Fixing chromatic abberation in post processing.

[Pete D.]

I posted this in the Sony Talk forum, but perhaps it is best posted here.

Does anyone have a simple way of reducing the color of CA from f717 photos? Depending on the amount of zoom (or aperature value, I'm not too sure), it varies from red to blue. It is very evident in 11X17 prints, making them pretty much unsaleable. The technique in the "learn" section on this site doesn't seem to work every time and seems to remove or change the specific color you target over the entire selected area, causing some weird results. If I selected only the areas with CA, it would take hours of re-touching. I suppose the ultimate answer is to find a camera that doesn't exhibit these flaws, however, I think it's time to come to grips with what I have and work with it if possible. I've never had to include CA reduction in my workflow, and I would like a technique that is simple and quick.

Cheers! Pete D.

 

[Suzy Q15]

When I want to fix, CA/blooming, I go into Hue/Saturation. Then I choose Magenta usually as the color to work with. After that, I use the middle eyedropper to sample the areas of CA - if the shades are of something other than the color chosen, it whill pick them out. This should give you only the exact values or range of values of the color, not the whole range. Then adjust the different sliders to taste. If this still changes some of the other areas, just Quick Mask them off before making adjustments. I find that sometimes all three adjustments are necessary, Hue, Saturation and Lightness. In regards to the Lightness slider, sometimes you will want to go lighter, sometimes darker If, after I finish there are some stray areas of CA, just clicking on them with the eyedropper will change them to the values already chosen with the sliders. There are other methods, but this usually works most of the time and is easiest.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

 

[Pete D.]

Thanks Susan. This helps. I will try it ASAP. I didn't know that the eyedropper tool was active in this window.
Cheers. Pete D.

When I want to fix, CA/blooming, I go into Hue/Saturation. Then I choose Magenta usually as the color to work with. After that, I use the middle eyedropper to sample the areas of CA - if the shades are of something other than the color chosen, it whill pick them out. This should give you only the exact values or range of values of the color, not the whole range. Then adjust the different sliders to taste. If this still changes some of the other areas, just Quick Mask them off before making adjustments. I find that sometimes all three adjustments are necessary, Hue, Saturation and Lightness. In regards to the Lightness slider, sometimes you will want to go lighter, sometimes darker If, after I finish there are some stray areas of CA, just clicking on them with the eyedropper will change them to the values already chosen with the sliders. There are other methods, but this usually works most of the time and is easiest.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

 

[Joseph S Wisniewski]

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable.

Panorama Tools installs as a PhotoShop plugin (also works with LE and eLEments). Aside from making panoramas, it can correct chromatic aberations, barrel and pincushion distortion, and vignetting.

http://home.no.net/dmaurer/~dersch/Index.htm

And here's a tutorial that, hopefully, isn't too far over the top.

http://www.caldwellphotographic.com/TutorialsDistortionAndColorFringing.html

I'm used to Panorama Tools. Once I've got the correctios set for a particular lens and zoom setting, I can just run an action and batch the corrections.

Ciao!

Joe

 

[Pete D.]

This sounds helpful. Thanks Joseph. I will give it a look. I don't mind spending some time to get it set up as long as I save time later on. It seems that one would have to do tests for each "step" in the cameras zoom in order to be able to use this. That may be very time consuming for a 5X zoom such as the 717.

Cheers! Pete D.

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable.

Panorama Tools installs as a PhotoShop plugin (also works with LE
and eLEments). Aside from making panoramas, it can correct
chromatic aberations, barrel and pincushion distortion, and
vignetting.

http://home.no.net/dmaurer/~dersch/Index.htm

And here's a tutorial that, hopefully, isn't too far over the top.

http://www.caldwellphotographic.com/TutorialsDistortionAndColorFringing.html

I'm used to Panorama Tools. Once I've got the correctios set for a
particular lens and zoom setting, I can just run an action and
batch the corrections.

Ciao!

Joe

 

[Shay Stephens]

It is best to try and avoid the problem in the first place. For future shots try and avoid using wide apertures when shooting scenes that are susceptible to CA. Try using f/4 to f/8, that will greatly reduce the chance of getting CA. Of course it does nothing for the shots already taken ;-)

--
Shay

My Sony F707 & F717 Gallery: http://www.shaystephens.com/portfolio.asp
My F717 Observations: http://www.shaystephens.com/f717.asp

 

[Thomas Niemann]

You'll want to distinguish between CCD blooming and Chromatic Aberration. I've described both at

http://epaperpress.com/pano/index.html

click on Calibration > Color Fringing.

