How to remove black aberation fringe in a black & white photograph

[Diesel16]

Hello, can anyone advise me how to remove a black fringe on the horizon of a BW landscape image?

I have searched you tube and Google and these forums but the advice given relates to chromatic aberration in colour images. 

I started with a colour image, removed the CA in Light Room and then took the image to Photoshop for editing.

I removed the CA again using the common method (Gaussian blur/ colour blending mode) which worked fine, but as I have used a lot of editing & layers to change the image to BW, the fringing has reappeared as a black line.

I tried the method stated above but that did not work with the BW image.

My work flow used Nik/Google software: Define 2, Viveza and then Silver Efex.

I saw a few comments that the fringing is caused by over sharpening however I have NOT done any sharpening.

Can anyone offer some advice?

[Mohit Goyal]

Hi Diesel,

You may try the below tutorial.

Get Rid of Those Pesky Edge Halos in Photoshop — SitePoint

Thanks,

Mohit

[Diesel16]

Thank you so much for replying – I will check that out

[Trevor.Dennis]

We need to see the image to give a proper answer.  It's very straight forward.  Copy to clipboard and paste to the thread with Ctrl v

[Diesel16]

Thanks for your help...image attached. I hope you can see the fringe on the horizon.

Removing the CA in the colour version seems to have darkened that line.

If this reply doesn't show the image in the thread I will paste separately.

cheers Anne

[Diesel16]

[D Fosse]

Actually this looks like sharpening artifacts to me - there's as much a bright line above the horizon as a dark one below it. I don't think this happened because of CA.

How did you sharpen? There are ways to avoid this kind of thing - primarily using the ACR filter to do sharpening, with a low "detail" setting. You can also sharpen on a duplicate layer and mask out as needed.

[Diesel16]

Thanks for your comment.

I did explain in my original post that I have not done any sharpening whatsoever.

Perhaps it was removing the CA in the colour version that created the bright line?

To be honest I hadn’t noticed it – I was focusing my attention on the black line below the horizon.

[D Fosse]

Diesel16  wrote

I did explain in my original post that I have not done any sharpening whatsoever.

Then it is probably resampled (resized) using "bicubic automatic" or "bicubic sharper", which has sharpening built into the algorithm.

Many people feel that sharpening is too aggressive with these interpolation methods, and I happen to be one of them. I always use "bicubic smoother".

I'm almost 100% certain that this is caused by sharpening, not CA.

[Trevor.Dennis]

Hi Ann  (it's nice to have real names and know who we are talking to)

OK I can't see a dark fringe, but there is a light one pixel halo in places along the horizon.  That is fixable with a semi manual process.

These are zoomed to 200%.  It would be a lot more useful to see a section of your image viewed at 100%  (Ctrl Alt i — Cmd Opt i)

This trick works because skies tend to be lighter than the ground beneather the horizon, and the halos are lighter still.

Add a new layer and set its blend mode to Darken

Use the Clone tool with its blend mode set to Darken, and clone out the halo.

You don't need to mask because the sky won't overwrite the ground which is darker, but the halo being lighter will be overwritten.

This screen shot shows the original (offset) and the fix.  The highlights show the required settings

If I am missing something here (you did say dark fringe) then show us the relevant part of the image at 100%

[Diesel16]

[Diesel16]

You are all amazing at taking the time, I’m very grateful.

Loading up a crop that shows the horizon fringe now

[Diesel16]

Yes – now I’m looking, I can see the light bits. I tried your fix – worked perfectly.

Perhaps I can apply the same principle but use the lighten blending option in place of the darken ones and achieve the opposite? Will give it a try

[Diesel16]

Thanks again Trevor - it all worked perfectly & I have now got rid of the light parts and the dark band too 🙂

It took a while but I am grateful to have learned something new.

I am also impressed that kind people offer solutions and help us less knowledge ones.