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Mostrando los posts 21 - 40 de 35 |
| Technique for dealng with chromatic aberrations (CA) |
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Mensaje posteado el día 07/30/2011, 22:39:21 PM por Androniques |
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Neil270, I4lcocl2, it's unbelievable!.. Thank you so much guys! :) Now I can "restore" so many shots lost for microstock due to this otherwise minor issue with my old Nikon CP-8800, which has always been good in all other terms concerning the picture quality. You made my day... many days :-) |
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Nikon D5000, 18-105mm Nikkor VR, Nikon CP-8800 (rarely,...
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Mensaje posteado el día 07/31/2011, 04:06:40 AM por I4lcocl2 |
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andromantic.............np glad we could be of help. Happy brushing :) |
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Mensaje editado el día 07/31/2011, 05:30:14 AM por Risto40 |
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I've just tried this on one of my butterfly shots (not those i've uploaded here). Amazing! ACR did the most of the job, but there where CR was still visible at some areas, blur method completly fixed it without any other effect for the image (i mean shaprness did not suffer at all).
But with pictures with lot of small details, like forest (leaves, branches), quality suffers significantly (colors will be washed out). |
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Canon.
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Mensaje posteado el día 07/31/2011, 05:52:15 AM por Androniques |
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I4lcocl2, I think one can even automate this procedure for photos taken in similar conditions, so with similar degree of CA/PF... in PS one can record a macro, in GIMP one has to write a script in its special language (script-fu), then apply it to a batch of photos.
Risto40, I guess by varying (reducing for small details) the blur radius one can minimize the dreadful effects while still removing CA/PF efficiently. One can also have a few selections copy-pasted from the original into new layers (with transparent BG) and worked on with different blur radius... |
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Nikon D5000, 18-105mm Nikkor VR, Nikon CP-8800 (rarely,...
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Mensaje posteado el día 07/31/2011, 16:09:45 PM por I4lcocl2 |
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I agree the colours can look washed out if the opacity is set to high, but as long as the lens is of decent quality the CA removal shouldnt be so bad as to be seen at 100%.........at least thats my experience to date
I hadnt thought of using a macro to automate it....prob worth a go see if thats possible |
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Mensaje posteado el día 07/31/2011, 16:20:37 PM por Risto40 |
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I finally selected the CA area (not thightly), made a new layer via copy, used g.blur at 15 and then slightly boosted up and adjusted (if necessary) colors. At the end everything worked out fine. |
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Canon.
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Mensaje editado el día 07/31/2011, 17:13:16 PM por Androniques |
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Risto40,
I have also tried the method on a couple of images from my CP-8800 where the CA are easily seen. The photos were of cityscapes taken in bright sunlight, with nice blue skies and some clouds, so I could examine how the technique deals with areas of smooth gradients if applied uniformly to the entire picture. To my surprise, with the blurred copy overlaid in color blend mode, I saw increased noise levels on the sky and clouds (where there are no traces of CA, of course). Therefore, I decided to try selecting only the sharp and contrasty edges in the picture for blurring and color blending, just as you describe. :)
However, it seems that I went one step further and did not do it manually by hand, but instead used edge detection filter on a greyscale copy in an additional layer. Then I used the color-selection tool for the darkest areas and inverted the selection to get only the edges (well, I also needed to remove some small spots within the cloud areas, easy to deselect with lasso). Finally, I somewhat feathered the selection (4-8 px worked for those photos) and applied blurring only to these relatively small, even tiny selections. For info, I tried two edge-detectors: "2x2 edge detect" and "Gradient", how they are called in GIMP (don't know the names in PS, sorry), and the results were virtually identical.
Update: one may need to also grow the edge-detected selection by 1 or 2 px before proceeding further...
Lastly, while for CA removal one does not need to include the greyscale layer in the final image, there are a number of ways to use it for add-on effects, such as toning or monocle-like soft-glow blending. :) |
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Nikon D5000, 18-105mm Nikkor VR, Nikon CP-8800 (rarely,...
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Archivos cargados:399 | Ventas totales: 391
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Mensaje posteado el día 09/23/2011, 09:00:15 AM por Franant |
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Great tip, thanks! |
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Canon Eos 5D, canon 24-105 L; flash, softbox, brolly...
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Mensaje editado el día 10/03/2011, 07:49:47 AM por M4rio1979 |
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I'm getting very good results getting rid of CA in this blur way, but I have noticed a quite color desaturation on whole image, but this you can manage by add mask to blurred layer and remove blur everywhere but on edges and you have perfect image without CA. |
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SONY Alpha a77 SLT camera with MINOLTA 50mm f1.7, SONY AF DT...
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Mensaje posteado el día 10/03/2011, 15:12:16 PM por Enigmacypher |
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Is the gaussian blur in Gimp similar to the "Normal" setting in Photo Shop? If so, is there a way of specifying a color gaussian blur? |
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Mensaje posteado el día 10/03/2011, 15:17:24 PM por Snille |
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Risto40: What is ACR? |
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Canon 60D
18 MP
18-55mm zoom
Flash: Metz 48 AF - 1 di...
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Mensaje posteado el día 10/03/2011, 21:57:32 PM por Johnnydao |
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ACR = Adobe Camera Raw |
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Canon 5D Mark III, Canon 70-200mm f/2.8L USM II, Canon 16-35...
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Mensaje posteado el día 10/13/2011, 13:58:34 PM por Wimstime |
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I4lcocl2 is correct
You will desaturate the whole image and even add a slight blur with this technique unless you add an inverted mask and only paint on the CA areas :
1 ALT + click the mask icon to add a black mask to the top layer
2 press D for default colors
3 press B use a soft brush with adjusted opacity like I4lcocl2 mentioned above and paint away the CA areas, while zoomed in +200% of course
You might even get away with the sponge tool set to desaturate and paint over the CA areas (be precise though)
Have fun amigos
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Mensaje posteado el día 10/14/2011, 16:41:26 PM por Alanmcdonald |
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Seen a youtube vid on this technique, she uses exactly the same settings, except it changes the complete image slighty so she used a layer to pick out certain parts needing fixed |
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Nikon D90 12.3MP DSLR,
Nikkor 50mm F1.8 D,
Nikkor 18-55mm ...
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Mensaje posteado el día 11/21/2011, 16:48:20 PM por Joyfuldesigns |
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Thanks for the tip, I will have to try this one out. |
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Nikon D5000
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