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

--
Thomas Niemann
http://epaperpress.com

 

[fenlander]

Pete,

I'd love to get to grips with the ins and outs of Panorama Tools, but CA is an occasional problem that doesn't seem worth all that effort. I'm doubtful about solutions that rely on reducing saturation in a specific colour: applied globally they distort the whole picture and applied locally they simply remove colour without introducing a viable alternative to the desaturated areas.

Unusually for this forum, I use PaintShop Pro and my working solution is therefore a PSP method. I don't know to what extent this translates to PS.

A couple of examples. I thing this is a typical example of CA:



After treatment:



Trees are a slightly bigger challenge:



But the CA can be removed quite quickly:



Finally, here's an example that combines CA and bloom (I think...). This shot was taken in Antelope Canyon, a dim semi-underground environment with a brillaint sky visible through cracks:



There should be NO blue in this shot. After treatment:



This is how I do it with PSP:

1) Set the Magic Wand to "Match RGB Value" and Tolerance around 20. Use it to select a typical area of purple fringing or bloom.

2) Selections~Modify~Select similar to select all areas of similar colour.

3) Selections~Modify~Expand - 1 pixel.

You should now have all the areas of fringing selected (plus areas that are legitimately the same colour)

4) Use the eyedropper tool to select a "true" colour adjacent to one of the fringed areas

5) Set the Retouch tool to "Colour to target", opacity 100% and a largish brush.

6) Paint across the areas where there is CA or bloom. Avoid areas where the colour is legit.

Afterwards, you may need to deselect and repeat this process a second time to catch any areas of purple that remain - this time you will probably need to select a different colour at step 4.

This whole thing actually only takes a few minutes once you have tried it a couple of times and is well worth doing if the result is to save a good picture.

It would be interesting to know whether there is a PS equivalent to the above.

fenlander

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

 

[Robert Beacon]

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

duplicate layer > sponge tool set to desaturate > small brush> small enough to cover the affected area > start painting

 

[Rylee Isitt]

It seems you can fix CA without any plugins at all, actually. In truth I just downloaded a sample of CA off of the net, and to top it off it was a crop of a much larger image, so this may actually not work at all in the real world. But at least give it a try and let me know how it worked:

Go into your channels area. CA is caused by channels which are actually offset, out of alignment. The image I worked with had a red channel that was quite a bit out of alignment. You can tell if a channel is out of alignment (and therefore causing CA) but quickly changing between viewing R,G,and B channels and the grayscale image in one channel appears to shift.

The CA should not have affected the channels individually - just the alignment of all of the channels in relation to the others.

To fix the image I worked with, all I had to do was nudge the red channel a few pixels to the left and up. Nudge it a bit, then go back to the RGB composite to see how it looks. If it's gotten worse, nudge it in the other direction.

The only problem with this technique is that you'll have to crop a bit of the image out, but only a few pixels.

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

 

[fenlander]

Rylee,

I just tried that with the branches picture from my previous post, but the three channels seem to be in perfect alignment.

fenlander

It seems you can fix CA without any plugins at all, actually. In
truth I just downloaded a sample of CA off of the net, and to top
it off it was a crop of a much larger image, so this may actually
not work at all in the real world. But at least give it a try and
let me know how it worked:

Go into your channels area. CA is caused by channels which are
actually offset, out of alignment. The image I worked with had a
red channel that was quite a bit out of alignment. You can tell if
a channel is out of alignment (and therefore causing CA) but
quickly changing between viewing R,G,and B channels and the
grayscale image in one channel appears to shift.

The CA should not have affected the channels individually - just
the alignment of all of the channels in relation to the others.

To fix the image I worked with, all I had to do was nudge the red
channel a few pixels to the left and up. Nudge it a bit, then go
back to the RGB composite to see how it looks. If it's gotten
worse, nudge it in the other direction.

The only problem with this technique is that you'll have to crop a
bit of the image out, but only a few pixels.

 

[Pete D.]

Thanks to everyone for your helpful comments. As usual you have been very helpful. I think that Thomas may have nailed it when he said that it may be CCD blooming rather than CA. I now have a number of methods to try, and will report which one was best for me.

Thanks to Fenlander for his PSP method. I also use PSP but have access to PS6. If it can be done in PSP then that will probably be my method of choice.
Again, thanks to everyone. I will post my problem and solution photos soon.
Cheers! Pete D.

I just tried that with the branches picture from my previous post,
but the three channels seem to be in perfect alignment.

fenlander

It seems you can fix CA without any plugins at all, actually. In
truth I just downloaded a sample of CA off of the net, and to top
it off it was a crop of a much larger image, so this may actually
not work at all in the real world. But at least give it a try and
let me know how it worked:

Go into your channels area. CA is caused by channels which are
actually offset, out of alignment. The image I worked with had a
red channel that was quite a bit out of alignment. You can tell if
a channel is out of alignment (and therefore causing CA) but
quickly changing between viewing R,G,and B channels and the
grayscale image in one channel appears to shift.

