a range of professionals, you'll get a sort of "Goldilocks effect": Some of them will tell you it's undersharpened, some will say it's oversharpened, and some will say it's just right. The Amount pop-up menu exists to account for a reasonable range of personal preferences. The Standard setting is a technically sound starting point when Sharpen For is set correctly, but if you find that you regularly prefer less or more sharpening than you get from the Standard setting, choose Low or High from the Amount pop-up menu.
Because Amount is about personal preference, the first time you use it you may not know which setting you'll prefer. Run some output tests at all three settings to determine which Amount setting is right for you.