Attention to detail

Inspired by Lucy and Jonesy's comments, I purchased a copy of Lightroom and have begun working through Adobe's training guide.  Within the first hour I have been amazed and delighted to discover the many wonderful ways this software enables photographers.  What has prompted me to make this post is a small part of one exercise that impressed me with it's attention to detail, a thing so small I wouldn't have noticed it if the guide writer hadn't drawn my attention to it.

Here are before and after photos.  Can you see what has been changed?  Click on the photos to see enlarged views.  

The answer is below in black text. Click and drag to select and reveal the answer.

Before

After

From the guide:

Your adjustments have brightened and intensified
our underexposed lesson image. Unfortunately they
have also intensified a digital artefact known as
chromatic aberration, which results in colored
fringes around pictured objects, usually most noticeable
near the edges of a photo where the lens has
been unable to accurately focus the different wavelengths
of incoming light on the sensor.

8 Scroll down in the right panel group and expand
the Lens Corrections panel; then, select the
Profile mode in the picker at the top of the panel
and click the check-box to activate the Remove
Chromatic Aberration option. 

The aberration is to be found on the right side of the background spire.  Before adjustment, it has a thin outline of red, which Lightroom mostly removes (but is still somewhat visible at higher magnifications). 

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