Street Photography Magazine

Chromatic Aberrations | Software Test

We checked out a range of image

viewers and RAW converters, from

ACDSee to Lightroom and

RawTherapee, to see just how useful

their built-in filters are for combatting

chromatic aberrations.

For our lateral aberration test, we used a

black, red and white checkerboard target that

made it relatively easy to observe the increase

in fringing toward the edge of the frame. For

the axial aberration test, we used a photo of

a grid pattern taken at an angle that caused

strong color casts in front of and behind the

plane of focus.

Chromatic aberrations in images of

homogeneous patterns look very different

from the ones that occur in everyday subjects,

so we tested each program (in RAW and JPEG

formats) on four selected test photos too.

While comparing our results, we noticed

that the colors in our RAW samples varied

quite strongly, so we ended up comparing the

effect of the filters themselves rather than

overall image quality. In other words, we

observed how the program behaved with the

filter switched on and off. For the JPEG test,

we converted all of our RAW source images

using RawTherapee.

Overall, our test revealed that lateral

aberrations can be effectively removed using

automatic tools and an appropriate lens

profile. Axial aberrations are much more

difficult to correct. Many programs don’t have

built-in tools for combating this type of error

and we didn’t find any really effective

automatic filters. We simply couldn’t

eliminate our focus-dependent color casts.

Some of the better test programs managed

to suppress isolated color patches and purple

fringing to a tolerable degree.

Filters that are capable of removing

blue/yellow fringes from out-of-focus areas in

an irregularly shaped subject are few and far

between. This is an important feature for

photographers who use long telephoto lenses

at wide apertures – a setup that is prone to

producing artifacts, even if the lens carries a

Leica or Zeiss label.

ACDSee Pro 4

Since the release of version 4, the ACDSee Pro

Detail menu contains the Chromatic

Aberration Correction tool, which has sliders

for correcting red/cyan and blue/yellow

errors. The Detail menu also contains the

Defringe tool.

The chromatic aberration tool worked well

on the lateral errors in our RAW files, and

produced visible improvements. But take care:

if you remove fringes at the top edge of the

frame, you need to make sure that they have

been effectively removed from the bottom

edge as well. This aspect of theACDSeetool’s

functionality is slightly temperamental due to

its lack of lens profile support.

There is no before/after view, but the

original image can be displayed quickly and

easily using a single mouse click. Nikon’s

Capture NX 2, for example, is much more

sluggish in this respect.

We were unable to produce any

improvement in our axial aberration test

image and the program had trouble with the

high-contrast edges in our portrait shot too.

Our attempts to remove blue fringing

produced new halo-like double images, which

wasn’t the effect we were looking for!

On the other hand, the program scored

well on the purple fringing in our dolphin

image. The Defringe tool effectively

suppressed the obvious pink fireworks in the

water, although the tool’s limits are still

obvious in the 100% view. The tool requires

you to juggle three separate sliders, and there

is no single setting that can effectively remove

irregular fringing in a single subject.

Basically, the tool works very well if the

fringes you want to remove are all the same

color and you are not too critical of the

results. The Defringe tool reliably removed

the color cast in our tree image, although – as

with Capture NX 2– the color of the sky

suffered a little as a result. Our JPEG tests

caused no surprises, and the results were very

similar to those produced by our RAW run.

To conclude, the ACDSee tool is great for

removing lateral aberrations, but the lack of

a batch processing tool makes it less practical

for use with multiple images. The Defringe

tool is fine for removing single-color fringing

of consistent strength. ACDSeedoes not

currently offer any usable options for

removing variable axial aberrations.

Apple Aperture

Apple’s own RAW converter started with a

bang but hasn’t managed to keep up with the

competition since. It still doesn’t provide lens

profile support and it supports only a limited

number of camera models. On the positive

side Aperture’s Chromatic Aberration tool

includes features that are superior to those

offered by much of the competition.

The bad news is that you can only apply

corrections manually using the Red/Cyan and

Blue/Yellow sliders, and the only way to

compare before/after versions of an image is

to use a working copy of your image as a

Computer-based

Chromatic Aberration Filters

OUR TEST PROGRAMS

Manufacturer Program URL Version tested Win Mac Linux Price (US$)

ACD Systems ACDSee Pro 4 de.acdsee.com 4.0 yes yes no 74.99

Adobe Lightroom 3 http://www.adobe.com 3.5 yes yes no 299.99

Apple Aperture http://www.apple.com 3.2.1 no yes no 159.95

DxO DxO Optics Pro http://www.dxo.com 6.6.0.173 yes yes no 169.00

Nikon Capture NX2 http://www.nikon.com 2.2.8 yes yes no 179.95

Phase One Capture One http://www.phaseone.com 6.3.2 yes yes no 59.99-179.99

RawTherapee Team RawTherapee http://www.rawtherapee.com 4.0.4.2 yes yes yes free

Our test images and their

source files are included on

this issue’s free DVD.

You can use them to perform

the same tests as we did on

your computer at home and decide

for yourself which are the best tools

for your situation.

Free Test Images

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