How to edit/avoid Chromatic Aberration edges?
/forum/topic/1179214/0



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

I am having trouble avoiding getting white lines around my images after editing them. I am using lightroom with plugins like NIK. I correct lens profile & use lightroom to remove any CA but after editing images either just in LR or through a plugin I get them.

I have tried no sharpening, lowering contrast levels, no clarity etc. What enhances the CA edges?

Thanks,


Mike



Cphoto1954
Registered: Dec 17, 2008
Total Posts: 668
Country: United States

LR 4.3 should be able to remove every single bit of it for you under the CA custom settings.



Eyeball
Registered: Jan 11, 2005
Total Posts: 3784
Country: Mexico

An example pic (before and after would be even better) and a more complete explanation of your workflow for a particular image would be very helpful. "white lines" doesn't exactly sound like CA unless it is the result of severe fringing that has already been corrected by LR.

As Cphoto says, the latest version of LR usually does a pretty remarkable job.



hugowolf
Registered: Nov 11, 2011
Total Posts: 591
Country: United States

MikeW wrote:
I am having trouble avoiding getting white lines around my images after editing them. I am using lightroom with plugins like NIK. I correct lens profile & use lightroom to remove any CA but after editing images either just in LR or through a plugin I get them.

I have tried no sharpening, lowering contrast levels, no clarity etc. What enhances the CA edges?
Mike

The only way I can see you getting a halo, is if you are starting with over sharpenned jpgs. If you are working from raw and doing lens corrections first, then LR should not create halos.

Brian A



abqnmusa
Registered: May 11, 2006
Total Posts: 2085
Country: United States

Nik plugins can leave odd artifacts in images. I abandoned using them



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

I think rather than CA it is the contrast which when sharpened becomes more obvious. I don't have access to a more realistic edit (done for the missus, she likes the look) but this image is an example:



A crop from an unedited version:



You can see on the angled timber the white line, once sharpened this is much more evident. This isn't from the focus point, it is the same wherever. But they are raw files, not jpgs.



Eyeball
Registered: Jan 11, 2005
Total Posts: 3784
Country: Mexico

What were your LR settings for the "unedited" raw file - particularly Clarity, Sharpening, and any CA corrections you may have used?



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

just a white balance fix, crop, save as jpg.



redcrown
Registered: Sep 10, 2004
Total Posts: 778
Country: United States

Can't tell much from you posted samples, but as you suspect, I think your problem is not CA related but is instead a result of sharpening. Depending on how you sharpen, it's common to get halos around high contrast edges. Some sharpening techniques, especially the third party plugins help avoid that.

Unfortunately, I don't think there is any way to control halos in Lightroom. But if you have Photoshop, here is one common technique.

1. Sharpen your image as desired with the tool of choice (Lightroom, USM, Smart Sharpen, etc.). Ignore halos, and don't be afraid to be aggressive.
2. Put that sharpened image in a layer on top of a copy of the unsharpened image.

3. Enlarge to 100% or more and focus on some halos.
4. Double-click on the sharpened layer to access the blending options.
5. In the "Blend If/This Layer" section, drag the right triangle to the left until the halos disappear. You can also alt-click on the triangle to split it into two different control points.

Toggle the sharpened layer on and off to see the difference, and re-adjust the Blend If controls as desired.



Eyeball
Registered: Jan 11, 2005
Total Posts: 3784
Country: Mexico

MikeW wrote:
just a white balance fix, crop, save as jpg.


Are you really, really sure that your LR defaults are not set to give you some basic level of sharpening? These really look like sharpening halos. They are not horrible and I am doubtful they would even appear in a print from the "unedited" version but they are probably being emphasized/amplified with the Nik effects.

If you could provide a link to a raw file, I would be glad to check the file for you.