The CA should not have affected the channels individually - just
the alignment of all of the channels in relation to the others.

To fix the image I worked with, all I had to do was nudge the red
channel a few pixels to the left and up. Nudge it a bit, then go
back to the RGB composite to see how it looks. If it's gotten
worse, nudge it in the other direction.

The only problem with this technique is that you'll have to crop a
bit of the image out, but only a few pixels.

 

[Pete D.]

Thanks for this, Fenlander. I gave it a try and it works perfectly! And so fast and precise with no artifacts! Today you're my hero. It took about 2 minutes to fix the photo that I had been having trouble with and I didn't have to learn another program. I actually found that I could get more precise by feathering by 4 instead of expanding. Also using "hue" instead of RGB seemed to work well also. Thanks again! Pete D.

I'd love to get to grips with the ins and outs of Panorama Tools,
but CA is an occasional problem that doesn't seem worth all that
effort. I'm doubtful about solutions that rely on reducing
saturation in a specific colour: applied globally they distort the
whole picture and applied locally they simply remove colour without
introducing a viable alternative to the desaturated areas.

Unusually for this forum, I use PaintShop Pro and my working
solution is therefore a PSP method. I don't know to what extent
this translates to PS.

A couple of examples. I thing this is a typical example of CA:



After treatment:



Trees are a slightly bigger challenge:



But the CA can be removed quite quickly:



Finally, here's an example that combines CA and bloom (I think...).
This shot was taken in Antelope Canyon, a dim semi-underground
environment with a brillaint sky visible through cracks:



There should be NO blue in this shot. After treatment:



This is how I do it with PSP:

1) Set the Magic Wand to "Match RGB Value" and Tolerance around 20.
Use it to select a typical area of purple fringing or bloom.

2) Selections~Modify~Select similar to select all areas of similar
colour.

3) Selections~Modify~Expand - 1 pixel.

You should now have all the areas of fringing selected (plus areas
that are legitimately the same colour)

4) Use the eyedropper tool to select a "true" colour adjacent to
one of the fringed areas

5) Set the Retouch tool to "Colour to target", opacity 100% and a
largish brush.

6) Paint across the areas where there is CA or bloom. Avoid areas
where the colour is legit.

Afterwards, you may need to deselect and repeat this process a
second time to catch any areas of purple that remain - this time
you will probably need to select a different colour at step 4.

This whole thing actually only takes a few minutes once you have
tried it a couple of times and is well worth doing if the result is
to save a good picture.

It would be interesting to know whether there is a PS equivalent to
the above.

fenlander

I posted this in the Sony Talk forum, but perhaps it is best posted
here.

Does anyone have a simple way of reducing the color of CA from f717
photos? Depending on the amount of zoom (or aperature value, I'm
not too sure), it varies from red to blue. It is very evident in
11X17 prints, making them pretty much unsaleable. The technique in
the "learn" section on this site doesn't seem to work every time
and seems to remove or change the specific color you target over
the entire selected area, causing some weird results. If I selected
only the areas with CA, it would take hours of re-touching. I
suppose the ultimate answer is to find a camera that doesn't
exhibit these flaws, however, I think it's time to come to grips
with what I have and work with it if possible. I've never had to
include CA reduction in my workflow, and I would like a technique
that is simple and quick.

Cheers! Pete D.

 

[Joseph S Wisniewski]

You'll want to distinguish between CCD blooming and Chromatic
Aberration. I've described both at

http://epaperpress.com/pano/index.html

click on Calibration > Color Fringing.

Very good point to keep in mind. Blooming isn't anywhere near as easy to correct automatically.

I really enjoyed your site, and am playing with your PTLens right now. Thanks.

Ciao!

Joe

 

[Pete D.]

This is the photo I was having problems with:



This is a crop of the problem area:



And this is a crop of the fixed CA or blooming using Fenlander's technique. Actually I feathered the selection by 4 pixels and used match Hue instead of RGB. I like it! It took about 2 minutes! Thanks Fenlander!

 

[Joseph S Wisniewski]

This sounds helpful. Thanks Joseph. I will give it a look. I don't
mind spending some time to get it set up as long as I save time
later on. It seems that one would have to do tests for each "step"
in the cameras zoom in order to be able to use this. That may be
very time consuming for a 5X zoom such as the 717.

It might be, but I've found I can correct darn near any image, even if I've never seen the particular lens before, in about 3 guesses, taking under 5 minutes.

