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Removing Chromatic Aberration using Photoshop

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Category: Dyxum Community
Forum Name: Knowledge Base
Forum Description: Improving photo techniques & getting more from Dyxum
URL: https://www.dyxum.com/dforum/forum_posts.asp?TID=39068
Printed Date: 18 February 2025 at 09:05


Topic: Removing Chromatic Aberration using Photoshop
Posted By: Frankman
Subject: Removing Chromatic Aberration using Photoshop
Date Posted: 25 November 2008 at 12:00
We all love those old Minolta lenses. The colours are wonderful, however, being designed long before digital, the coatings don’t suppress Chromatic Aberration (CA) very well. We’ve all seen chromatic aberration in our shots. It’s that horrible purple, blue, green or red halo that occurs in regions of high contrast on our images. There are a number of ways of removing CA. I will describe the method I use, which I’ve found to be far superior to most other methods. No matter whether you use old glass or new glass, regardless of how expensive the glass, you will get CA in some shots.

If you look at the following image, you’ll see some horrible purple fringing at the leading edge of the bird’s wing, where black meets white.




In Photoshop, create an adjustment layer: In the layers palette, click on the adjustment layer button at the bottom of the window. Then click on Hue Saturation. Lookie here:



A window will open like this:




From the drop down list where you see “master”, select “Magentas”. Then move the “Saturation” slider down to around -50, and move the “Lightness” slider up to +50 (no need to be exact). Then, if you look down along the bottom of the window, there’s a little slider that you can drag along the “rainbow” until your CA disappears. Magic!

Now, if you’re observant, you will have noticed that there’s a bit of green CA on the back wing – look near the left edge of the image. To remove this artefact, simply repeat the process. Open a new adjustment hue/saturation layer. This time choose greens instead of magentas. Then just repeat the process.



How easy was that! With a bit of practice, you should be able to do this in less than a minute. The result is certainly worth the effort. A lot cheaper than buying new glass too!

Hope you find this technique useful.

Frank


Thanks to Frankman for volunteering this article. It is likely that the technique employed can be adapted for use with other PP programs such as Paint Shop Pro. Feedback to this effect is welcomed.


POSTSCRIPT

A few follow up comments to this article have queried how to overcome the issue of desaturating other parts of the image that you don't want to desaturate.

I delete the hue/saturation layer mast, then add an inverted layer mask (hold down "alt" when you click on the "add layer mask" icon. You'll notice that the layer mask icon is now black, which means "reveal all". Use a white brush (on the layer mask) to go over the areas that are affected by CA. This will restrict the hugh/saturation to these areas only, leaving other areas unaffected.

Hope this makes sense.

Frank


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*** Sony A850 * A700 * Minolta 5D and other stuff ***



Replies:
Posted By: RosieA100
Date Posted: 25 November 2008 at 14:23
I had a go at this earlier today and it really works (as if it wouldn't)!!! Thanks so much Frank for putting this in simple language so I could understand

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a7riii,a77ii
16-35/2.8G, 50/1.7, 90 macro, Lensbaby Composer



Posted By: DavidB
Date Posted: 25 November 2008 at 14:28
Wow! Thank you for this Frankman, I will definitely be using it on some of my work.

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davidbannister.zenfolio.com

a900, a77, RX100 III, 16-50 2.8, 20 2.8, 24 2.8, 28-135, 50 1.7, 100 2.8M, 200 2.8G, 1.4 & 2x TC.


Posted By: momech
Date Posted: 25 November 2008 at 14:53
Thanks Frank. I've tried it a couple of other eays; this looks simpler and very effective.


Posted By: Mark L
Date Posted: 25 November 2008 at 18:39
There is the possibility that the hue/saturation adjustment layers will affect colours elsewhere in the image -- many images contain greens or magentas that you would want to keep.

The solution to this is to create a duplicate of the background layer and move it (left button and drag) above the adjustment layers. Then use the eraser tool to remove the areas where chromatic abberation shows, to reveal the same areas in the adjusted background layer underneath.


Posted By: outback88
Date Posted: 26 November 2008 at 02:27
It would be great if other forum members who use different S/W such as bibble, gimp, rawhide, IDS & others, could also add their CA removal remedies, that way we have everyone covered, l don't use PS but l have a beercan & CA is a problem, l use IDC or Raw Therapee, l don't know how to remove CA in either of these.


