RawTherapee and CA correction?

barry13

Mu-43.com Editor
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Mar 7, 2014
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Barry
Hi,

I've got a couple of RAW files from my E-M1 and 12-40mm lens that have some Chromatic Aberration.
I'm trying to figure out how to fix them in RawThreapee.

The JPEGs from the camera are OK (wrt CA), and the Oly Viewer is able to correct the CA, but I don't like its interface and want to learn how to use RT fully.

RT can load LCP Lens Correction Profile files, but I've done some searching and afaict they don't seem to exist, other than that they are supposedly 'built-in' to the RAW files. However RT will only let you choose the auto CA correction setting if you have an LCP file loaded.

So,
1. are there any LCP files available for our lenses, or some way to get RT (current version, 4.0.12.60) to recognize the embedded profiles?

2. without an LCP file, what is the best way to try to remove CA in RawTherapee or Gimp or similar?

Example, 100% crop from RAW:
Subscribe to see EXIF info for this image (if available)


This part of the image is somewhat over exposed, fwiw.
Also, the CA isn't quite this bad before hitting 'Auto Levels', etc. in RT but it's still pretty bad.

Thanks,
Barry
 
Last edited:

cireyay

Mu-43 Rookie
Joined
Dec 31, 2013
Messages
23
Hi Barry,

I'm currently using RT 4.1.1 and it does apply CA correction automatically when you double click on a RAW img and the PP interface shows up. However I don't recall it doing it in previous versions. Hence you could update/download the latest version and give it a shot?

I'm using a pana GX1 by the way, not sure if that will make a difference
 

barry13

Mu-43.com Editor
Joined
Mar 7, 2014
Messages
9,210
Location
Southern California
Real Name
Barry
Hi, I had searched to see if there was a new version, and Google was linked to an old download page...

So, I'm now running 4.1.49 on Windows but it's still not doing CA correction...
Under "Lens/Geometry" the 'Auto-Fill' setting is checked, but further down, under "Lens Correction Profile", there is no file selected and the distortion, vignetting, and CA correction checkboxes are greyed out.

Can you load my raw file (linked above) and try it in yours?
Zoom in on the motorcycle, and look for the CA on the chrome bars and letters.

Are you on a Windows PC or Mac or Linux?
Which lens are you using?

Thanks!
Barry
 

Brian Beezley

Mu-43 Hall of Famer
Joined
Jan 27, 2012
Messages
2,062
Location
San Marcos, California
Barry, try Defringe. Its default parameter values cleaned up the red/purple on the motorcycle when using Neutral. When using Auto Levels, Highlight compression seems to make the red/purple worse. Try adjusting it and the associated threshold.

Brian
 
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