Chromatic Aberrations


Today’s Question: Upon reviewing a group of recently imported images into Lightroom 5, I noticed strong alternating blue and yellow bands across textured metal surfaces in 3 of my photos. Lightroom automatically removed the banding in 2 of the images within a few seconds of switching to the Develop Module. However, the third and most strongly banded image, containing a bank of escalator steps, remains unaffected. Any suggestions?

Tim’s Quick Answer: Your description certainly sounds like chromatic aberration. Presumably you have the “Remove Chromatic Aberration” checkbox turned on with your default settings in the Lens Corrections section of the right panel in Lightroom’s Develop module. However, this option doesn’t always provide a complete solution. You can, however, make use of the Defringe options below the “Remove Chromatic Aberration” checkbox on the Color tab of the Lens Corrections section to further improve the result.

More Detail: The type of visible artifacts you describe can be caused by a variety of factors, and fortunately can be resolved very effectively with the Lens Corrections adjustments available in Lightroom’s Develop module as well as Adobe Camera Raw, among a variety of other software tools that provide this correction option.

I find that in about half of the images that require a correction for this type of color fringing, the “Remove Chromatic Aberration” checkbox provides a good solution. In the other half of images that require this correction the Defringe controls provide enough control to resolve the color fringing.

There are two sets of controls for Defringe, allowing you to adjust the Amount (strength) of the correction and the range of color values to be corrected. The first set of sliders applies to magenta fringing in the image, and the second set applies to green fringing.

My approach for the Defringe sliders starts by zooming in on the area of the image where the color fringing is visible. Then increase the Amount slider significantly for the color correction that is needed (or the color that is closest to the problem color) to see if the fringing is corrected. If the color fringing is not completely removed with a large increase in the Amount control, you can expand the color range for the applicable Hue slider. Be careful not to increase the range too much, because doing so may cause the correction to blend into areas where you don’t want the color removed.

You can then reduce the value for the applicable Amount slider to a more appropriate level. By fine-tuning the specific range of colors being impacted and the strength of the adjustment for each color, you can generally produce a great result. In some cases there may be a minor amount of fringing left behind, but generally with a bit of careful attention to the slider values you can achieve a very good (and often excellent) improvement for the photo.