Posted By: polyglot
Date Posted: 26 November 2008 at 03:17
Hey guys, just a nitpick, but CA has nothing to do with coatings; it's a lens-design issue wherein the image magnification is wavelength-dependent. Modern lenses like the 16-80ZA have huge CA.

The best way to fix lateral CA is in the RAW processing stage, where you scale the three colour channels independently so that the image magnifications in each channel come out the same. Result is no CA and more sharpness without damaging the colours in other parts of the image or needing to futz around with masking.

Axial CA is more difficult (and still present in modern lenses; the Zeiss 85 and 135 both show it a lot) because it's a matter of different wavelengths focusing behind or in front of the sensor plane, so bright/dark things are uniformly surrounded by a colour depending on which side of the DOF they are. Can't be fixed by scaling the colour channels independently, so Frankman's technique is probably good for axial CA.

http://www.vanwalree.com/optics/chromatic.html - Chromatic Aberration reference.

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C&C always welcome
ex- http://www.brodie-tyrrell.org/pad/ - Pic-A-Day
https://www.flickr.com/photos/24125157@N00/ - on flickr


Posted By: Wētāpunga
Date Posted: 26 November 2008 at 03:19
Originally posted by polyglot polyglot wrote:

...
The best way to fix lateral CA is in the RAW processing stage, where you scale the three colour channels independently so that the image magnifications in each channel come out the same. ...


Hmm, please explain this 'scaling' approach.

Chthonic appreciation- B

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α1, α7cii- Voigtländer 15/4.5, 110/2.5 M; Zeiss Loxia- 21/2.8, 35/2, 50/2 & 85/2.4, Zeiss Batis- 85/1.8 & 135/2.8; Sony 24-105/4 & 100-400/4.5-5.6; Sigma 70/2.8 M; Sony 135/2.8 STF


Posted By: dennismullen
Date Posted: 26 November 2008 at 03:34
I agree the best way to fix CA is to shoot Raw and use the lens corrections tool in ACR. There is a tool in PS too but it messes with the edges of the picture.

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You can see my pictures at http://www.dennismullen.com - http://www.dennismullen.com .

“Those who would sacrifice liberty for safety deserve neither liberty nor safety.” - Ben Franklin.


Posted By: sybersitizen
Date Posted: 26 November 2008 at 03:41
You don't need to shoot RAW for effective CA correction - you don't even need Photoshop. http://epaperpress.com/ptlens - PTLens handles that task and a lot more; it works as a Photoshop plug-in or standalone program; and costs just $25 for a perpetual license.


Posted By: polyglot
Date Posted: 26 November 2008 at 03:41
By scaling, I mean image-scaling. You know, a resize, but applying a different resize factor to each of the R, G and B channels to account for the different magnifications that the lens produces for each colour.

It's not something I've ever attempted manually (and it would be really difficult manually) and ufraw doesn't seem to support it , but there's a "CA correction" option in some RAW converters, at least PS CS and ACR and probably some others too, that will do it for you.

And this is for lateral CA only, but that's the common sort. Axial CA is typically seen only with large apertures, like f/2 or more, and for some reason is a bit less objectionable, at least to me.

edit: thankyou sybersitizen for posting the canonical tool for this!

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C&C always welcome
ex- http://www.brodie-tyrrell.org/pad/ - Pic-A-Day
https://www.flickr.com/photos/24125157@N00/ - on flickr


Posted By: madecov
Date Posted: 26 November 2008 at 04:01
I'm a real novice at RAW, Have not used layers. I don't have a work flow to speak of.
I downloaded a CA "filter" plug and have played with it. It worked well in the one image I played with that was shot with a Minolta 24-85.

This is the original done in IDC


Then I used tweaked it a bit more and used a plug in called PF FREE


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In god we trust........all others are suspects





Posted By: sybersitizen
Date Posted: 26 November 2008 at 04:47
Originally posted by madecov madecov wrote:

... used a plug in called PF FREE

Actually, http://www.sd3.info/pf828/PFree/PFree0-1.html - PFree (if that's the plug-in you mean) is designed to deal with purple fringing, which is a separate phenomenon from frankman's axial CA, which is a separate phenomenon from polyglot's lateral CA!

