cannot be perfect. A lens may not be perfect either. These
may cause color noise — or by its beautiful name of chromatic
aberration — among others. You will most often spot them
on the edge and in the corner of photos in the form of purple-green
or blue-yellow color stripes. In size it can vary from tolerable
to absolutely disturbing.
This problem is quite conspicuous on the 100% magnification
of the picture detail above, but if it’s not big enough,
we have put an even bigger version to the left. It’s a piece
of cake to remove these from RAW images if you know what
to use in Lightroom.
Where is it hiding?
use Develop section and within that visit
Details part in the setting panel on the
right. Chromatic Aberration window is here
with a few sliders and a small menu.
The first thing to do is to identify the color of the aberration
in the photo. In our case it’s a purple-green discoloration,
visible especially at the edge of the areas with big contrast
difference. Therefore we begin with Red/Cyan
you raise Red/Cyan slider value, you will
get an even stronger color distortion, so we have to decrease
it carefully, until the noise is removed. You may want to
use a 100% or even higher zoom value to be able to observe
We decreased Red/Cyan value gradually —
in grades of five — and arrived at an acceptable
result with the value of -25. But, as you
can see above, there’s a little blue-yellow noise left.
remove the weak blue-yellow aberration, we used Blue/Yellow
slider of course. This time we shifted it in the positive
direction. A value of +10 proved to be sufficient to remove
almost all of the discoloration.
Alongside the edges
versions of purple color noise, called fringe, can be removed
with the help of Defringe menu under the
sliders. This menu comes handy after we have finished modifications
on the sliders and wish to further refine the result. There
is some purple discoloration alongside some of the edges
still, which can be removed completely by selecting All
Edges menu. This menu can help decrease the slight
purple color stripes on the dark and light side of edges.
Highlight Edges will remove noise from
the light parts of edges. Slight color aberration will usually
appear on light parts.
Free of color noise
left side shows the original state with the quite conspicuous
purple-green color noise, while the right side shows the
result of our brief actions, practically free of color noise.
Adobe Lightroom Tutorials
Photoshop Lightroom - Noise filtering
Photoshop Lightroom 3 - Noise filter vs noise filter
Photoshop Lightroom - Selective image editing
Adobe Lightroom Tutorials