C.H.Ling wrote:
> I think CA correction has been discussed before, may be I should have used
> purple fringe instead, I haven't seen any software that can correct them.
>
Winsor posted a good, simple solution a year and a half ago. Here it is
with my commentary from further use/experience:
"Make a hue/saturation adjustment layer.
In the hue/saturation tool use the drop down menu to select blue or magenta.
Click on the color fringe to select its color"
- Once you have chosen a color, you can widen the color selection with the
sliders that appear near the bottom.
"Reduce the saturation with the slider so it is less intense. Then reduce the
lightness with the third slider by an equal amount."
- I do the lightening by eye, not slider setting.
"Keep an eye on the sky so you do not over do it."
- Dr. Mask told me not to worry about this. He says to get the area of concern
right, then use the mask that come with the layer to paint areas in or out of
the anti-fringe effect.
"If the fringe has a wide color range you might have to do it again on the part
that was not changed. This fringe had a strong magenta edge as well."
- This is where the sliders at the bottom make things easier, so you don't need
to do it more than once. With Saturation and Lightness adjusted, you may adjust
the sliders and watch their effect in preview. Makes it easier to set the color
range and feathering range. They may also be readjusted later.
"Helps to look at it at 200 percent while doing it. Easy and quick and will
catch a whole bunch of bare branches against a bright sky. This gets it for me
90 percent of the time without ever having to make a selection."
-----------------------------------------------
> Here are two more samples (last time I posted the Tamron 180/2.5 sample):
>
> - Tamron 70-300 Di LD Macro which Larry just posted some nice flower images,
> the lens is sharp from 70-200 if not for the purple fringe it would be great
> lens:
>
> http://www.accura.com.hk/temp/IMG_2081.JPG (at 180mm F5.6)
>
Here, I applied Winsor's method, reversed the mask to black then painted
in the correction using white. Since the rest of the image is almost
monotone, I took the Saturation slider almost all the way down. That
worked within the 50 minute marker, but left a neutral colored flare
into the black above it. I cloned that out.
<http://www.moosemystic.net/Gallery/tech/Process/PurpleFringe/Watch.htm>
> - The problem is not limited to low cost zoom, the DZ8mm also suffered from
> this problem:
>
> http://www.accura.com.hk/temp/P2112293.jpg (F3.5 1/5s handheld)
>
Here, I applied Winsor's method to the whole image, then painted a
little back in. I removed the effect from the Soloman sign, as it became
too dark. It also looks to me like there are neon strips on the top of
the central and right buildings and the awning to the right of the
Soloman sign. The fringe correction almost eliminated them, so I painted
them back in.
<http://www.moosemystic.net/Gallery/tech/Process/PurpleFringe/BlueLight.htm>
I also applied his technique to the image you posted that, as I recall,
elicited his post.
<http://www.moosemystic.net/Gallery/tech/Process/PurpleFringe/Toyota.htm>
It's not perfect, but amazingly good, relatively simple - and free (at
least for those with PS or equivalent functionality).
Moose
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