I think you'll find it much quicker than the "select and paint" methods described in this thread. (Although you should spend some time with those methods too, they are an effective method of correcting CCD blooming. As Thomas Niemann pointed out, that's a very different phenomona).

Another advantages of the Panorama Tools method is that it makes the corners of the image look much better. Not only do you correct the visible CA, but you correct misalignment between the RGB channels that makes the image appear to lack contrast and detail. It really is a technique worth experimenting with.

Ciao!

Joe

 

[Pete D.]

Thanks Joseph. I will take some time and give this a try. How do you tell if the photo is displaying CA or blooming? See my samples in this thread.

Cheers! Pete D.

This sounds helpful. Thanks Joseph. I will give it a look. I don't
mind spending some time to get it set up as long as I save time
later on. It seems that one would have to do tests for each "step"
in the cameras zoom in order to be able to use this. That may be
very time consuming for a 5X zoom such as the 717.

It might be, but I've found I can correct darn near any image, even
if I've never seen the particular lens before, in about 3 guesses,
taking under 5 minutes.

I think you'll find it much quicker than the "select and paint"
methods described in this thread. (Although you should spend some
time with those methods too, they are an effective method of
correcting CCD blooming. As Thomas Niemann pointed out, that's a
very different phenomona).

Another advantages of the Panorama Tools method is that it makes
the corners of the image look much better. Not only do you correct
the visible CA, but you correct misalignment between the RGB
channels that makes the image appear to lack contrast and detail.
It really is a technique worth experimenting with.

Ciao!

Joe

 

[fenlander]

Glad it worked for you. Love the picture!

fenlander

This is the photo I was having problems with:



This is a crop of the problem area:



And this is a crop of the fixed CA or blooming using Fenlander's
technique. Actually I feathered the selection by 4 pixels and used
match Hue instead of RGB. I like it! It took about 2 minutes!
Thanks Fenlander!

 

[Rylee Isitt]

It does look like blooming instead of CA. The examples I've seen of CA all include red and green halos on the fringes of high contrast edges, but this problem seems to be a purple halo that affects less of the surface. Examples of blooming (check this site's glossary) look more like what's happening here.

I just tried that with the branches picture from my previous post,
but the three channels seem to be in perfect alignment.

fenlander

It seems you can fix CA without any plugins at all, actually. In
truth I just downloaded a sample of CA off of the net, and to top
it off it was a crop of a much larger image, so this may actually
not work at all in the real world. But at least give it a try and
let me know how it worked:

Go into your channels area. CA is caused by channels which are
actually offset, out of alignment. The image I worked with had a
red channel that was quite a bit out of alignment. You can tell if
a channel is out of alignment (and therefore causing CA) but
quickly changing between viewing R,G,and B channels and the
grayscale image in one channel appears to shift.

The CA should not have affected the channels individually - just
the alignment of all of the channels in relation to the others.

To fix the image I worked with, all I had to do was nudge the red
channel a few pixels to the left and up. Nudge it a bit, then go
back to the RGB composite to see how it looks. If it's gotten
worse, nudge it in the other direction.

The only problem with this technique is that you'll have to crop a
bit of the image out, but only a few pixels.

 

[Pete D.]

Yep, you're right Rylee. I set up my camera for CA correction using Pano Tools. (BTW this works great, and the 717 exhibits almost no CA from what I can see). Anyway, I applied the correction to this particular photo and of course, the small amount of CA was corrected, but the blooming is still there. This doesn't make me feel any better of course, but now I have a workflow that includes correction which doesn't add an awful lot more work. (a heck of a lot more than with my old S10 though).

Cheers! Pete D.

I just tried that with the branches picture from my previous post,
but the three channels seem to be in perfect alignment.

fenlander

It seems you can fix CA without any plugins at all, actually. In
truth I just downloaded a sample of CA off of the net, and to top
it off it was a crop of a much larger image, so this may actually
not work at all in the real world. But at least give it a try and
let me know how it worked:

Go into your channels area. CA is caused by channels which are
actually offset, out of alignment. The image I worked with had a
red channel that was quite a bit out of alignment. You can tell if
a channel is out of alignment (and therefore causing CA) but
quickly changing between viewing R,G,and B channels and the
grayscale image in one channel appears to shift.

The CA should not have affected the channels individually - just
the alignment of all of the channels in relation to the others.

To fix the image I worked with, all I had to do was nudge the red
channel a few pixels to the left and up. Nudge it a bit, then go
back to the RGB composite to see how it looks. If it's gotten
worse, nudge it in the other direction.

The only problem with this technique is that you'll have to crop a
bit of the image out, but only a few pixels.