Regarding your the processed version you posted, I don't really see any evidence of the "white lines" or halos at the size you have posted. Maybe a tiny bit in the snow at the bottom right-hand corner and along the log that you cropped out for the unedited version but I'm not even sure about that. I certainly don't see any "sparklies" or straw-like effects that are typical indicators of over-sharpening.

Nice image, by the way. The special processing works for the image IMO.



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

thanks for the info redcrown, I will give it a go & check out lightroom, I have a fresh install & haven't changed any defaults.

Eyeball, it is hard to see on the full image, you have to zoom in to see it. I had an image I printed 20x36 with deadwood & it is horrible, same situation

I can try to upload the raw today.

Thanks,


Mike



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

never used this site for uploads, hope it works ok:

http://www.2shared.com/file/nIyL2uon/MIK_7556.html



Eyeball
Registered: Jan 11, 2005
Total Posts: 3784
Country: Mexico

My antivirus blocks that site as potentially dangerous and I'm reluctant to use it.

Do you use DropBox by any chance? You could put it in your public folder there if you have one.

A trial with yousendit would be another alternative. It is a pretty well-known, popular site for this kind of thing.



redcrown
Registered: Sep 10, 2004
Total Posts: 778
Country: United States

Mike, that raw file is in fine shape. The amount of CA is very little. I have to view at 300% to even see it, and then the base CA removal in ACR cleans it up perfectly.

The shadows are a little dark under the Adobe Standard profile, but if you shift to Camera Neutral and add a little shadow recovery they open up nicely.

I don't know how you are shapening, but I was able to sharpening this image quite aggressively without generating any halos. I use Topaz Detail for most of my sharpening now, but even if I use Photoshop USM to sharpen I can go quite a way before generating halos. With a USM amount of 500 (the max) and a radius 0.3 I see no halos.

I have to increase the USM radius to 1.0 to get faint halos, and even then the "Blend If" move I described above removes them. However, while that level of sharpening looks good to me on the foreground posts, it destroys the trees. IMO, the trees need far less, or zero sharpening.



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

http://dl.dropbox.com/u/20029887/MIK_7556.NEF

hopefully thats better. We use Dropbox for work, this is in pub folder though.

Mike



hugowolf
Registered: Nov 11, 2011
Total Posts: 591
Country: United States

Raw looks fine in LR with the default sharpening: Amount: 25, Radius: 1, Detail: 25;
Noise reduction color 25, detail 50.

Are you not doing some output sharpening in the export dialog?



Eyeball
Registered: Jan 11, 2005
Total Posts: 3784
Country: Mexico

File looks fine to me, too. No halos.

I suspect that you were using default sharpening in LR, which makes the halos very slightly visible at 100%. You may also be doing output sharpening in Export as Hugo suggests.

Redcrown's Blend-if suggestion is a good one, particularly for extreme white/black edges where you are using the full dynamic range of the camera and when you are going to do significant additional processing. The goal is to not let the edge sharpening clip to full-white or full-black. Giving yourself a little breathing room with the Blacks and Whites sliders or with the LR/ACR tone curve can also help before adding additional processing.



MikeW
Registered: Dec 06, 2009
Total Posts: 1942
Country: Australia

Yeah I massaged the file today & it came out alright. Processing it in LR itself I can get away with it, but doing it through NIK is where it has issues. NIK must apply sharpening which isn't controllable or it is the "structure" slider that causes it.

I just plan to be more conscious of it & not rush through my editing as I usually do due to time

Thanks,

Mike



Alan321
Registered: Nov 07, 2005
Total Posts: 9933
Country: Australia

I think the image is not as sharp as it ought to be, perhaps because of the half-second exposure time. Because of that Nik will probably try too hard to make it look sharp.

Also, I think that the offending diagonal is a log or plank with a flat top. What looks a bit like a sharpening artefact is just a 3D piece of wood that is better lit on top.

Was the photo taken with a tilt lens ? Not that it matters in terms of your problems with it, but there's a lot of DOF for f/8. I think if you had been able to speed up the shutter speed then it would look much sharper.