Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Redcrown on August 07, 2013, 01:10:38 pm

Title: Halo problem when darkening blue skies
Post by: Redcrown on August 07, 2013, 01:10:38 pm
I often try to darken the blue in landscape skies. I've tried several techniques to darken the blue, but all leave halos around tree leaves, branches, and other hard edges. I know the halos are the result of natural light diffraction around edges. I've tried various techniques to remove the halos after the fact, but can't find anything that works well, other than tedious pixel level cloning. Wondering if anybody has a good method.

Here is a recent example, full frames on top, 200% crops on the bottom to show halos. The images on the left are before darkening the blues. The ones on the right are the result of using the HSL tab in ACR and dragging the blue luminosity slider all the way to the left.

Sometimes I try a B&W adjustment layer in luminosity mode and drag its blue/cyan sliders. Sometimes I try a Selective Color adjustment layer. All give similar results and halos.

(http://kellyphoto.smugmug.com/photos/i-W65JkgN/0/O/i-W65JkgN.jpg)

Anybody wants to play, here is the raw/dng file.

https://dl.dropboxusercontent.com/u/62166185/ANwedding040v0.dng
Title: Re: Halo problem when darkening blue skies
Post by: Peterretep on August 07, 2013, 03:49:08 pm
Diffraction?

Try the clone tool set to darken and sample near where correction is to be made.

Peter
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 07, 2013, 05:54:59 pm
I often try to darken the blue in landscape skies. I've tried several techniques to darken the blue, but all leave halos around tree leaves, branches, and other hard edges. I know the halos are the result of natural light diffraction around edges.

Hi,

What can have a natural cause, is specular reflection of the sun from the leaf surface, depending on orientation to the sun. A polarization filter can prevent some of that.

Quote
I've tried various techniques to remove the halos after the fact, but can't find anything that works well, other than tedious pixel level cloning. Wondering if anybody has a good method.

Well, it's a typical case of prevention being better than a cure. I gave it a quick try (a bit short on time right now), and I'm not too happy with the result, but it is so much better than your result that I still wanted to let you know that there is still hope for images like this. See the attachments for an example of what I get without knowing the optimum Raw conversion settings for your camera and lens.

I used Photoshop ACR (because you also did), although I would normally tackle such files with Capture One or RawTherapee. That may explain some of the things/artifacts I'm not happy about.

I used FocusMagic for Capture sharpening, and Topaz Clarity for halo free darkening of the sky and to add a fair bit of punch to the overall image.

Hope that helps for now.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: Paul2660 on August 07, 2013, 06:09:51 pm
I tried to pull the file down, but only get a bit dump, not sure what I am doing wrong as Bart got it.  I tried the link on both win and mac.

As far the file, for sure a CL-PL will help on the main issue you are having.  You have to be care on this type of shot depending on how wide you are and where the camera lens is in relation to the sun, for you can get a light to dark fade.

I would try pulling down your highlights, slider, in LR 4.x or higher, not sure what version of ACR you are on, but the version of ACR that picked up the LR 4.x highlights slider is CS6 as I recall.  There is a huge difference between CS5 and CS6 in both highlights and shadows sliders.

Pulling down luminance is one way to work the sky to get more blue, however you have to watch that you don't go past the point of no return, which is where you are with the haloing.  I have often felt this mainly because there is a shade of blue, up close to the leaves that is not being effected by the luminance slider. 

Try pulling down the blue luminance in conjunction with the highlights slider if you are CS6 and then consider a ND gradient to the sky.  This will also darken the blue and should not effect the haloing as you are getting. 

Topaz Clarity is a great tool as already mentioned to help some, and the Clarity slider in LR 4.x or LR 5 will also help.  Also you can help this by pulling back a bit on the "whites" slider as it will tone down the area you are having troubles with.

Capture One's color picker works a bit better here in that you can select a blue right up by the leaves and try to darken it. 

If you can get me the file I would love to work it up.

Paul Caldwell
Title: Re: Halo problem when darkening blue skies
Post by: kirkt on August 07, 2013, 11:19:56 pm
If you are trying to accomplish this in LR/ACR with HSL, try using the "aqua" slider instead of blue - slide the luminosity aqua slider to -100.  The effect is more natural, tonally, and there are no artifacts.  Skies are not "blue" sort of cyanish - why HSL has sliders like "aqua" and not "cyan" is puzzling.

Anyway, give it a shot.  The sky darkens, but does not look overly compressed.  The attached 100% crops are with ACR sharpening set to Amount 50, radius 1.0, detail 65, masking 55 (tending toward light deconvolution-like sharpening) to see if aggressive capture sharpening would accentuate artifact from this HSL move.  The small, complete image is from PS, reduced to 1600 px on the long edge, using bicubic - not output sharpening - try with the file and get it into the format you will use and then apply you sharpening to see if the edges at the sky-leaf borders can withstand this technique.

EDIT - you can also use the blue luminance slider to further darken, up to about -25, still with no halo edges; however, at that point the sky is unnatural in tone.

You can also set the combination of tonal controls in raw conversion to get the sky looking the way you want and then apply local modifications to the other elements for which it may be easier to build masks.

kirk
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 08, 2013, 12:47:21 am
I don't have the current version of ACR that comes with PV2012 so I did the HSL/Curve edits in LR4 which uses the same sliders and PV2012 conversion engine.

Here's some screenshots with the settings I used and as a matter of fact skies are not cyan nor are they aqua, they have a magenta element to their hue just not as pronounced. Your sky has too much green in it and the HSL settings I used with the magenta hue shift aided in making the sky look darker along with the curve.
Title: Re: Halo problem when darkening blue skies
Post by: Redcrown on August 08, 2013, 09:30:43 am
Thanks all for the tips. For Paul, the Dropbox link bothers some browsers (Firefox) when you direct click on it. Just right-click and save as.

This sample is just my most recent. Usually I encounter this problem when doing B&W conversions and try to get dramatic black skies against white clouds.

Those dramatic black sky B&W landscapes were one of the primary reasons I got into photography 40 years ago. I saw it, liked it, and wanted it, thus built a home darkroom. It was achieved by using polarizers and heavy red filters on B&W film, and I don't recall ever having a halo problem.

