Working with the Sharpen and Edge Sharpen Controls

Aperture provides two sharpening adjustments that you can use to sharpen the detail in your image: Sharpen and Edge Sharpen.

Which Sharpening Adjustment Should You Use?

If you’ve already applied sharpening in a previous version of Aperture using the Sharpen adjustment controls, the Sharpen adjustment controls are still there so that your adjustments remain intact and unchanged. However, to do further sharpening on other images, it is recommended that you use the Edge Sharpen adjustment controls, which generally offer more precise control over how sharpening is applied. For more information, see Working with the Edge Sharpen Controls.

Working with the Edge Sharpen Controls

You use the Edge Sharpen controls when you want to sharpen the detail in your image. Images shot with digital image sensors are often a bit soft in focus because of the demosaic filter applied by the camera’s processor. The Edge Sharpen controls adjust the luminance values in the image, increasing the contrast between light and dark pixels that touch, creating an “edge.” Increasing the contrast between these neighboring light and dark pixels gives the image a crisper, or sharper, appearance. You also use the Edge Sharpen controls when you make noise-reduction adjustments, so that the image retains detail and crisp edges that might otherwise be obscured by the effect of the noise-reduction adjustment.

Figure. Image before and after an Edge Sharpen adjustment.

Important: The Edge Sharpen controls are not designed to correct images that were shot out of focus. They are designed to help mitigate the effects of the camera’s demosaic filter, as well as maintain image detail when noise-reduction adjustments are applied. Edge Sharpen adjustments can also compensate for the softening that occurs with some printing processes.

To sharpen an image using the Edge Sharpen controls
  1. Select an image.

  2. If the Edge Sharpen controls are not shown in the Adjustments inspector or the Adjustments pane of the Inspector HUD, choose Edge Sharpen from the Adjustments pop-up menu (or press Control-S).

  3. Sharpen the image by doing one of the following:

    • Drag the Intensity slider to the right to increase the amount of sharpening applied to the image, and drag the slider back to the left to reduce the amount of sharpening.

    • Click the left or right arrow in the Intensity value slider to adjust the sharpening by 5 percent increments, or drag in the value field. The left arrow decreases the sharpening effect on the image, and the right arrow increases it.

    • Double-click the number in the Intensity value slider, then enter a value from 0.0 to 1.0 and press Return.

      Figure. Intensity controls in the Edge Sharpen area of the Adjustments inspector.

    A value of 0.0 applies no sharpening adjustment to the image. A value greater than 0.0 increases the sharpening adjustment applied to the image.

  4. Adjust the threshold for determining which pixels are edges and which ones are not by doing one of the following:

    • Drag the Edges slider to the right to increase the area over which the sharpening effect is applied, and drag the Edges slider back to the left to reduce it.

    • Click the left or right arrow in the Edges value slider to adjust the area over which the sharpening effect is applied by 5 percent increments, or drag in the value field.

    • Double-click the number in the Edges value slider, then enter a value from 0.0 to 1.0 and press Return.

      Figure. Edges controls in the Edge Sharpen area of the Adjustments inspector.

    A value of 0.0 applies no sharpening adjustment to the image. A value greater than 0.0 increases the number of pixels that qualify as edges.

    Note: If you observe digital noise beginning to increase in flat areas of the image (areas with little or no contrast), decrease the Edges parameter setting.

  5. For maximum accuracy, the Edge Sharpen adjustment sharpens the image in three passes that appear to occur simultaneously—an initial sharpening pass, where a majority of the sharpening occurs, followed by two subsequent sharpening passes. These subsequent passes are called falloff. Adjust the amount of sharpening applied in the subsequent sharpening passes by doing one of the following:

    • Drag the Falloff slider to the right to increase the percentage of the original sharpening that’s applied during the subsequent sharpening passes, and drag the slider back to the left to reduce it.

    • Click the left or right arrow in the Falloff value slider to adjust the falloff percentage by 5 percent increments, or drag in the value field.

    • Double-click the number in the Falloff value slider, then enter a value from 0.0 to 1.0 and press Return.

      Figure. Falloff controls in the Edge Sharpen area of the Adjustments inspector.

The falloff percentage is applied proportionally to the second and third sharpening passes. For example, if 0.69 (69 percent) is set as the Falloff parameter value, 69 percent of the original amount of sharpening is applied during the second sharpening pass, and 69 percent of the amount of sharpening from the second sharpening pass is applied during the third sharpening pass. In other words, only 47.6 percent of the amount of the original sharpening is applied during the third sharpening pass.

You can also brush the Edge Sharpen adjustment on selected parts of an image. For more information, see Making Brushed Adjustments.

Understanding the Edge Sharpen Workflow

The Edge Sharpen adjustment in Aperture is a professional tool that’s used to sharpen photos. Using the Edge Sharpen adjustment controls in conjunction with the following workflow makes it easy to achieve professional results.

To sharpen an image
  1. In the Edge Sharpen area of the Adjustments inspector or the Adjustments pane of the Inspector HUD, set the Intensity slider to the maximum value to see the effect of the operation.

  2. Adjust the Edges slider so you can see which parts of the image are being sharpened. If possible, adjust the Edges slider so that edges are sharpened, but noise and texture in the image are not affected.

  3. Adjust the Falloff slider so that the edge sizes you want sharpened the most are accentuated.

  4. Decrease the Intensity parameter value until the sharpening effect is appropriately subtle. Values below 0.5 usually work best.

Working with the Sharpen Controls

You use the Sharpen adjustment controls when you need to modify Sharpen adjustment parameter settings that were applied to an image in a previous version of Aperture.

To sharpen an image using the Sharpen controls
  1. Select an image.

  2. If the Sharpen controls are not shown in the Adjustments inspector or the Adjustments pane of the Inspector HUD, choose Sharpen from the Adjustments pop-up menu.

  3. Sharpen the image by doing one of the following:

    • By default, the Intensity slider is set to 0.5. Drag the Intensity slider to the right to increase the amount of sharpening applied to the image, and drag the slider back to the left to reduce the amount of sharpening.

    • Click the left or right arrow in the Intensity value slider to adjust the sharpening by 5 percent increments, or drag in the value field.

      The left arrow decreases the sharpening effect on the image, and the right arrow increases it.

    • Double-click the number in the Intensity value slider, then enter a value from 0.0 to 1.0 and press Return.

      Figure. Controls in the Sharpen area of the Adjustments inspector.

    A value of 0.0 applies no sharpening adjustment to the image. A value greater than 0.0 increases the sharpening adjustment to the image.

  4. Adjust the area over which the sharpening adjustment is applied (the distance, in pixels, that Aperture goes from each pixel to evaluate sharpness) by doing one of the following:

    • By default, the Radius slider is set to 1.0 pixels. Drag the Radius slider to the right to increase the area over which the sharpening effect is applied, and drag the Radius slider back to the left to reduce it.

    • Click the left or right arrow in the Radius value slider to adjust the Radius pixel distance by 5 percent increments, or drag in the value field.

    • Double-click the number in the Radius value slider, then enter a value from 0.0 to 20.0 and press Return.

    A value of 0.0 applies no sharpening adjustment to the image. A value greater than 0.0 increases the area over which the sharpening adjustment is applied.

As you change the parameter values, the image is updated to display the sharpening effect.

You can also brush the Sharpen adjustment on selected parts of an image. For more information, see Making Brushed Adjustments.