Working with the Chromatic Aberration Controls

When you want to fix chromatic aberration, also known as purple fringing, you use the Chromatic Aberration adjustment controls. For example, if your image has a ghost image in high-contrast boundary areas, you use the Chromatic Aberration adjustment controls to neutralize the color fringing. Chromatic aberration can be caused by a poorly designed lens that fails to focus light at the correct point on the focal plane when the lens is set at different focal lengths. Certain types of light sources can also cause chromatic aberration.

Figure. Image before and after a Chromatic Aberration adjustment.

Important: The Chromatic Aberration adjustment controls are available only for images using Aperture 3 image processing. For more information about reprocessing your images, see Reprocessing Images from Previous Versions of Aperture.

To remove chromatic aberration from an image
  1. Select an image.

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

  3. If your image exhibits red or cyan fringing, neutralize it by doing one of the following:

    • Drag the Red/Cyan slider to the right to add cyan, neutralizing the red fringing, or drag the slider to the left to add red, neutralizing the cyan fringing.

    • Click the left or right arrow in the Red/Cyan value slider, or drag in the value field.

    • Double-click the number in the Red/Cyan value slider, then enter a value from –5.0 to 5.0 and press Return.

      Figure. Red/Cyan controls in the Chromatic Aberration area of the Adjustments inspector.
  4. If your image exhibits blue and yellow fringing, neutralize it by doing one of the following:

    • Drag the Blue/Yellow slider to the right to add yellow, neutralizing the blue fringing, or drag the slider to the left to add blue, neutralizing the yellow fringing.

    • Click the left or right arrow in the Blue/Yellow value slider, or drag in the value field.

    • Double-click the number in the Blue/Yellow value slider, then enter a value from –5.0 to 5.0 and press Return.

      Figure. Blue/Yellow controls in the Chromatic Aberration area of the Adjustments inspector.

The chromatic aberration is removed from the image.

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