It's interesting that doing a complete sky replacement, while hard work with some advanced masking, is often easier than fixing halos in the existing sky.
Title: Re: Halo problem when darkening blue skies
Post by: Paul2660 on August 08, 2013, 11:01:30 am
Thanks, I forget that every once and a while.

I do better with Capture One Pro vr 7 on shots like this.  As this was a dng, Capture One wasn't able to get the Lens info for some reason, so I had to reimport to LR to work a bit of CA.  

I have attached a crop of my final workup.  I was concerned about blowing out the flowers on the wagon, but still holding the sky.  Capture One IMO has a bit better selective color tool set, but that is just my opinion.  

Thanks for the opportunity.   Be more than happy to send the whole image, just drop me an email.

NOTE, the attached thumbnail does not have the right tone of blue, however when you double click and view it the color is fine. 

Paul Caldwell
Title: Re: Halo problem when darkening blue skies
Post by: David Eichler on August 09, 2013, 12:22:25 pm
Thanks, I forget that every once and a while.

I do better with Capture One Pro vr 7 on shots like this.  As this was a dng, Capture One wasn't able to get the Lens info for some reason, so I had to reimport to LR to work a bit of CA.  

I have attached a crop of my final workup.  I was concerned about blowing out the flowers on the wagon, but still holding the sky.  Capture One IMO has a bit better selective color tool set, but that is just my opinion.  

Thanks for the opportunity.   Be more than happy to send the whole image, just drop me an email.

NOTE, the attached thumbnail does not have the right tone of blue, however when you double click and view it the color is fine. 

Paul Caldwell

Well, that seems to be a significant advantage of C1 over LR/ACR. Does DxO work as well in this regard?
Title: Re: Halo problem when darkening blue skies
Post by: Kirk Gittings on August 10, 2013, 01:00:51 pm
Good thread with lots of good info. Time to spend some time experimenting. This has been a problem for me since I went digital.
Title: Re: Halo problem when darkening blue skies
Post by: Tony Jay on August 10, 2013, 07:01:17 pm
Schewe covers this issue in The Digital Negative.
Blue + yellow = white. He then suggests a technique to solve this in post.

Tony Jay
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 10, 2013, 08:09:49 pm
Schewe covers this issue in The Digital Negative.
Blue + yellow = white. He then suggests a technique to solve this in post.

Hi Tony,

Maybe, but I prefer prevention before cure. With proper (capture) sharpening, based on a good Raw conversion, it is possible to prevent most of the issues.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: David Eichler on August 10, 2013, 11:53:41 pm
Hi Tony,

Maybe, but I prefer prevention before cure. With proper (capture) sharpening, based on a good Raw conversion, it is possible to prevent most of the issues.

Cheers,
Bart

Talking acr/lr? In my experience, no matter how moderate the clarity and sharpening, such haloes will start to appear with a substantial selective darkening via luminosity with the HSL controls.
Title: Re: Halo problem when darkening blue skies
Post by: Kirk Gittings on August 10, 2013, 11:58:32 pm
Talking acr/lr? In my experience, no matter how moderate the clarity and sharpening, such haloes will start to appear with a substantial selective darkening via luminosity with the HSL controls.

Mine too.
Title: Re: Halo problem when darkening blue skies
Post by: ErikKaffehr on August 11, 2013, 02:29:03 am
Hi,

I sometimes use Photoshop create a new layer, multiply and use a luminosity mask. The technique is described here:
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/46-fixing-sky-with-luminosity-mask

The haloing you see is probably mostly an effect sharpening.

Best regards
Erik
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 11, 2013, 07:18:55 am
Talking acr/lr? In my experience, no matter how moderate the clarity and sharpening, such haloes will start to appear with a substantial selective darkening via luminosity with the HSL controls.

Hi David,

Besides the already mentioned specular sky/sun reflections of the edges of leaves, good processing will minimize artifacts.

It starts with proper Raw conversion and Capture sharpening (I prefer better tools like FocusMagic instead of ACR/LR). It does seem like e.g. Capture One  Pro (V7 is significantly improved) or the free RawTherapee (AMAZE demosaicing algorithm) can sometimes extract a bit more resolution out of a given Raw file, which may help. Then it continues with non-halo inducing contrast adjustments, Topaz Clarity is a good example of how it could/should be implemented.

Finally, darkening the blue of a sky by HSL adjustment should not create halos that are not already there. It may enhance the visibility of halos and of the specular reflections on some of the leaf edges, but then those reflections are not halos but rather image detail. Since the darkening by regular HSL usually also creates a color shift (blue -> magenta), I prefer the HSL controls that Topaz Clarity offers, they leave the color intact. Very clever folks at Topaz Labs!

So the whole thing boils down to carefully selecting and then mastering the tools one uses.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: David Eichler on August 11, 2013, 03:23:25 pm
Hi David,

Besides the already mentioned specular sky/sun reflections of the edges of leaves, good processing will minimize artifacts.

It starts with proper Raw conversion and Capture sharpening (I prefer better tools like FocusMagic instead of ACR/LR). It does seem like e.g. Capture One  Pro (V7 is significantly improved) or the free RawTherapee (AMAZE demosaicing algorithm) can sometimes extract a bit more resolution out of a given Raw file, which may help. Then it continues with non-halo inducing contrast adjustments, Topaz Clarity is a good example of how it could/should be implemented.

Finally, darkening the blue of a sky by HSL adjustment should not create halos that are not already there. It may enhance the visibility of halos and of the specular reflections on some of the leaf edges, but then those reflections are not halos but rather image detail. Since the darkening by regular HSL usually also creates a color shift (blue -> magenta), I prefer the HSL controls that Topaz Clarity offers, they leave the color intact. Very clever folks at Topaz Labs!

So the whole thing boils down to carefully selecting and then mastering the tools one uses.

Cheers,
Bart

With the example above, the "halo" effect is clearly not in the original file. With ACR/LR, haloing starts to appear with substantial darkening of the sky, even with little or no clarity or sharpening applied. The example processed with Capture One shows no haloing with substantial darkening of the sky. Seems fairly conclusive to me, although we don't know what clarity and sharpening settings were used for the Capture One example, and whether any compromises had to be made in this regard.

So, I don't really understand your comment about "proper" RAW processing, unless you are saying that you don't feel that ACR/LR permit such RAW processing, relative to other current options. BTW, I still see some haloing in your example with Focus Magic. I see none at all in the Capture One example.


Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 11, 2013, 09:28:35 pm
Hi Bart & Erik,
This problem of halos, when darkening a sky only, is a problem that I also experience. Sometimes, before making a large print where such halos would be noticeable on close inspection, I have in the past enlarged the image about 400% on screen, carefully made selections around the haloed areas, and used the Healing brush to fill in such areas with the adjacent sky.

This process is tedious enough when the halo is along a fairly uncomplicated edge such as the top of a mountain range, but far too tedious when the haloed edges take the form of leaves and branches.

It would be greatly appreciated if Bart or Erik were to use Redcrown's DNg file as an illustration to show us step by step, in ACR and Photoshop because that's what I use for all my processing, how that sky could be darkened to the same degree that Redcrown has done, without the obvious halos.

Erik's example in reply #15 does not show a significantly darkened sky.

Cheers!
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 12, 2013, 08:13:15 am
It would be greatly appreciated if Bart or Erik were to use Redcrown's DNg file as an illustration to show us step by step, in ACR and Photoshop because that's what I use for all my processing, how that sky could be darkened to the same degree that Redcrown has done, without the obvious halos.

Hi Ray,

See the attached examples.

The first attached image is a crop of a straight ACR conversion, no sharpening or Clarity at all. As can be seen, there are no real halos present, but there are a few specular reflection edges where the bright background illumination, bounces of the leaf and branch edges. That nature for you.

The second image took that crop and had it's (HSL Blue) Luminosity reduced to 50% by Topaz Clarity (no other contrast adjustments were activated, only HSL). The Lab chromaticity remained almost the same, which is not possible in Photoshop, hence my recommendation to use a better tool, like Topaz Clarity. I also used an automatic color range mask to select the blue of the sky and leave the blues in the rest of the image alone. The extreme darkening created a few problem areas, but with the great masking tools of Topaz Clarity it was not hard to touch-up a few spots on branches. These problems usually do not occur, but the extreme darkening of a single color range triggered them.

The third image is the second image with some FocusMagic deconvolution sharpening applied. Nothing excessive, because this area was not in the focus-plane to begin with, but rather in the back of the DOF zone (and f/11 reduced a lot of micro-contrast anyway). The specular reflection edges gained some contrast, but at normal viewing magnification that doesn't hurt the image at all. No large halos appeared, because there were none to begin with really.

And finally a screen capture of the three next to each other, zoomed in.

Hope that helps.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 12, 2013, 09:56:49 am
Thanks, Bart.

The first crop of the straight ACR conversion looks the best to me. No halos at all.
It seems you've used Topaz Clarity and Focus Magic to darken the sky, sharpen the leaves which don't seem to benefit from sharpening, and produce halos which are not as obvious as in Redcrown's version, but still noticeable.

What I'd like to see is the first version with no halos at all, but with a darker sky as in the second and third versions. I guess this isn't possible. Right?
Title: Re: Halo problem when darkening blue skies
Post by: 32BT on August 12, 2013, 10:45:22 am
Have you also tried to adjust the whitebalance? For optimal separation of sky and foliage?

As in:
1. set the HSL for blue to excessively dark
2. adjust the whitebalance temp until the halo disappears
3. reset the HSL for blue to something believable.

Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 12, 2013, 11:55:04 am
Thanks, Bart.

The first crop of the straight ACR conversion looks the best to me. No halos at all.
It seems you've used Topaz Clarity and Focus Magic to darken the sky, sharpen the leaves which don't seem to benefit from sharpening, and produce halos which are not as obvious as in Redcrown's version, but still noticeable.

Hi Ray,

There are no halos, just luminance differences between leaf edges  and sky, and branch edges and sky. Topaz Clarity was only used to darken the L in HSL blue. The reflection edges are not the same color blue, therefore they don't darken by that HSL tweak. One could select other bluish tones and darken them, but then one really needs to do some advanced masking to avoid other image colors from being affected.

A simple way to do some crude edge darkening is by using the PS Select|Color range tool and click on the edge detail that you want to darken (it will have a mixed leaf/sky color), adding more to the selection with each click, subtracting if too much is added. Use a smallish range setting like 4 or thereabouts so you can be very selective. Then use that edge selection to create a mask on a duplicate layer, and darken that layer. You can dial in the amount of darkening in real time, so its not to difficult to judge how far to go. See attached example of what that can do in relatively little time. It's not perfect, but using a Polarization filter would have been a better approach if no wide angle lens is used. Prevention is still better than cure.

Quote
What I'd like to see is the first version with no halos at all, but with a darker sky as in the second and third versions. I guess this isn't possible. Right?

Well, not with a simple recipe, but with clever masking one can come a long way. Whether that is really making a better image is another question.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: Redcrown on August 12, 2013, 01:27:13 pm
OP here, and thanks again for all the effort and input. I think we're getting somewhere. Some comments and observations:

Kirkt said move the ACR Aqua slider to -100. I don't get that. When I do that I see no effect on the sky but some strange artifacts around the edges.

Paul2660's sample using C1 Pro is very impressive, but I don't have C1 and don't understand what technique he used after doing a "better selective color".

Some seem to think that the halos are the result of sharpening. I see halos with zero sharpening in ACR or Photoshop.

BartcanderWolf turned me on to Topaz Clarity for HSL adjustments. I have Clarity, but had used it only for the contrast enhancements. Never touched its HSL before. Some interesting potential there.

David Eichler thinks the halo effect is not in the original. I disagree. Blow up a leaf to 1000% and look closely at the edge. There is a definite change in luminosity and color in the 2 to 3 pixels at the edge. Almost always the case in bright sunlit scenes (due to diffraction).

Most interesting to me is the late comment by opgr, suggesting an adjustment of white balance in addition to darkening blue with HSL. I tried that and was amazed how the WB adjustment can actually change the white halos to black.

I did two ACR conversions, one normal, and one with a very bizzare and heavy handed darkening of blues with a WB that made dark halos. I layered the bizzare version on top of the normal one, changed it's blend mode to multiply or darken, then lowered its opacity until I got a sky and leaves I liked. That destroyed the rest of the image, but adding a simple channel mask easily fixed that. I just used a quickly tweaked blue channel from the normal conversion. I encourage others to play with that technique and see what you think.
Title: Re: Halo problem when darkening blue skies
Post by: Kirk Gittings on August 12, 2013, 02:29:09 pm
This halo problem from darkening blue skies for b&w conversion is one of the reasons I stick with film and contrast filters for b&W landscape.
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 12, 2013, 05:58:08 pm
Most interesting to me is the late comment by opgr, suggesting an adjustment of white balance in addition to darkening blue with HSL. I tried that and was amazed how the WB adjustment can actually change the white halos to black.

