Adobe Photoshop Lightroom 2

While it is usually best to try and avoid situations that you know may be problematic there are times where you really want to take the shot and take care of the problems later.

When evaluating your photos you are not likely to see the purple fringing in Fit Screen view. You need to zoom in to at least 1:1 view to see if there is a problem that needs fixing.

In this example the fringe areas are most visible along the dark edges of the tree branches. Let’s go through the steps I followed for reducing the fringe in this image. One thing to note is that you want to perform this correction after you have made your basic white balance and exposure adjustments.

Step 1.

Expand the Detail panel.

Under the Sharpening and Noise Reduction controls you will find the Chromatic Aberration sliders—the Red/Cyan and the Blue/Yellow.

As the nickname “purple fringe” suggests the most common color fringe we see is a combination of red and blue. By adjusting each slider we are expanding or contracting the red or the blue channel (respectively) in relation to the other two, which in turn reduces the visibility of the color fringe.

Step 2.

Zoom to at least 1:1 view.

There are two ways to do this. You can either zoom the entire image to 1:1, which is the most effective, or use the zoom window in the Detail panel, which can be very helpful when you want to keep the main image zoomed out to Fit view to see the entire image while you work.

While working with the zoom window you can click and drag on the image inside the zoom window to examine different areas of the photo, or click the crosshair next to the zoom window and click on an area of the photo itself to zoom in on that area. You can right-click on the zoom window and choose between 1:1 or 2:1 zoom level.

When making chromatic aberration adjustments I find a zoom level of 2:1 to be more helpful.

Step 3.

Adjust each slider in turn to find the optimal result.

This is a visual process, and you may need to go back and forth a bit to find the sweet spot. I start with the Blue/Yellow slider as that is often going to have the greatest effect, then tweak the Red/Cyan as needed.

Step 4.

Fine tune with the Defringe adjustment.

This is a subtle adjustment that can sometimes improve upon your manual adjustment. As you can see in the previous figure I couldn’t completely remove the fringe with the sliders alone. Setting Defringe to All Edges did make an improvement.

At 1:1 view the visibility of the fringing is greatly diminished and possibly even acceptable depending upon the output. One last technique I will use for really problem fringing is to expand the HSL panel, set to Saturation, and click on the Target Adjustment Tool. Then place the cursor over a remaining color fringe and drag down slightly to desaturate a small amount. Just keep in mind that this will affect the selected color everywhere in the image, not just the point where you are clicking, so depending upon the colors in the image this may not be desirable in all cases.

Here is a before and after showing the cumulative effects of the sliders, defringe and a targeted desaturation of the fringe area.