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interface haven’t noticeably improved in the

current release.

RawTherapee

This freeware RAW converter has, over the

years, developed into a comprehensive RAW

conversion and editing package with a feature

list that is just as long as that of the

commercial competition (see our article on

RawTherapee in Issue 7 of c’t Digital

Photography). The program includes a

number of tools for correcting chromatic

aberrations – the Detail tab includes the

Defringe filter, the Lens/Geometry tab

includes the C/A Correction tool and the RAW

tab has its own Chromatic Aberrations tool

that offers manual and automatic error

correction.

RawTherapeewas able to open all of our

test images, and the automatic correction

tool produced great results (although still not

quite up to Nikon standards) for our lateral

aberration test. Manual corrections are quite

laborious because the preview image

refreshes very slowly after each slider

adjustment. As recommended by the

software’s authors, we used a dual-core 64-bit

system with plenty of RAM for our test, but

we still spent quite a lot of time waiting.

There is no before/after view, which

makes comparing images difficult, and

‘features’ like the heavily pixelated view

when shifting a detail in the preview window

often reminded us of the program’s open

source heritage. This isn’t particularly nice to

look at but does make recognizing

erroneously colored pixels quite simple.

In general, the program’s automatic

correction tool produced passable results with

little effort for everyday subjects like our

skyscraper. It is safe to say that the differences

in quality produced by all of the programs we

tested are not particularly significant at

normal viewing distances. Where

RawTherapeecouldn’t really compete was

correcting axial errors, and we weren’t able to

produce any visible improvements using any

of the built-in tools.

Neither the automatic nor the manual

Chromatic Aberration tool worked at all for

JPEG images, although the Defringe and C/A

Correction tools both produced usable results

after a bit of manual tweaking (automatic

correction only works for RAW images). Care

is required when correcting chromatic

aberrations in RawTherapee. We often found

that by the time we had perfected a

correction in one part of an image, new

artifacts had appeared elsewhere. Just as in

RAW mode, we weren’t able to produce any

convincing JPEG results for our axial errors,

and we searched in vain for settings that

genuinely improved our target and sample

images.

RawTherapeeis fine for correcting lateral

errors in JPEG and RAW images, although its

handling in RAW mode is much more

user-friendly. If you don’t want to correct any

significant axial errors and you don’t mind a

bit of a fight with a somewhat clunky

interface, RawTherapeeoffers a no-frills RAW

converter that is easy to use, and its freeware

status makes it a real alternative to the

commercial competition, especially for

occasional users. (keh) c

RawTherapee‘s automatic filter reduced

the effect of the error, although the

magnified view shows that the tool still

has its limits

The unfiltered image shows very obvious

lateral aberrations

Setting the correction values manually

enabled us to completely remove the

fringing effects

RawTherapeeincludes

automatic and manual

chromatic aberration

correction tools

Chromatic Aberrations | Software Test