I did two ACR conversions, one normal, and one with a very bizzare and heavy handed darkening of blues with a WB that made dark halos. I layered the bizzare version on top of the normal one, changed it's blend mode to multiply or darken, then lowered its opacity until I got a sky and leaves I liked. That destroyed the rest of the image, but adding a simple channel mask easily fixed that. I just used a quickly tweaked blue channel from the normal conversion. I encourage others to play with that technique and see what you think.

Hi,

Okay, in the category of extremely out of the box thinking:
1. Do a regular Raw conversion,
2. Create a duplicate layer, with Darker Color Blending mode
3. On that layer, apply a Topaz Black and White Effects filtering with the following settings:
3.1 Reset everything
3.2 Go to 3.Local Adjustments and select the Color adjustment type and the Color brush
3.3 Use a large brush and maximum Opacity and Hardness, with zero Edge Awareness
3.4 Now brush over the entire image, which replaces the B/W conversion with the original color
3.5 Now go to the 1. Conversion panel and only select the color filter
3.6 Select a yellow hue and a high strength which darkens the blue of the sky and brightens the leaves
3.7 Click OK to apply the filter.

Now you can adjust the opacity a bit, or play with the Blend-if layer blending options, and apply a coarse mask to avoid blue land-based colors from being affected.

Cheers,
Bart

P.S. A similar effect can be achieved within Photoshop. Create A duplicate layer in Luminosity Blending mode. Convert it to Black and White where you pull the blues and push the yellows and greens. Now create a composite layer with a Darker color blending mode, and eliminate the B/W conversion layer. Voila!
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 13, 2013, 03:11:40 am
Hi Ray,

There are no halos, just luminance differences between leaf edges  and sky, and branch edges and sky.......

.....Well, not with a simple recipe, but with clever masking one can come a long way. Whether that is really making a better image is another question.

Cheers,
Bart

Hi Bart,

As I recall, the introduction of the Shadows/Highlights tool in Photoshop, some years ago, was a major feature which made darkening highlights, and lightening shadows, much less complicated. One just moves the sliders back and forth till one gets the combination that produces the desired effect.

Likewise, I find that the 'blacks', 'shadows' and 'highlight recovery' sliders in the latest version of ACR 7 seem to produce a greatly improved effect. With this in mind, I thought it should be possible using these basic tools in ACR and Photoshop, to get the desired effect of a significantly darker sky without halos around the leaves.

I think I've achieved this effect using these basic tools. The attached images show the result. They have an embedded sRGB profile. Hope the colors appear as they do on my monitor.

Cheers!
Title: Re: Halo problem when darkening blue skies
Post by: 32BT on August 13, 2013, 06:07:23 am
@Bart
You have exceeded your monthly quotum of the word "Topaz". In fact, when coming from you, combining "Topaz" with "out-of-the-box-thinking" is seriously stretching it.

@Ray
HDR look plus yellow cast??? You've been sucked into the instagram vortex, i take?
Title: Re: Halo problem when darkening blue skies
Post by: 32BT on August 13, 2013, 06:23:26 am
I keep wondering what OP is really trying to achieve. It could be a combination of these:

1. Create a deeper looking sky reminiscent of a clear, sunny day.

2. Add a ND grad effect for toning down the brightness of the sky.

3. Add a vignette effect for emphasizing the cart and flowers.

Depending on the needs, I believe that applying a simple ND grad effect in LR might proof very effective in achieving a desired result. I will also mention once more that a different choice of white balance would help the image in several ways.
Title: Re: Halo problem when darkening blue skies
Post by: Bart_van_der_Wolf on August 13, 2013, 06:40:59 am
@Bart
You have exceeded your monthly quotum of the word "Topaz". In fact, when coming from you, combining "Topaz" with "out-of-the-box-thinking" is seriously stretching it.

Hi Oscar,

In that case, attached the step-by-step Action recipe as I recorded it with only Photoshop functionality, no T***z Labs plugins required. The Merge Visible with Duplicate step is achieved by holding down the ALT (OPTION on a Mac) key when selecting the layer palette menu option. I end the action with an 80% opacity step, but that's on the extreme side for my taste, around 50% would be more digestible. The 80% is chosen to avoid dark halos, and could be seen as the upper side of the opacity range one can use.

With extreme darkening, the sky blue may become a bit noisy, so either a simple Gaussian blur at e.g. 0.4 (we're only blending blue color back in, so we won't lose significant resolution), or a separate noise reduction on the new layer may be in order.

By also darkening the blue reflections on land-based surface areas and shadows, the whole effect looks a bit like using a polarizing filter. Of course, Blue objects in the scene need to be masked to avoid their color changing as well, but that mask can be very crude. Another nice side-effect is that the a*b* channel balance in L*a*b* coordinates is mostly unchanged (no magenta shift), because we only worked with the Luminosity, just as it should be before we decide to e.g. specifically change the blue saturation or vibrance.

Cheers,
Bart
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 13, 2013, 11:24:43 am

@Ray
HDR look plus yellow cast??? You've been sucked into the instagram vortex, i take?

Oscar,
The purpose of the exercise was to create a dark sky without causing halos around the leaves and without causing blocked shadows. Whether or not the overall color balance and contrast is preferred, is another matter.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 13, 2013, 03:56:58 pm
And to be actually honest about this no one is showing their results at the OP's zoom view reference of 300% view where the halos are most pronounced, so no one is comparing apples to apples here.

At that zoom view a print's stochastic dithering is going to conceal that sliver of halo to the point it won't be seen at normal viewing distances including arm's length.

All in all too much time and work put into a problem that won't even be noticed, but at least we all got to see what can be accomplished with different editing approaches and software.
Title: Re: Halo problem when darkening blue skies
Post by: Peterretep on August 13, 2013, 04:46:11 pm
When I first responded to this question I felt that the halos were the result of a a problem with a selection, that the selection was not encompassing the sky areas right adjacent to the leaves and branches, thus those unselected areas of sky remained undarkened and appearing as halos. Is this not the cause?

