.Chromatic aberration occurs when the imaging system (such as a camera) places incorrect colors in at least some locations within the image. In conventional film cameras, this is usually caused by a lens defect. In digital cameras, a number of effects can contribute to chromatic aberration, including:
The camera's inherent lens aberration (which causes fuzziness at image edges); often more common with telephoto and zoom lenses.
The camera's auto-exposure (how it estimates the correct exposure setting), which can lead to sensor blooming.
The demosaicing process (where different colors are caught by different camera sensor elements and combined to make one pixel) taking place inside the camera.
To a much lesser extent, the postprocessing (artifact removal, noise removal, and sharpening) that takes place inside the camera.
In your own digital photos, you may notice chromatic aberrations in these types of situations:
The sky seen through tree branches or leaves
The edges of interior doors or windows where bright light is coming through
Night photos of fireworks or city lights
Photos of fluorescent light fixtures or bare light bulbs
Sun or light reflections on water
Reflections on chrome
The edges of backlit objects
Sunlit white shirts against a dark background
Photos taken with telephoto and zoom lenses may be more prone to contain chromatic aberrations due to the way digital cameras capture light rays far from the optical axis.
Here is an example that may help you better understand what chromatic aberration looks like.
Click here to see a photo of pine trees. Note the purplish hues in the indicated areas. Clearly, the actual tree does not have purplish branches, yet this is what the camera captured.
Click here to see how you would quickly designate the purplish hue for correction in the Chromatic Aberration Removal dialog.
Click here to see the corrected image.
Paint Shop Pro's Chromatic Aberration Removal filter can eliminate or reduce these types of color defects. Use of the filter is described below.
Choose Adjust > Photo Fix > Chromatic Aberration. The Chromatic Aberration Correction dialog opens.
Note: It's
critical in using this dialog that the left and right preview windows
are visible. Make sure the Show/Hide
Previews button is active (appears sunken) .
In most cases, you should zoom
to at least 200%. This simplifies targeting problem areas in the photo.
Use the dialog's Zoom In 
and Zoom Out 
buttons as needed.
In the left preview window, dragging
the cursor encloses a sampled area defining an area needing correction.
Use the Navigate button 
to pan the image and set a viewable image area in the left
preview window. Note the following points:
You can create a maximum of ten samples. If you've identified more than ten, apply the corrections and then restart the effect.
For each sample box, a corresponding "Sample n" (where n is 1 through 10) appears in the List of Samples area located in the center of the dialog. Each Sample listing has a color swatch to the left, indicating a color average for the sampled area.
Place the cursor over a sample handle to enlarge or reduce a sample.
To delete a sample, click it (or its corresponding Sample listing) and then click the Remove button in the bottom right of the dialog. You can also delete a sample box by dragging a corner onto its diagonally opposite corner and then releasing the mouse button when the corners meet.
To select a specific sample, click its corresponding "Sample n" entry in the List of Samples area.
The Range setting (located to the right of the List of Samples area) displays the color range of the active sample. The color box directly above the Range setting shows a visual representation of the range. You can increase or decrease the active sample's range value to affect the pixel range that will be corrected.
Mark the Show Differences check box to show which image areas will be affected. The affected areas will appear in the right preview window as white areas on black. The brighter (whiter) the area, the more degree of correction will be applied.
If Show Differences is marked,
click the Auto Proof 
or the Proof button
to preview the results on the image itself.
The Radius setting (located to the left of the List of Samples area) indicates the size of the sample's aberration. The default value is 10. Usually values in the range of 4 to 20 produce the most acceptable results. Values greater than 10 are useful on sampling areas enclosing sensor blooming aberrations. Values lower than 10 are useful when trying to remove 1 or 2-pixel aberrations caused by demosaicing, as well as when using the filter on images less than one megapixel. Generally, set the Radius to the smallest setting that will effectively remove the aberration.
Mark the Result on New Layer check box to automatically create a new raster layer (assuming you click OK to apply corrections) on which the corrected image will reside. This is a convenient way to protect your original, unedited image on its own layer. If you do not mark this check box, the corrections will be applied on the same layer as the original image.
Click OK to apply the corrections.
Be aware that you can limit the number of "false corrections" by making a selection and then applying this filter. You can also use this filter on separate image layers.