Sharpening and Noise Reduction for RAW Images

If you're working with RAW images, then you have an extra set of sharpening and noise-reduction controls at your disposal.

Because the Sharpening Fodder image is a RAW file, the Adjustments HUD shows an extra controls group called RAW Fine Tuning. These controls provide an additional set of sliders for tweaking the appearance of your RAW files.

Note

If you have selected a RAW file and you don't see these sliders, it may be because the selected image has been set to use the Aperture 1.0 RAW converter, rather than the Aperture 1.1 RAW converter. The pop-up menu in the upper right corner of the RAW Fine Tuning controls group indicates which converter is being used. If the RAW Fine Tuning sliders are not appearing, choose 1.1 from the pop-up menu. If you don't see the RAW Fine Tuning controls group at all, it's because you have not selected a RAW file.

Aperture will automatically detect the type of camera that was used to shoot the image and will show the camera's name in the Camera field. Apple has profiled all cameras supported by Aperture and created RAW-conversion parameters for each camera. The Settings pop-up menu defaults to Apple, indicating that the Apple-defined RAW-conversion parameters are being used.

We'll explore the Boost slider in a later exercise. For now, we're going to focus on the other Fine Tuning sliders, which handle sharpening and noise reduction.

1.	If the image is not already set for 1.1 RAW conversion, set it now by selecting 1.1 from the small pop-up menu at the upper right of the RAW Fine Tuning controls group. As with any other sharpening tool, your goal with the Fine Tuning controls is to improve the sharpening in your image without accentuating the noise. This image has very soft edges, so we'll start with the Edges slider, which sharpens the edges in your image.
2.	Drag the Edges slider to the left to about 0.75.
3.	Slide the Intensity slider to about 0.72. Your image should appear noticeably sharper. Now take note of the noise. By default, the 1.1 RAW converter has its Auto Noise Compensation and Chroma Blur options selected.
4.	Deselect Auto Noise Compensation and Chroma Blur. You should see the image get noisier in the area under her neck. Note the bright-colored speckles in the shadow under her neck, as well as grainy noise patterns.
5.	Select the Chroma Blur control and drag its slider to around 6.8. Most of the colored noise patterns on the woman's neck should disappear. Chroma Blur looks for pixels that have a sudden change in color and then applies a slight blur to them to smear the color away.
6.	Select the Auto Noise Compensation checkbox. You should see a lot of bright red pixels beneath her arm disappear, and the grainy patterns in the shadow of her neck should become less obvious.

As with all sharpening and noise-reduction tools, you'll usually perform a balancing act with these sliders, as you try to sharpen your image without making the noise more visible. On some RAW images, you'll probably find that you can achieve all of the sharpening and noise reduction that you need with the Fine Tuning sliders. On others, you might need to also apply the normal sharpening and noise-reduction adjustments.

Adjusting Boost

Now let's look at another adjustment control in the RAW Fine Tuning controls group: Boost. As mentioned earlier, Aperture includes a set of camera profiles for all supported cameras. These profiles give Aperture specific details about each camera's imaging characteristics, and are used to determine what color and contrast adjustments should be automatically applied to the RAW file.

The Boost slider lets you control the degree to which this default adjustment is applied to your image.

By default, the Boost slider is set at full strength: your image appears with the full level of correction. As you drag the slider to the left, the correction is reduced.

The Boost slider is handy for times when you feel your images are a little too contrasty or a little too saturated.

1.	Press F to exit Full Screen mode and select boat raw in the Browser. We first need to perform an Exposure adjustment to set the highlights in the image properly.
2.	In the Adjustments Inspector, drag the Exposure slider to about 0.76. Watch the histogram to see when the image's highlights are no longer clipped.
3.	In the RAW Fine Tuning controls group, drag the Boost slider to 0.46. Your image should appear slightly less saturated, and you will probably see some brightening in the shadowy areas under the boat. As the contrast in the image is reduced, the shadows will brighten up a little bit. Overall, the image will appear a little more flat. In many cases, a flatter image will be more pleasing than an image with harsh contrast.