Peter
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 13, 2013, 05:18:11 pm
When I first responded to this question I felt that the halos were the result of a a problem with a selection, that the selection was not encompassing the sky areas right adjacent to the leaves and branches, thus those unselected areas of sky remained undarkened and appearing as halos. Is this not the cause?

Peter

All you have to do is zoom the edited version that show the halos most pronounced to where you can see individual pixels like maybe 600% view in Photoshop. Sample the RGB readings of the white within the halos to see if there's enough blue. HSL in ACR/LR smoothly tapers off the area of selection in gradual manner. If it was too precise noise would start to kick up along lens induced edge aberrations similar to leaf halos.

Something I hadn't consider might work better and that is to use the saturation/hue sliders in the Camera Calibration panel of ACR/LR. It might offer a more refined gradualness that reaches farther into the white of the halos if they really are completely R=G=B. They might just be greenish white. Hard to tell.
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 13, 2013, 08:45:41 pm
And to be actually honest about this no one is showing their results at the OP's zoom view reference of 300% view where the halos are most pronounced, so no one is comparing apples to apples here.

At that zoom view a print's stochastic dithering is going to conceal that sliver of halo to the point it won't be seen at normal viewing distances including arm's length.

All in all too much time and work put into a problem that won't even be noticed, but at least we all got to see what can be accomplished with different editing approaches and software.

Good point! Here's my 300% crop showing negligible halo effects.

No fancy third-party programs required, and no fancy layering techniques, other than basic ACR adjustments, Shadows/Highlights tool in Photoshop, and a couple of selections with Magic Wand and Quick Selection tool. Oh! And a click on the Auto Contrast button.

What do you think?
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 13, 2013, 09:27:50 pm
If anyone is interested, attached are the basic adjustments I started from. In ACR, three moves to the right and three moves to the left. In Shadows/Highlights, four moves to the right. After that, I selected the flowers to brighten them, and clicked on the Auto Contrast button. I also selected the sky with the Magic Wand, feathered by 2 pixels, and applied a little Gaussian Blur to soften the grain in the sky which was noticeable at 300%. If I were processing the image for sale or for print I would make other adjustments, but as I mentioned, this was just an exercise using PS6, to see how I might overcome this halo problem that I've experienced in the past when trying to do this sort of thing.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 14, 2013, 12:27:08 am
Good point! Here's my 300% crop showing negligible halo effects.

No fancy third-party programs required, and no fancy layering techniques, other than basic ACR adjustments, Shadows/Highlights tool in Photoshop, and a couple of selections with Magic Wand and Quick Selection tool. Oh! And a click on the Auto Contrast button.

What do you think?

I think that's a phenomenal job on that 300% zoomed section of the image, but not so good for the rest of the image which is quite dark and dim for a shot of a cloudless, midday sunlit scene which should look bright.

Is eliminating thin halos on some leaves that aren't an integral part of the image and won't be seen on a print worth making the rest of the image look like that? Sometimes you just have take what you got and move on to better shots.

From my editing around 3000 6MP Raws primarily of similarly lit landscapes I never gave white leaf halos any thought of concern. And the OP is working with much higher resolution images.

First there were Pixel Peepers which I am a member of that club and now with this image...Picky Pixel Pickers™ ;D
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 14, 2013, 09:29:51 am
I think that's a phenomenal job on that 300% zoomed section of the image, but not so good for the rest of the image which is quite dark and dim for a shot of a cloudless, midday sunlit scene which should look bright.

Is eliminating thin halos on some leaves that aren't an integral part of the image and won't be seen on a print worth making the rest of the image look like that? Sometimes you just have take what you got and move on to better shots.

From my editing around 3000 6MP Raws primarily of similarly lit landscapes I never gave white leaf halos any thought of concern. And the OP is working with much higher resolution images.

First there were Pixel Peepers which I am a member of that club and now with this image...Picky Pixel Pickers™ ;D

Tim,
I agree. The image is too dark for a sunny day. But as I mentioned, those adjustments in ACR and Shadows/Highlights were the starting point. I was just trying to see how much of a difference in luminance between the sky and the foliage I could get, using basic techniques that anyone could use, before halos became obvious. I've gone back to the image and lightened it, by special request.  ;D

Is this better?
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 14, 2013, 06:00:00 pm
Tim,
I agree. The image is too dark for a sunny day. But as I mentioned, those adjustments in ACR and Shadows/Highlights were the starting point. I was just trying to see how much of a difference in luminance between the sky and the foliage I could get, using basic techniques that anyone could use, before halos became obvious. I've gone back to the image and lightened it, by special request.  ;D

Is this better?

Much better on the brightness end, Ray, but there's a heavily saturated yellow cast on almost every element that's not sky. The yellow pine wagon seat doesn't look real.

I don't know if that effect is a result of using S/H or maybe our monitor calibration/profiling are not showing what you intend. I'll show a screen shot off my calibrated 27" LG LED next to what new yellow pine should look like on a wagon.
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 14, 2013, 08:44:56 pm
Much better on the brightness end, Ray, but there's a heavily saturated yellow cast on almost every element that's not sky. The yellow pine wagon seat doesn't look real.

Ah! Tim, but that pine wagon seat has been triple-coated with the best quality polyurethane varnish. It's brand new. Compare it with the rest of the wagon which is very dull and weather beaten.

Nevertheless, I agree that the image has a yellow overcast, so I've tweaked the color a bit using  Hue/Saturation and Color Balance sliders. I've also taken the gloss off the seat, to make it more in character with the rest of the wagon.

Better?  ;D
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 14, 2013, 09:13:00 pm
Ah! Tim, but that pine wagon seat has been triple-coated with the best quality polyurethane varnish. It's brand new. Compare it with the rest of the wagon which is very dull and weather beaten.

Nevertheless, I agree that the image has a yellow overcast, so I've tweaked the color a bit using  Hue/Saturation and Color Balance sliders. I've also taken the gloss off the seat, to make it more in character with the rest of the wagon.

Better?  ;D


Oh yeah, much better. I like the way you brought out all the detail in the wagon undercarriage that was completely obscured in shadow.

