Sharpening


All digital cameras blur their images slightly (you'll find out why in the next chapter). If you're shooting in JPEG mode, your camera may apply some sharpening to try to compensate for the blur. If you're shooting in raw mode, or if your camera didn't apply enough sharpening, or if you're shooting slightly out of focus, then you may need to apply some sharpening to your image.

Before exploring sharpening, you should keep this point in mind: sharpening isn't real; no image editor can actually sharpen the focus in an image. Therefore, it's important to try to shoot images that are sharp and in focus.

"Sharpening" filters work by trying to make high-contrast lines in your image more acute. Because a high-contrast line is usually an edge, this change in accutance can make your image appear sharper.

The sharpening filter in Aperture works by searching for an area of sudden contrast change: an edge. When it finds one, it brightens the pixels along the bright side of the edge and darkens the pixels along the dark side of the edge. This process serves to make the edge more prominent, and so the image appears sharper (Figure 5.60).

Figure 5.60. Aperture's Sharpen adjustment was applied to the top image to create the bottom one. Using Sharpen, you can eliminate a fair amount of softness in your images.


To add a Sharpen adjustment to your image, select Sharpen from the + menu in the upper-right corner of the Adjustments panel. The Sharpness adjustment (Figure 5.61) provides two controls.

Figure 5.61. The Sharpen adjustment provides two parameters.


Intensity specifies how much the pixels surrounding an edge are lightened or darkened.

Radius lets you control the width of the area that Aperture analyzes when looking for an edge.

When configuring the Sharpness parameters, you'll want to view your image at 100 percent, to accurately determine how much sharpening is being applied. If you're viewing at a smaller size, some sharpening effects may be not be visible, which can lead you to over-sharpen. Press the Z key to zoom to 100 percent.

If the default settings don't provide enough sharpening, start by leaving the Radius slider at its default value of 1. Try increasing the value of the Intensity slider to see if your image sharpens up enough. If it doesn't, then place the Intensity slider in the middle of its range and try increasing the radius. Work with the two sliders to find a balance.

Beware of oversharpening! Although it may seem like sharper is inherently better, remember that the Sharpen filter is not actually making your image sharper. It's creating an illusion of sharpness by drawing halos around the edges in your image. If you sharpen too much, your image will become garish (Figure 5.62).

Figure 5.62. It is possible to over-sharpen an image, causing annoying artifacts and a loss of detail.


Tip

Sharpening often results in slightly increased contrast in your image. It's best to apply sharpening at the end of your workflow. If you then see an increase in contrast, either reduce the amount of sharpening or use Aperture's tonal controls to compensate.





Real World(c) Aperture
Real World Aperture
ISBN: 0321441931
EAN: 2147483647
Year: 2007
Pages: 106
Authors: Ben Long

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