Removing Chromatic Aberration using Photoshop |
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smf ![]() Senior Member ![]() Joined: 05 August 2011 Country: Canada Status: Offline Posts: 183 |
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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!
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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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mark.t ![]() Senior Member ![]() Joined: 01 March 2012 Country: United Kingdom Location: Manchester Status: Offline Posts: 237 |
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Love this method of removing Chromatic Aberration. Thank you Frankman.
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geedorama ![]() Groupie ![]() Joined: 12 January 2007 Country: Netherlands Location: Rossum Status: Offline Posts: 143 |
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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/
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tigertimb ![]() Alpha Eyes group ![]() Joined: 22 November 2007 Country: United Kingdom Status: Offline Posts: 5630 |
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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. Edited by tigertimb - 24 June 2011 at 09:15 |
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Tim
If you appreciate comments on your photos, how about returning the favour to others . . . |
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Gabriel ![]() Senior Member ![]() Emeritus Member Joined: 05 December 2006 Location: France Status: Offline Posts: 1931 |
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Go to the Chromatic Aberrations removal tool, move the sliders as you wish, and that's it. |
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Frankman ![]() Emeritus group ![]() Knowledge Base Editor Joined: 02 July 2006 Location: Australia Status: Offline Posts: 6916 |
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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 ***
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wolfy ![]() Senior Member ![]() Joined: 06 June 2008 Country: Australia Location: Wollongong Status: Offline Posts: 1573 |
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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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sybersitizen ![]() Senior Member ![]() Joined: 04 August 2006 Country: United States Location: California Status: Offline Posts: 14457 |
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Actually, 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. Edited by sybersitizen - 26 November 2008 at 04:50 |
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madecov ![]() Senior Member ![]() Joined: 08 April 2008 Country: United Kingdom Location: United States Status: Offline Posts: 730 |
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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
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polyglot ![]() Senior Member ![]() Joined: 25 June 2007 Country: Australia Location: Australia Status: Offline Posts: 3622 |
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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 ![]() 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! Edited by polyglot - 26 November 2008 at 03:43 |
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sybersitizen ![]() Senior Member ![]() Joined: 04 August 2006 Country: United States Location: California Status: Offline Posts: 14457 |
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You don't need to shoot RAW for effective CA correction - you don't even need Photoshop. 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.
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dennismullen ![]() Senior Member ![]() Joined: 15 December 2007 Location: United States Status: Offline Posts: 449 |
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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.
“Those who would sacrifice liberty for safety deserve neither liberty nor safety.” - Ben Franklin. |
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Wētāpunga ![]() Senior Member ![]() Joined: 02 September 2007 Country: New Zealand Location: New Zealand Status: Online Posts: 6829 |
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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
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polyglot ![]() Senior Member ![]() Joined: 25 June 2007 Country: Australia Location: Australia Status: Offline Posts: 3622 |
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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. Chromatic Aberration reference. |
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