Hey, I guess we're a PP team.  ;D
Title: Re: Halo problem when darkening blue skies
Post by: Ray on August 15, 2013, 02:55:25 am
Oh yeah, much better. I like the way you brought out all the detail in the wagon undercarriage that was completely obscured in shadow.

Hey, I guess we're a PP team.  ;D

That's the great thing about Photoshop. One can endlessly adjust color and contrast till one is satisfied with the result. But one should bear in mind that not everyone's eyesight is the same. As people get older they tend to become less sensitive to the color blue, so it would not be surprising if an older person were to prefer over-saturated blue skies.  ;)
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 15, 2013, 12:10:28 pm
This halo problem from darkening blue skies for b&w conversion is one of the reasons I stick with film and contrast filters for b&W landscape.

I hear you. Had exactly the same approach for the same reason. Until I tried Silver Efex Pro. Just do not darkien blue in LR/ARC and apply the appropriate filter in SFX. No halos :)

I still have my RZ67, but it is not used anymore.

I still think it is a serious flaw in ACR and I hope they will realize it at some stage and correct it.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 15, 2013, 06:22:19 pm
I hear you. Had exactly the same approach for the same reason. Until I tried Silver Efex Pro. Just do not darkien blue in LR/ARC and apply the appropriate filter in SFX. No halos :)

I still have my RZ67, but it is not used anymore.

I still think it is a serious flaw in ACR and I hope they will realize it at some stage and correct it.

Do you see this halo flaw on all images of leaves surrounded by light blue sky backdrop made darker in ACR/LR? This has not been my experience with my Pentax PEFs, so I'm wondering how this can be considered a flaw with just ACR/LR.

In fact here's a sample of no halo leaf with a darkened blue sky edited in ACR 4.6. The center inset is at 300% view.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 16, 2013, 01:31:37 am
Do you see this halo flaw on all images of leaves surrounded by light blue sky backdrop made darker in ACR/LR?

Maybe not on every picture, but on many. I'd say most of the cases of objects on blue sky background. Branches come to mind.

I say it is a flaw in ACR/LR because every single time I tried a picture with that problem in another RAW converter, it only appeared in ACR/LR.

Now, I do not actually darken blue skies. Doing only B&W, I get the problem when I use yellow, orange and red filtering. But I dont have the problem if I do the filtering in Silver Efex Pro.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 16, 2013, 03:28:08 pm
Quote
I say it is a flaw in ACR/LR because every single time I tried a picture with that problem in another RAW converter, it only appeared in ACR/LR.

Then it is a flaw only with your images AND ACR/LR, not with everyone else.

From what I'm observing and to be more specific in an attempt to deal with all possible variables as to the cause, I would say this most likely has something to do with a combination of lens, angle of light to lens, camera brand/model, sensor type/manufacturer and the information Adobe has access to in order to mitigate this type of aberration within their specific demosaic algorithm and other pre-preview adjustments.

To say it is a flaw caused only by ACR/LR isn't being very accurate or fair to Adobe engineers. I don't experience this halo on my 6MP Pentax DSLR with my kit lens, but I do on a few of my old film legacy lenses that Adobe has no clue about. My digital lens has electronics that communicate with my camera and its relationship with its sensor and the resultant data processed through the A/D converter that delivers the Raw data for Adobe to create default previews.

ACR/LR is doing something right in my case with what little info they have about my camera/lens/sensor combo to work with so I can't agree with you that it's solely a flaw with ACR/LR.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 16, 2013, 03:51:56 pm
Then it is a flaw only with your images AND ACR/LR, not with everyone else.

From what I'm observing and to be more specific in an attempt to deal with all possible variables as to the cause, I would say this most likely has something to do with a combination of lens, angle of light to lens, camera brand/model, sensor type/manufacturer and the information Adobe has access to in order to mitigate this type of aberration within their specific demosaic algorithm and other pre-preview adjustments.


As you wish. Others must be dreaming too.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 16, 2013, 04:04:57 pm
As you wish. Others must be dreaming too.

How many do you count in your consensus of dreamers? Was it accurately derived? This is the first I've heard of these halos being a game changer in preventing a photographer from creating great looking images with ACR/LR and I've been online talking with digital imaging crowd since around 2001.

I'll give you an example of what some of these variables can do to an image when pixel peeping at 300-400% zooms in ACR.

Below is a 400% ACR preview of blue sky backlit tree branches/leaves taken with my Pentax 35-105mm legacy film lens and my Pentax DSLR to show you what a particular lens & sensor brings to demosaicing algorithms. I can't get these types of halo extremes with the same ACR tool adjustments with similar shots taken with my digital kit lens. I don't know why that is but it seems my film lenses can create some very colorful halos using this tool.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 16, 2013, 04:05:54 pm
Tim, you're right.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 16, 2013, 04:14:49 pm
Tim, you're right.

This isn't a battle over who is right, Stephane. It's about having as much as possible all the accurate information available for others to make good decisions on the tools they choose to use.

I don't give a rat's patootie who's right about a point. I just want useful information and so do others. Saying a piece of software is flawed just from judging microscopic halos in a high rez image isn't useful information.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 16, 2013, 04:56:51 pm
Fine, I'll do it.

I took a picture I remembered had the problem in a particularly severe way. The picture was taken with a Canon 5D, not exactly exotic at the time. This with the process version of LR 4.4:

Original picture, default LR 4 rendering:

(http://farm8.staticflickr.com/7361/9526274959_03df1c0925_b.jpg)


Default LR B&W rendering with all cursors to zero:

(http://farm3.staticflickr.com/2826/9526274671_0d61e005e7_b.jpg)


Branches on the right in the previous photo:

(http://farm4.staticflickr.com/3808/9526274503_84bda83d38_b.jpg)


Sky darkened in LR:

(http://farm4.staticflickr.com/3813/9529061640_28dc668aa0_b.jpg)


Branches on the right in previous picture:

(http://farm6.staticflickr.com/5342/9529061784_579dfc47fa_b.jpg)


Pinetree trunk and branches:

(http://farm4.staticflickr.com/3674/9526274753_d9e95efd4b_b.jpg)


Sky darkened with Nik Silver Efex Pro as a smart filter in PS:

(http://farm4.staticflickr.com/3697/9526275015_3e9eba1da9_b.jpg)


Branches in previous photo:

(http://farm8.staticflickr.com/7356/9526274975_4993711a5d_b.jpg)

Pinetree trunk in previous picture:

(http://farm8.staticflickr.com/7355/9526274457_1b5cf5dba9_b.jpg)

So there.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 16, 2013, 05:03:50 pm
Images aren't showing up, Stephane.

