PS: Share Your CA/PF removing techniques

[skaktuss]

I'd like to know, how do You fight against CAs and PFs. Step by step instructions would be much appreciated.
I've read help files about camera raw, but still don't get it. ALT key... remove... sounds so simple, but doesn't work for me. I used to select color and reduce saturation, but in most cases it is very close to sky color and it desaturates beautiful sky tone.

Thanks!

[skaktuss]

Where is everybody? No one has problems with CAs?

[Canada_Rockies]

Originally Posted by skaktuss

Where is everybody? No one has problems with CAs?

I have no CA or PF problems with my DA* 16-50 - after I run it through DxO. Lightroom and Elements 6 are not much help at all. DxO supports the K10D with DA* 16-50, DA* 50-135, DA 18-55 and DA 50-200. Try a test version. It is huge (just under 300 Mb) but does miracles. Price is around USD$100.

[Tom M]

You can usually control CA by stopping down or simply controlling your exposure better.

[falconeye]

Originally Posted by Tom M

You can usually control CA by stopping down or simply controlling your exposure better.

Not if CA is lateral CA.

Tools like DxO can revert the lenses' optical fault giving stunning results (the Hubble way

Other methods (Lightroom etc.) just desaturate typical purple fringe colors and this does not decrease the softness, only reduces irritations by the strong cololrs.


I recommend everybody to learn the effect by applying Photoshop using its "Color/Saturation dialog", Magenta Channel, Brigthness and Saturation both reduced by -50. Some tools use a mask around borders before applying the effect. However, I find that this just destroys the textures.

[skaktuss]

Originally Posted by falconeye

I recommend everybody to learn the effect by applying Photoshop using its "Color/Saturation dialog", Magenta Channel, Brigthness and Saturation both reduced by -50.

I used this method, but as I said, if I reduce blue halo saturation (with hue/saturation menu), sky and other similar tones desaturates too. But I found that before picking a color in hue/saturation menu, better is to make a color selection - Select->color and pick the CA color from picture.
DxO seems to be a good tool, but I don't want to spend 100$ for my little CA problem.

Originally Posted by Tom M

You can usually control CA by stopping down or simply controlling your exposure better.

Stopping down is not a magic solution. Of cource I can stop down, but what if the lighting conditions are not so good?

[shadeless]

there is another method, but its very time-consuming:

using the clone stamp tool with it's mode set to color, just go around the edges of the object that has PF (i guess it works with CA's, too).

it's not the best method, but an alternative if you don't want to affect the whole image.

[roscot]

This can be a lot of work, but you can use the desaturation method as a layer. Apply a mask to the layer and use a black brush to remove the desaturation effect from areas you do not want to effect.

[kaltarrr]

I'm sorry, but what is PF?

[MrApollinax]

Purple Fringing. Typically shows up in high-contrast, bright areas for me.

Purple fringing - Wikipedia, the free encyclopedia

[Peter Zack]

I've actually been very careful and lucky to not see much of this problem but it does creep in. The following shot was taken with the Pentax K mount 300mm f4. High contrast around the bridge and water. This is how the corrected version looks.

So in that shot I used Lightroom 2 to adjust the PF and green fringing that was pretty bad on the bridge and around the water.

So the process was to first use the Aqua slider to reduce the green fringe. That won't effect the green grass. Second was the magenta slider to reduce the purple. Both using the saturation . Next using the Chromatic abberation section, I opened Defringe in "Highlight edges" and adjusted both red/cyan and blue/yellow. That fixed the problem nicely.

This won't work in all shots. Like a sunset that might have a lot of Magenta in the sky. But I've done this many times with other shots to great success.

See the results here tightly cropped:
uncorrected:
Corrected:
If you look at the arches, there's a green outline in the cement and the edges of the concrete against the bright sky have noticeable purple colour shifting that was removed.

[jbinpg]

My old K10D used to purple fringe all the time in contrasty light. I can't seem to get my K20D to do it. I was told the CMOS sensor in the K20 has better gating around each individual pixel to help prevent overflow which is the main cause of PF.

[Bactman]

I have found a way using Photoshop Elements 6 to control purple fringing. The technique is based on this:

Correcting Chromatic Aberrations

Starting with this picture:



Taken with a DA40mm at F4, 1/125s. Note the purple fringing around the leaves in the upper right hand corner:



To address purple fringing using PSE6, I did the following:

1)Under the "Enhance" drop-down tool bar, I selected "Adjust Color"

2)Select "Adjust Hue/Saturation"

OR: To skip this step, hit "Ctrl" + "U"

3)The Hue/Saturation window will pop up. Go to the "Edit" tab, and select "Magenta" from the pull down menu.

4)Move the middle slider for Saturation to -80.

5)Move the last slider for lightness to +16

6)Slowly slide the bottom color slider towards the left while watching the PF. Eventually, the PF will decolorize.

7)Go from there (sharpen, save, whatever).

Here is the final result:



with a crop:

[smcPixellie]

Thanks Bactman thats works for me too.

[fb_penpho]

I use the 'Purple Fringe Remover' control.