Almost every RAW file requires some degree of sharpening to counter the effect of blurring that occurs at some stage of image capture or image processing. But when do you apply the sharpening? In Camera Raw or later in Photoshop? The answer isn't as straightforward as you might think. The fact is, there are compelling reasons to apply some sharpening to your RAW file using Camera Raw. There are also compelling reasons to turn off sharpening in Camera Raw, wait until your RAW file is open in Photoshop, and then apply sharpening via the new Smart Sharpen filter or one of the many third-party sharpening tools. It really depends on what you want: optimal workflow or ultimate flexibility and user control.

To sort through some of the misunderstanding about when and how to apply sharpening, I find it useful to break sharpening down into three general categories, applied sequentially in the order listed here:

  1. Capture sharpening: sharpening that compensates for purposeful blurring at either the camera level or during RAW conversion.
  2. Cosmetic sharpening: sharpening applied to a specific part of an image and not another, i.e., eyes, but not blemishes.
  3. Print or output sharpening: final sharpening based on a specific size and destination of an image.

Since we're talking about processing RAW files, I'm going to emphasize capture sharpening.

Capture sharpening is best understood by looking at an image with no sharpening applied. For example, look at Figure 1. The photo was taken with a Fuji FinePix S3 Pro SLR using a very high-end Nikon lens for optimal sharpness. It was shot at f/8 at 1/250th of second and carefully focused. I used the Camera Raw sharpening slider to turn sharpening completely off, and the resulting image is not an accurate representation of the scene as I shot it. Also, it doesn't do the equipment I used justice.

Figure 1
Figure 1: An image in need of sharpening.

Ok, so we agree this image requires sharpening, but what's the best way to do it?

I recommend using the sharpen feature in Camera Raw whenever you are processing large numbers of RAW files, or when speed is an issue and you simply want to create an image that appears sharp on a monitor. I say this knowing full well that you'll likely need to use other sharpening methods to apply Cosmetic or Output sharpening at a later point. I recommend using the Smart Sharpen feature in Photoshop if you have a problematic image that Adobe Camera Raw sharpening doesn't improve, or if you have the time and desire to perfect a particularly special image. (The Photoshop Smart Sharpen filter can also be used effectively for both Cosmetic and Output sharpening.) For this example, let's use Camera Raw.

Capture Sharpening in Camera Raw

A sharpening value is automatically applied to a RAW file when you open it in Camera Raw for the first time. More often than not, the default Camera Raw sharpen setting works pretty darn well. There are good reasons for this. First, Camera Raw automatically applies a sharpening factor based on relevant data specific to a particular digital camera. Second, sharpening occurs only in the luminous channel, thereby reducing the chance of unwanted artifacts. Third, Thomas Knoll, a certified genius and creator of Photoshop, built the Camera Raw sharpen algorithm from scratch.

Of course, if you have the time or inclination, you can tweak the Camera Raw sharpen settings and apply your custom settings to other images taken with the same digital camera.

For an example of how to adjust the sharpness setting, I'll use the image in Figure 2, which has a combination of detail (trees) and continuous tone (sky). I want sharp, clearly defined branches, but I also want to avoid adding noise or artifacts to the sky.

Figure 2
Figure 2: I want to define the branches without adding noise to the sky.

  1. I set the white balance and exposure controls. In this case, the Auto settings are fine. I check these settings first because it's easier to judge detail appearances when the colors and exposure are correct.
  2. I identify a representative area of the image that contains both detail and continuous tone. Using Camera Raw Magnify tools--either the Zoom tool or the Zoom level controls--I enlarge the image at least 100 percent and use the Hand tool to position the area I wish to observe in the middle of the Camera Raw window, as I've done in Figure 3.

Figure 3
Figure 3: I zoom in on a section that has both detail and continuous tone.

  1. I select the Detail tab in the Camera Raw controls, shown in Figure 4.

Figure 4
Figure 4: The Camera Raw Detail tab.

  1. Unless you changed the number previously, the sharpening setting is always 25, regardless of which digital camera you use. I find it useful to start by sliding the slider to 0 and examining the image to establish a baseline for future sharpening (see Figure 5).
    (Keep in mind; the effect of no sharpening will vary from camera to camera. With some digital cameras, the effect is barely noticeable. With others, it'll appear extremely noticeable.)

Figure 5
Figure 5: I start with the Sharpness slider set to 0.

Remember, when Preview is deselected you see a representation of your image determined by Camera Raw settings applied when the file first opened and before you changed anything. This means if Sharpening is set to 25 at Camera Raw startup, then when preview is deselected you are actually viewing your image with some sharpening applied.

  1. Move the slider to 100 percent (see Figure 6), which obviously is way off. Again, I'm going to the extreme to get a sense of the range I have to work with.

Figure 6
Figure 6: I move the slider all the way to 100 to get a sense of the other extreme.

  1. Through trial and error, I finally come up with the number 40. You can see in Figure 7, I now have the right balance between sharpness of the branches, with no noticeable noise added to the sky. In general, don't go too far with sharpening. It's always best to err on the side of caution. If you overdo it, future Cosmetic or Output sharpening will suffer.

Figure 7
Figure 7: I finally arrived at 40 for the right balance.

Apply Sharpening to Preview Images Only

You can set Camera Raw to apply sharpening to the preview images only. However, when you open the image in Photoshop, the image will open with no sharpening applied. This allows you to see the effects of sharpening on your other Camera Raw adjustments. To do this:

  1. Select Preferences from the Settings flyout menu or from Camera Raw Preferences in Bridge.
  2. Select Apply sharpening to Preview images only from the Preferences dialog box, shown in Figure 8.

Figure 8
Figure 8: The Camera Raw Preferences dialog box.

Fixing the Effects of Over Sharpening

For some images, such as the moonscape shown in Figure 9, you can use Camera Raw's Luminance Smoothing controls to diminish artifacts caused by over sharpening, or, as in this case, a combination of sharpening and a high 800 ISO.

Figure 9
Figure 9: Luminance Smoothing can reduce the effects of over sharpening.

To do this:

  1. Enlarge your image using magnification controls.
  2. Select the Detail tab.
  3. Find the optimal sharpening using the Sharpness slider.
  4. Increase the Luminance Smoothing slider slowly, observing the effects. Stop when you achieve a balance between edge sharpness and diminished noise or artifacts in the continuous tone areas. In the example in Figure 10, a setting of 40 worked.

Figure 10
Figure 10: The right balance found with the Luminance Smoothing slider.

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