You may need to provide crops to keep it at a reasonable size. Notice the sizes of my uploaded screenshots. And they need to be in jpeg format.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 16, 2013, 05:09:09 pm
Images aren't showing up, Stephane.

You may need to provide crops to keep it at a reasonable size. Notice the sizes of my uploaded screenshots. And they need to be in jpeg format.

No, really? Duh. Thanks for your enlightening teachings.
Title: Re: Halo problem when darkening blue skies
Post by: daws on August 16, 2013, 06:40:42 pm
No, really? Duh. Thanks for your enlightening teachings.

Two thoughts Stephane:

1. Your images didn't post.
2. You're sorta acting like a jerk.
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 16, 2013, 09:17:06 pm
Correction. I was wrong on the claim about my film legacy lens as the cause for extreme colored halos when applying Chromatic Aberration adjustments. It does the same on shots with my kit lens only I don't have to use the tool as much.

Also the image of the halo-less orange autumn leaves against a deep blue sky posted above was shot with the same 35-105mm film legacy lens.

So I can't explain the reason why I don't get leaf edge halos in ACR/LR like others are getting.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 17, 2013, 01:33:44 am
You're right on the jerk act. Sorry about that. I edited the links, hopefully it works now.
Title: Re: Halo problem when darkening blue skies
Post by: Oldfox on August 17, 2013, 03:37:45 am
@StephaneB. My virus scanner tells me that there is a virus at your website. Maybe you want to check that.
Title: Re: Halo problem when darkening blue skies
Post by: bernie west on August 17, 2013, 07:18:22 am
Those comparisons are quite startling. 

An interesting experiment to try might be to convert a zeroed out raw in LR to a tiff, and then work on that tiff in LR.  I wonder if the halos would be there or not if you tried darkening the sky on a tiff version.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 17, 2013, 07:40:00 am
An interesting experiment to try might be to convert a zeroed out raw in LR to a tiff, and then work on that tiff in LR.  I wonder if the halos would be there or not if you tried darkening the sky on a tiff version.

Good idea. I just tried, same problem.
Title: Re: Halo problem when darkening blue skies
Post by: Rory on August 17, 2013, 12:27:00 pm
Just for the Record Tim, I have been seeing this halo behavior since Lr 1.0.  It has been discussed in the past.  It takes a fairly extreme adjustment to manifest.  It is particularly problematic using an adjustment brush in auto mask mode.

Rory
Title: Re: Halo problem when darkening blue skies
Post by: Tim Lookingbill on August 17, 2013, 12:40:26 pm
Just for the Record Tim, I have been seeing this halo behavior since Lr 1.0.  It has been discussed in the past.  It takes a fairly extreme adjustment to manifest.  It is particularly problematic using an adjustment brush in auto mask mode.

Rory

Well that makes several people that have this problem, Rory.

Is that useful information in getting it solved? No.

Does your input prove it's wide spread? No.

In an attempt to draw useful information out of you I have to ask you did anyone at Adobe or anyone else offer any causes or solutions in those past discussions?

So far from this discussion it appears the solution as Stephane has demonstrated is to use Nik Silver Efex Pro as a Smart Object or use another Raw converter.
Title: Re: Halo problem when darkening blue skies
Post by: Rory on August 17, 2013, 12:49:30 pm
Well that makes several people that have this problem, Rory.

Is that useful information in getting it solved? No.

Does your input prove it's wide spread? No.

In an attempt to draw useful information out of you I have to ask you did anyone at Adobe or anyone else offer any causes or solutions in those past discussions?

So far from this discussion it appears the solution as Stephane has demonstrated is to use Nik Silver Efex Pro as a Smart Object or use another Raw converter.

I'm just saying it is easy to replicate this behavior, even if not apparently by you.  I am also saying it is a widely known issue even if you were not aware of it.  I do not have the time to search to find the relevant threads, but it is mentioned (at least the auto mask component) in Jeff's digital negative book.  It is not a really big deal and other software, as mentioned, does not create the halos. I find it is more of an issue for creative editing rather than normal photo editing and takes a fairly extreme adjustment to manifest.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 17, 2013, 12:58:12 pm
Just for the Record Tim, I have been seeing this halo behavior since Lr 1.0.  It has been discussed in the past.  It takes a fairly extreme adjustment to manifest.  It is particularly problematic using an adjustment brush in auto mask mode.

Rory

Thanks Rory. I'd only add that I understand it takes extreme adjustments in color, but in B&W mode, just replicating the effect of a red filter on a blue sky will make it appears nearly every time. Before knowing how to avoid it, I stuck to film.
Title: Re: Halo problem when darkening blue skies
Post by: Arlen on August 17, 2013, 08:53:37 pm
I don't know about Capture One, but in LR/ACR getting halos when darkening selections like skies is definitely an issue--especially with the Auto Masked adjustment brush. But that's true for any commonly used edge-bounded method that I've tried, including Photoshop's selection tools such as Magic Wand or Color Range. I've been checking out other techniques to get around those limitations.

The problem is made harder though in the example presented to us by Redcrown because of the nature of the image file. The image is a little too overexposed for easy post processing to a good blue sky. The white flowers are blown out. I would have preferred an exposure about 1 stop less to allow for easier sky recovery. Also, in the original file presented to us, the custom WB has added a yellowish cast, greatly warming the sky and rendering it less blue—making the job of recovering the blue color much more difficult. Those factors force us to make radical adjustments to recover the sky, which accentuate any artifacts.

Lots of you have taken a shot at processing Redcrown's file, and it has been fun and informative to read through. Let me add some remarks about my own attempt, which I think was successful. I stuck with LR4.4 and PS CS6, since that's what most of us use.

I processed first through LR, beginning by resetting Redcrown's dng file adjustments back to default. That included setting the WB to "As Shot", which removes the yellow cast and gives us a good start on that blue sky. Then I optimized various other settings to get the whole image looking as good as possible (to me), without pushing any parameter so far as to cause artifacts. I think the resulting image from LR looks fine, with no halos that will be noticeable in a moderately sized print.

