Chromatic Aberration and How to Fix It

There were times when I would take pictures and notice some purple or blue edges around my subjects. I didn’t have a clue what these were, much more how to get rid of them. When a friend pointed out that they were called ‘chromatic aberrations’, I got worried because it sounded serious like some sort of camera disease.

Chromatic aberration (commonly known as ‘purple fringing’ or ‘color fringing’) occurs when the lens fails to focus all the different wavelengths of light in a certain focal point.The result is a ‘fringe’ or edge of color, usually purple, blue, or red that appears on the margins of high contrast areas in the image. An example would be this crop of an onion photo. It shows an obvious blue fringe between the black background and the white outer onion layer.

You can buy specialty lenses or high end lenses to greatly decrease the possibility of getting this unattractive effect. However, these are also very expensive. There are different ways to get rid of chromatic aberrations in your final image without having to spend.

Choose a smaller aperture size – the effect is most noticeable at the edges of the lens. Therefore, a smaller lens opening reduces the appearance of the aberration. It may not remove it completely but at least it will make the fringes less visible.

Remove them in post processing – if you have any images that show chromatic aberration, you can still remove them in post processing. A quick fix in Photoshop would be to click on the hue/saturation adjustment, choose ‘magenta’ under ‘edit’, use the eyedropper to pick the purple fringe, then desaturate. The fringe will turn gray and it will be much less obvious. If you want to be meticulous, you can use the clone stamp tool to remove the aberration. There are other ways to remove its appearance in post processing such as masking or darkening the edges. Just go with whatever is easy and satisfactory for you.

Convert to black and white – Probably the quickest fix is to convert the entire image to black and white. This way you don’t have to deal with fixing the purple fringes at all. However, your image should look good in monochrome for you to go this route.

This entry was posted on Sunday, August 29th, 2010 at 9:00 am and is filed under Articles, Photography Basics, Photography Techniques. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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One response to “Chromatic Aberration and How to Fix It”

  1. If you shoot RAW files, you can also use the Chromatic Aberration sliders (Red/Cyan and Blue/Yellow) and the Defringe command in Adobe Camera RAW. Saves a lot of time!

    Even if you do not shoot RAW, it is possible to open JPEG and TIF files in ACR too.

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