Remove chromatic aberration
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.
Important: The Chromatic Aberration adjustment controls are available only for images using Aperture 3 image processing. For more information, see Reprocess photos from earlier versions of Aperture.
Remove purple fringing from an image
Select a photo.
If the Chromatic Aberration controls aren’t shown in the Adjustments inspector or the Adjustments pane of the Inspector HUD, choose Chromatic Aberration from the Add Adjustment pop-up menu, and specify the following settings:
To neutralize red or cyan fringing: Use the Red/Cyan parameter controls.
Adding cyan neutralizes red fringing, and adding red neutralizes cyan fringing.
To neutralize blue and yellow fringing: Use the Blue/Yellow parameter controls.
Adding yellow neutralizes blue fringing, and adding blue neutralizes yellow fringing.
You can also brush the Chromatic Aberration adjustment on specific areas of an image. For more information, see Apply brushed adjustments.