Learn how to get rid of a special variety of color distortion called color fringing that’s at work inside your digital photographs. Color fringing falls into two color ranges—purple and green—which are color complements, falling on opposite sides of the color wheel. In this week’s Deke’s Techniques, Adobe guru Deke McClelland shows you how to identify and remove color fringing inside Camera Raw, and ensure that you get accurate color corrections.
Note that these instructions work best with Camera Raw 7, which ships with Photoshop CS6. If you’re working in an older version of the program, check out the videos at the end of this tutorial.
1. Start with the exercise file available from the lynda.com library, or use a RAW, TIFF, or JPEG file of your own.
2. Open the file inside Camera Raw. The recommended workflow is to start in Adobe Bridge, locate and right-click the image, and choose Open in Camera Raw.
3. For a basic adjustment, increase the Exposure value to 1.25, Contrast to +50, and Highlights to 25. Normally this might be sufficient, but in order to examine the fringing better, you should also raise Vibrance and Saturation to +100, the maximum value for these fields.
4. Switch to the Lens Correction panel, turn on Enable Lens Profile Corrections, and zoom way into the image (200% or more) to view the chromatic aberration.
Color fringing, or chromatic aberration, occurs as light makes its way through the camera lens and hits the image sensor. You’ll get more distortion with wide-angle shots, like Deke’s example, and telephoto images.
5. A lot of the fringing can be removed in one simple step. Switch to the Color tab inside the Lens Correction panel and check Remove Chromatic Aberration.
This check box also appears in Camera Raw 6. However, you may notice that it doesn’t totally eliminate the problem. That solution can be found in the Defringe slider, which was just introduced in Camera Raw 7.
6. The Purple Hue and Green Hue sliders tell Camera Raw what constitutes green and purple; the Amount sliders control the defringing itself. Note if you expand the hues too far, you can create jagged transition and gaps in your image.
In this case, Deke uses
• Purple Amount of 10
• Purple Hue of 10/70
• Green Amount of 10
• Green Hue of 40/80
If you’d like to restore the default Hues, just remember Purple is 30/70 and Green is 40/60.
7. Now return to the Basic panel to restore normal Vibrance and Saturation values, 50 and 20 respectively in the case of our sign.
8. To deal with any residual noise in your image, go to the Detail panel and dial in a Luminance of 25.
9. To recreate the vignetting we lost when we turned on Remove Chromatic Aberration, go to the Effects panel and take the Post Crop Vignetting Amount down to -35.
10. Finally, press the Shift key and click Open Object to open the image as a Smart Object in Photoshop, where you can continue making nondestructive edits if you so choose.
And that’s how to precisely correct the color fringing associated with chromatic aberration. Stay tuned next week when Deke raises the warning level of his color-corrected sign to “extra scary” with some intricate shape layers in Photoshop.
Interested in more?
• Start your 7-day free trial to lynda.com today
• Eliminating edge fringing from Photoshop CS5 One-on-One: Fundamentals
• Vignette and chromatic aberrations from Photoshop CS5 One-on-One: Advanced
• The entire Deke’s Techniques collection
• Photoshop CS6 One-on-One: Intermediate
Adobe and Photoshop are registered trademarks of Adobe Systems Incorporated.