Help with CA (maybe)

I have a problem with a raw file. The image contains bare trees against a cloudy sky: in the image corner the sky background has a magenta cast and branches have a magenta color. This does not happen in the image center.

Here is a crop from the center:

Center

And here is a crop from the corner:

Border

The magenta cast in the sky is clearly visible in prints, even if branches are too small to show their color.

The raw file is available from here:

http://www.fsoft.it/temp/P1200584.RW2

It looks like a CA problem, but I have tweaked the CA controls without success.

Does anybody know how to fix this problem?

Thanks in advance.

Fulvio Senore

Try this:

P1200584.RW2.pp3 (12.6 KB)

Here’s another one.P1200584.RW2.pp3 (12.6 KB)

@The_Squirrel_Mafia I downloaded your pp3 file but it is the same as the default one, with just a minor WB correction.

Oh, the Defringe tool! I keep forgetting about it.
Now I remember that you already pointed me to that tool for a previous image: I hope that this time I will remember it.

Your suggestion fixed the problem and I believe that a print should be fine.
Anyway I noticed that the sky behind the branches still has a small magenta cast. It is very small but I still can see it on the screen.
Here is a screenshot with four color pickers in the sky:

As you can see the two pickers at the left show a very similar color, with a small brightness difference.

The two pickers at the right, behind the trees, show a little more red.
I believe that such a sky should have the same color in the whole image, so it looks like that small cast has been introduced by RawTherapee.

Do you have any ideas?

Again, thank you for your help!

2 Likes

Did you also disable the Avoid Color shift in raw ca-correction? If it is enabled in this case (lot of purple fringe) it will introduce a color shift unfortunately :frowning:

That’s a known problem with this option btw.

2 Likes

Disabling “Avoid color shift” fixed the problem: now there is no color cast in the sky.

Again, thank you for your help!

1 Like