Halos from post processing (too much, probably :-)

Canon EF 28-135mm f/3.5-5.6 IS USM

12/05/2006 07:29:45 AM · #1

In a lot of my recent challenge entries I have received a number of comments about halos around objects, especially those that blend into the sky, such as trees, fences and other stuff. An example is shown below.

Looking through the threads I can see ways of removing it (colour replacement et al) but I am assuming that I am over processing in some way, with my use of sharpening being the obvious culprit.

Is there anything else it could be as it does not look like chromatic abberation?

mist

Canon EOS-60D

12/05/2006 07:34:48 AM · #2

Erm. Well I'd guess the normal culprit of halos would be excessive use of USM. Try toning it down a bit.

However, in that particular image, is the stuff over to the right not rigging on boats, that has white as part of sails, rather than actual halos ?

Canon EF 24-70mm f/2.8L USM

12/05/2006 07:42:50 AM · #3

Originally posted by mist:

Hmmm - you may be right but it is a halo effect as the original image shows none of the effect. At least it looks as though I am able to diagnose my own faults :-)

Telehubbie

Canon EOS-40D

12/05/2006 08:33:09 AM · #4

Did you burn the sky around those trees? I'm probably wrong here, but it seems that you burned the sky (maybe for shadows) but the thin area around the fuzzy edges of the trees did not get burned due to not being the same level you were burning for and would be further emphasized. And then adding usm emphasizes it even more. The dark parts of the masts appear very dark too, while the white edges of some of those could have been brighter due to reflections or whatever and then when burned becomes more emphasized and then again with usm added. Hope that makes sense, I'm not good at describing things especially at 5am. Everything else looks good, it's just that one little area. Try a before and after crop of that area and post so we could see it better.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

12/05/2006 02:34:01 PM · #5

bump for any other insights or words of wisdom...

Canon EOS-20D

12/05/2006 02:43:31 PM · #6

If might be helpful if you could post what editing steps you're taking - hard to say what you should change otherwise.

Apple iPhone 5

Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED

12/05/2006 02:46:55 PM · #7

Are you selecting areas using masks or the lasso tool? - Sometimes if you select an area and then set feathering or contract the selection the join appears in the wrong place.

Slightly off-topic here... But I missed you getting the D80, congrats! - Are you keeping the FZ20?

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

12/05/2006 02:52:00 PM · #8

If you post the unprocessed original we can better see what you are bringing to the party as far as processing artifacts go.

R.

joshua

Canon EOS-500D Rebel T1i

Canon EF 50mm f/1.8 II

12/05/2006 02:53:25 PM · #9

could it be that you pushed the curve tool too far? it doesn't look like unsharp haloing on the bottom right...it looks like some sort of contrast problem to me

Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED

12/06/2006 04:55:30 PM · #10

Here is the original file - sorry to have taken so long to respond to all of your kind offers of help but work is having one of its moments!

I normally keep very extensive records of what I do in post processing but my notes against this image just says "Lots!". My guess, aside from cropping, is that I ran a contrast mask against the sky by selecting the sky via a polygon lasso selection. I would also have prepared the image a little with levels and curves and the conversion to black and white was done through the channel mixer, with some light noise ninja and probably some usm for sharpness once I had resized it. No wonder it seems such a mess... The original was shot RAW but at the time I only had the primitive Nikon D80 NEF raw tools to hand, so not much done in RAW format.

Anyhow, any help very gratefully received but I think the term "over processed" may be an understatement.

Apple iPhone 5

12/06/2006 05:12:03 PM · #11

Originally posted by obsidian:

by selecting the sky via a polygon lasso selection.

Yea, you have it right there. You can see the effect on the masts on the right. There's some original sky which wasn't included in your selection 'leaking through' and causing the halo effect.

When you're selecting the sky, include these masts as well. They are too thin/contrasty to easily draw around.

Carl Zeiss 50mm ZE f/1.4 Planar T for Canon

12/06/2006 05:16:19 PM · #12

Originally posted by jhonan:

Originally posted by obsidian:
by selecting the sky via a polygon lasso selection.

Yea, you have it right there. You can see the effect on the masts on the right. There's some original sky which wasn't included in your selection 'leaking through' and causing the halo effect.

When you're selecting the sky, include these masts as well. They are too thin/contrasty to easily draw around.

I think I may be about to have one of those Homer Simpson "Doh!" moments... Thanks John.

I have to say, though, that when I apply a contrast mask to the whole of the picture I seem to get a similar effect when I start to play with sharpness, typically using the high pass filter. It looks as though I am starting to over-egg the sharpness at points of high edge contrast with maybe too high a radius set when using sharpening, hence the halo. Strange, too, how it looks worse when you make the image size smaller.

Message edited by author 2006-12-06 17:21:38.

yanko

Canon EOS-5D Mark II

12/06/2006 05:32:59 PM · #13

If you are satisfied with the amount of sharpening everywhere but the area that develops the halos then simply mask away the problem area so that no sharpening is applied there.

Another option is to use the clone tool with a soft brush set at less than 100% opacity. That isn't a good option here but for many cases using a lower opacity clone brush you can make those halos blend into the background completely.

Message edited by author 2006-12-06 17:36:54.

Gaby_G

Canon EOS-5D

Canon EF 28-90mm f/4-5.6 II USM (Black)

12/06/2006 05:38:48 PM · #14

I founded online a cool trick for the usm:

Correct the sharpness in the Lab Color mode, under the luminance channel, aparently that way, reduces halos... I have tried it and it have worked in the pictures I pp`d... Maybe it can help you :D