Purple fringing and axial CA are dealt with by subtracting or desaturating particular colors, but the problem with that is that other matching colors that belong in the scene may also be affected. For example, I can see that the purple flowers in madecov's photo have lost their intensity along with the unwanted purple tinge in the grave marker.

Lateral CA is handled mathematically by rescaling the color channels as polyglot described, so it can usually be fixed without undesirable side effects.


Posted By: wolfy
Date Posted: 26 November 2008 at 05:18
Well I just learnt another photoshop trick I didnt know, if this keeps up I might just learn how to PP properly. Thanks Frank!

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7, 9, 7D, A100, A700, A900. M20/2.8, Arax35/2.8T&S, M50/1.4, CZ85/1.4, Sig105/2.8macro, Ta17-50/2.8, CZ24-70/2.8, CZ135/1.8, M80-200/2.8HSG, M300/2.8APOG, M600/4HSG. 5600HSD, MFC1000+2400+1200.


Posted By: Frankman
Date Posted: 26 November 2008 at 07:07
Thanks for the feedback and alternative suggestions folks. I have added a postscript to the original article which deals with how to overcome the issue of desaturating areas which you don't want to be desaturated.

It's good to see other suggestions coming through as well. I'm learning new stuff too .

Frank

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*** Sony A850 * A700 * Minolta 5D and other stuff ***


Posted By: Gabriel
Date Posted: 26 November 2008 at 08:33
Originally posted by outback88 outback88 wrote:

It would be great if other forum members who use different S/W such as bibble, [...] , could also add their CA removal remedies

Go to the Chromatic Aberrations removal tool, move the sliders as you wish, and that's it.

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Pic a day http://tinyurl.com/2008-p-a-d - 2008 / http://tinyurl.com/2009-pad - 2009 / http://gabriel.mp3-tech.org/pics/galleries/2010_pic_a_day - 2010 galleries


Posted By: tigertimb
Date Posted: 24 June 2011 at 09:11
A rather late addition to this thread, but saw the link from the discussion of purple fringing.

This is almost identical to the way that I would remove fringing, but I would normally lasso the effected area before adding the hue/saturation layer which then fills in the mask for you. You can then always paint in other areas that you also want corrected.

And used to use the same method with paint shop pro too, the only real difference being that they have a colour wheel, but you can still adjust the colour ranges by dragging the marked boundaries on the wheel.

Shoving the saturation up to 100% initially can help whilst adjusting the colour range as it then more clearly shows which bits of the image will be affected.

And I do find that sometimes I will decrease the brightness instead of increasing it, it all depends on the background - with a lattice of purple tree branches being an example.

And it gets a little more tricky when the surrounding details aren't black/white; maybe green bokeh fringing on leaves or skin against a bright sky for instance:
Desaturating the purple then gives people a grey edge which is no better, so from within the same tool/dialgoue, by adjusting the hue slider instead you can essentially make the purples into reds.
It's rarely a perfect solution, and a small adjustment often gives the best results, just toning down the purple, but enough to say that it's less prominent particularly when viewed from a sensible distance.


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Tim
If you appreciate comments on your photos, how about returning the favour to others . . .


Posted By: geedorama
Date Posted: 24 June 2011 at 10:05
I use about the same method as Frankman does, but simply use a duplicate layer in Photoshop, select the bottom layer to make the adjustments, then select the top layer and use a soft eraser- brush to bring out the portions treated for CA while leaving everything else intact.

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http://www.flickr.com/photos/guido_2007/


Posted By: mark.t
Date Posted: 02 March 2012 at 10:42
Love this method of removing Chromatic Aberration. Thank you Frankman.


Posted By: smf
Date Posted: 07 March 2012 at 15:11
Awesome tips! The prevalence of CA has actually made my shy away from bird shots, as I've found it worst on dark birds against a bright sky. With this knowledge in hand, I might go back out and try to find some birds and get some good shots!

Thanks!

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-Scott
*Sony a57, 18-55kit, 18-70kit *Minolta 70-210/4, 50/1.7, 28/2.8, 35-105/3.5-5.6 *KMZ Helios 44-2 *Sigma 90/2.8 Macro *Vivitar 7/3.5 Fisheye *Tair-11a *Tamron 17-50/2.8



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