But to get the sky a little darker yet, I took it into CS6 and used a couple of luminosity and gradient masks, together with Levels adjustments, to modestly darken just the brightest tones (sky) in the upper part of the frame. A major advantage of luminosity masks is their ability to automatically feather between contrasting objects in a smooth, natural way. If you don't know about luminosity masks, do a search for them to get to Tony Kuyper's tutorials. He a master of luminosity masking.

Attachments showing the full images are at the bottom of this post, and I would suggest looking at them first.

The following embedded images are 100% crops of the leaves, which to my eye show no artifacts induced by the processing, but as others have noted there are some specular reflections on the edges of some leaves present even in the unadjusted file.

Redcrown's original DNG
(http://www.pbase.com/art1/image/151869830/original.jpg)

LR4.4
(http://www.pbase.com/art1/image/151869832/original.jpg)

LR4.4 + Luminosity Masking in CS6
(http://www.pbase.com/art1/image/151869833/original.jpg)


The first attachment below is a jpeg of the full image generated in LR from Redcrown's "original" dng file, with his settings exactly as I received them. No output sharpening was applied to it or to any of the other attached or embedded images here. Redcrown's file included some capture sharpening, and my versions modified that down to default sharpening settings, which seemed more appropriate to me.

The second attachment is the full image adjusted in LR only, by me.

The third attachment is the full image adjusted in LR plus Luminosity Masking in CS6.

The fourth attachment is a text file describing the steps that were taken in LR and CS6, for anyone interested.

I also have a screen capture of the LR settings that were used, that I can post if requested.

Title: Re: Halo problem when darkening blue skies
Post by: Fine_Art on August 18, 2013, 02:59:26 pm
I often try to darken the blue in landscape skies. I've tried several techniques to darken the blue, but all leave halos around tree leaves, branches, and other hard edges. I know the halos are the result of natural light diffraction around edges. I've tried various techniques to remove the halos after the fact, but can't find anything that works well, other than tedious pixel level cloning. Wondering if anybody has a good method.

Here is a recent example, full frames on top, 200% crops on the bottom to show halos. The images on the left are before darkening the blues. The ones on the right are the result of using the HSL tab in ACR and dragging the blue luminosity slider all the way to the left.

Sometimes I try a B&W adjustment layer in luminosity mode and drag its blue/cyan sliders. Sometimes I try a Selective Color adjustment layer. All give similar results and halos.

(http://kellyphoto.smugmug.com/photos/i-W65JkgN/0/O/i-W65JkgN.jpg)

Anybody wants to play, here is the raw/dng file.

https://dl.dropboxusercontent.com/u/62166185/ANwedding040v0.dng

It seems like most white sky fringing is a byproduct of sharpening methods.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 20, 2013, 03:49:12 pm
Quote from: Fine_Art
It seems like most white sky fringing is a byproduct of sharpening methods.

Actually no. They appear even in the absence of sharpening.
Title: Re: Halo problem when darkening blue skies
Post by: Fine_Art on August 20, 2013, 11:09:47 pm
Actually no. They appear even in the absence of sharpening.

What software are you using?
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 21, 2013, 01:23:51 am
Quote from: Fine_Art
What software are you using?

I suggest your read the thread.
Title: Re: Halo problem when darkening blue skies
Post by: Fine_Art on August 21, 2013, 11:58:18 pm
Ok, I have read the rest that I skipped before (P 2,3). I just dont have this problem with my software. Maybe because any time I am making adjustments that start to trash the image with strange effects I back it off to where I was before. I Do remember having some trouble with some images of very golden leaves in the fall. Maybe try bracketing 1ev the use the sky from the darker shot. Just using the shot in the original post putting the image to -1.2 exposure did not create any problem at 400% view. If you have only 1 shot try -1ev exposure slider then layer that sky with the rest of the shot as normal.
Title: Re: Halo problem when darkening blue skies
Post by: Rory on August 22, 2013, 10:50:41 am
I found this thread (http://feedback.photoshop.com/photoshop_family/topics/adjustment_brush_auto_mask_creates_halos) in Adobe feedback that I started over 2 years ago.  Here are a couple of excerpts of examples I posted to the thread:

Quote
When painting with the adjustment brush with a exposure change along a high contrast boundary a halo is created. Eliminating this behavior, or a "halo cleanup" tool would be very helpful.

Here is an example:

(http://members.shaw.ca/hillrg1/temp/automask.jpg)

Quote
Here is an example, where I painted in a bright color to illustrate the effect on tree branches. I also filled in the area with a color using Nik Color Efex Pro to show that it can be done properly.

(https://d37wxxhohlp07s.cloudfront.net/s3_images/833789/6759d84a-e7fa-4ddb-ad0e-9bae20049941.jpg?1356034651)

So, until Adobe fixes this issue one alternative is to use NIK filters and U-point masking.
Title: Re: Halo problem when darkening blue skies
Post by: Kirk Gittings on August 22, 2013, 03:15:25 pm
Can the NIK program do this on related colors though like green leaves and blue skies?
Title: Re: Halo problem when darkening blue skies
Post by: Rory on August 22, 2013, 08:11:24 pm
Can the NIK program do this on related colors though like green leaves and blue skies?

Yes.

Title: Re: Halo problem when darkening blue skies
Post by: smahn on August 23, 2013, 12:21:06 am
In the Nik shot it appears to be overlaying the branch with color too, IOW not even attempting to find and work within boundaries.
Title: Re: Halo problem when darkening blue skies
Post by: Rory on August 23, 2013, 11:01:45 am
In the Nik shot it appears to be overlaying the branch with color too, IOW not even attempting to find and work within boundaries.

I see that too, but the NIK is still much better.  I think there is room for optimism that Adobe will tweak this in the future.
Title: Re: Halo problem when darkening blue skies
Post by: Arlen on August 23, 2013, 11:07:22 am
With the NIK software, you can put negative control points on the branches, or other areas you want to exclude, and that will usually do a good job of preventing spillover of the effect into those areas.
Title: Re: Halo problem when darkening blue skies
Post by: StephaneB on August 23, 2013, 12:40:46 pm
@StephaneB. My virus scanner tells me that there is a virus at your website. Maybe you want to check that.

Thanks. It is now fixed.