Luminous Landscape Forum

Raw & Post Processing, Printing => Adobe Camera Raw Q&A => Topic started by: Chacaboy on June 11, 2012, 03:02:47 am

Title: banding in skies
Post by: Chacaboy on June 11, 2012, 03:02:47 am
I have had some problems with banding in skies from files in ACR. Last night I had serious problems with that in skies from evening shots. Can anyone tell me what causes this and what can be done about it? I have not found a fix including tries with blurring and median filters.
Title: Re: banding in skies
Post by: stamper on June 11, 2012, 03:23:20 am
You don't state what you have done to them. For instance are you pushing the saturation too far? Or extreme curves movements? I used ACR for several years without seeing this problem. Need more information before a solution can be found.
Title: Re: banding in skies
Post by: Tony Jay on June 11, 2012, 04:18:41 am
Given that you are shooting in low-light conditions any tonal adjustments can result in banding if pushed far enough.
It makes postprocessing these sorts of shots a challenge.

Less extreme adjustments are one option.
Perhaps using HDR techniques if you are that way inclined and the type of shot allows it will give you a 32-bit file to tone map

Nonetheless the point Stamper made is valid - until it is known how the file was manipulated no-one will really be able to put their finger on the problem.

Regards

Tony Jay
Title: Re: banding in skies
Post by: Redcrown on June 11, 2012, 11:46:30 am
Banding is a difficult issue. Sometimes it is real, sometimes not. Causes are numerous. So are solutions.

Here is an article that gives one of the best discussion I've seen on banding.

http://trojankitten.posterous.com/suddenly-a-photoshop-tutorial-avoiding-gradie
Title: Re: banding in skies
Post by: JohnBrew on June 11, 2012, 11:47:11 am
Lane, I've had the same problem, but my problem only happened twice - both times with panos stitched in ACR and using different cameras. Were your issues with panos?

BTW, the trojankitten link was posted while I was writing my response. I'm going to give it a try.
Title: Re: banding in skies
Post by: arlon on June 11, 2012, 11:49:33 am
Only have that issue when shooting normal quality jpg. Have you gone to a lower quality jpg anywhere in you procesing flow? Monitor setting maybe or is this on paper?
Title: Re: banding in skies
Post by: kim on June 12, 2012, 07:45:14 am
I think it would help to understand the circumstances and settings when you took the picture. For example, Canon EOS seem to be particularly prone to banding in the sky when used at high ISO. When taking shots at night hand held using 6400 ISO on an 5D II I've seen definite banding in the sky, whereas on the same camera using a tripod and 200 ISO with a long exposure the image is really clean.  You might be able to avoid banding by using a lower ISO.

I've been able to reduce the effect of banding in an image by using a fill layer in Photoshop having the same color as the sky with "Darken" blending mode to fill the lighter areas and setting opacity to 50% or less so that the sky has texture and isn't an obvious fill-in. Obviously this will only work in certain circumstances but it might provide a starting point for you.
Title: Re: banding in skies
Post by: Chacaboy on August 01, 2012, 03:11:07 pm
To All:

I'm SO sorry for the delay in response but I had to rush off to the middle east (Lebanon) where I took the picture in question, and I'm just back to it today. The image was shot at ISO 320 - I use this speed handheld a lot because it's a multiple of the Canon5D native ISO160. It was shot with a Canon 16-35 L series lens at f8. The banding occurs in a bright white area of setting sun in the bkg. that shows up in the histogram as a spike going all the way to the top - so it occurs in the gradient leading up to a blow-out. It was a scout shot I may need to use, but I don't have a low exposure frame to treat it in HDR.

It is best described as a spectral banding because the banding changes colors though its gradient. Opening it up in 16 bit softens the effect slightly but does not eliminate it. I'll try the fill layer in darken mode. Thanks for that as I have been looking for fixes for architectural shots when banding is created in skies during perspective/keystoning correction.  MANY thanks to all. Any other thoughts would be appreciated.

Lane
Title: Re: banding in skies
Post by: Chacaboy on August 01, 2012, 03:26:34 pm
P.S. This was a RAW file, no dng was made. There were no extreme moves. Saturation and vibrance were set at +12. Highlight recovery definitely makes it worse so I took that out. Sharpening was at +70 with 48 points of luminance noise reduction. 0 clarity. Contrast was left at 25.
Title: Re: banding in skies
Post by: Keith Reeder on August 04, 2012, 07:19:27 am
Could you post an example, please? There are different meanings for "banding", and although it sounds like you're talking about posterisation, seeing it would help.
Title: Re: banding in skies
Post by: Chacaboy on August 04, 2012, 05:19:10 pm
Yes, maybe we are talking about posterization. All of my evening architectural work is after sunset - but this time it's different, client driven, and I'm not a sunset kind of photographer so this is new to me with digital. In the end I found a file with less exposure shot from the tripod so I was able to fix most of it. But I won't shoot another sunset image without a lot of hdr brackets. I tried to upload a sample photo but couldn't make it happen. The banding I get in skies in arch shots from perspective adjustments will probably be fixed by the fill in darken mode. Thanks to Kim for that, but it didn't really fix this because of the DMax.

Title: Re: banding in skies
Post by: Wayne Fox on September 15, 2012, 12:08:22 am
The banding occurs in a bright white area of setting sun in the bkg. that shows up in the histogram as a spike going all the way to the top - so it occurs in the gradient leading up to a blow-out.
Possibly what you are seeing is various channels blowing out separately.  What you describe is very common with digital capture ... hard to not get banding around areas that blow out around the sun, since the 3 channels will blow out at different places ... then demoisacing will exacerbate the issue.